User:Remig/plico/tug

Tug allows the user to pull or push by mouse actions to move or rotate one part of a polypeptide against the rest by rotation on its psi and phi bonds with collision detection and restriction. It also allows the user to move an entire chain to nest against another chain.

Tug is a member of the Plico suite of protein folding tools described in User:Remig/plico . It may be installed and accessed as a macro with the file:

Title=PLICO Tug
Script=script <path to your scripts folder>/tug.spt;plicotug

saved as plicotug.macro in your .jmol/macros folder as described in Macro.

Copy and paste the following into a text editor and save in your scripts folder as tug.spt.

#   tug - Jmol script by Ron Mignery
#   v1.1 beta    2/12/2014 for Jmol 14
#
#   Translate or rotate a stretch of a polypeptide against itself by mouse actions
#
var kTug = 2
var kDtolerance = 0.2
var kAtolerance = 5.0
var kCtolerance = 1.85
var kMtolerance = 0.8
var gCanchorIdx = -1
var gCanchorNo = -1
var gNanchorIdx = -1
var gNanchorNo = -1
var gCcargoIdx = -1
var gNcargoIdx = -1
var gCcargoNo = -1
var gNcargoNo = -1
var gDestAtomIdx = -1
var g1pivotIdx = -1
var g2pivotIdx = -1
var gSelSaves = ({})
var gCrotors = array()
var gNrotors = array()
var gMouseX = 0
var gMouseY = 0
var gOkCollide = ({})
var gChain = ""
var gMinNo = 1
var gMaxNo = 9999
var gScheme = "Jmol"
var gAltScheme = "Rasmol"
var gCargoSet = ({})
var gMovingSet = ({})
var gBusy = FALSE
var gSCidx = -1
var gSCcircle = -1
var gSCpt = {0 0 0}
var gOK = TRUE # global return value to work around jmol *feature*
var gOk2 = TRUE # "    "
var gTargetPt = {0 0 0}
var gNewDrag = FALSE
var gEcho = ""
var gZoom = ""
var gRotate = ""
var gTow = FALSE
var g1dynamicIdx = -1
var g2dynamicIdx = -1

# Return L tetrahedron point if i1<i2<i3, else R point
function getTet(i1, i2, i3, dist) {
    var v1 = {atomIndex=i3}.xyz - {atomIndex=i2}.xyz
    var v2 = {atomIndex=i1}.xyz - {atomIndex=i2}.xyz
    var axis = cross(v1, v2)
    var pma = ({atomIndex=i1}.xyz + {atomIndex=i3}.xyz)/2
    var pmo = {atomIndex=i2}.xyz + {atomIndex=i2}.xyz - pma
    var pt = pmo + (axis/axis)

    var v = pt - {atomIndex=i2}.xyz
    var cdist = distance(pt, {atomIndex=i2})
    var factor = (dist/cdist)
    var lpt = v * factor

    return lpt + {atomIndex=i2}.xyz
}

function getTrigonal(i1, i2, i3, dist) {
    var v1 = {atomIndex=i1}.xyz - {atomIndex=i2}.xyz
    var v2 = {atomIndex=i3}.xyz - {atomIndex=i2}.xyz
    var pt = {atomIndex=i2}.xyz - (v1 + v2)

    var v = pt - {atomIndex=i2}.xyz
    var cdist = distance(pt, {atomIndex=i2})
    var factor = (dist/cdist)
    var lpt = (v * factor)

    return lpt + {atomIndex=i2}.xyz
}

function abs( x) {
    if (x < 0) {
        x = -x
    }
    return x
}

function getCAmNo (iNo) {
    while ((iNo > 0) and ({(atomno=iNo) and (chain=gChain)}.atomName != "CA")) {
        iNo--
    }
    return iNo
}

function getCAmIdx (idx) {
    var no = {atomIndex=idx and (chain=gChain)}.atomno
    no = getCAmNo( no)
    return ({(atomno=no) and (chain=gChain)}.atomIndex)
}

function getCApNo (iNo) {
    while ((iNo < gMaxNo) and ({(atomno=iNo) and (chain=gChain)}.atomName != "CA")) {
        iNo++
    }
    return iNo
}

function getCpIdx (idx) {
    var no = {atomIndex=idx and (chain=gChain)}.atomno
    no = getCpNo( no)
    return ({(atomno=no) and (chain=gChain)}.atomIndex)
}

function getCpNo (iNo) {
    while ((iNo < gMaxNo) and ({(atomno=iNo) and (chain=gChain)}.atomName != "C")) {
        iNo++
    }
    return iNo
}

function getCApIdx (idx) {
    var no = {atomIndex=idx and (chain=gChain)}.atomno
    no = getCApNo( no)
    return ({(atomno=no) and (chain=gChain)}.atomIndex)
}

function getCmNo (iNo) {
    while ((iNo > 0) and ({(atomno=iNo) and (chain=gChain)}.atomName != "C")) {
        iNo--
    }
    return iNo
}

function getCmIdx (idx) {
    var no = {atomIndex=idx and (chain=gChain)}.atomno
    no = getCmNo( no)
    return ({(atomno=no) and (chain=gChain)}.atomIndex)
}

function getNmNo (iNo) {
    while ((iNo > 0) and ({(atomno=iNo) and (chain=gChain)}.atomName != "N")) {
        iNo--
    }
    return iNo
}

function getNmIdx (idx) {
    var no = {atomIndex=idx and (chain=gChain)}.atomno
    no = getNmNo( no)
    return ({(atomno=no) and (chain=gChain)}.atomIndex)
}

function getNpNo (iNo) {
    while ((iNo < gMaxNo) and ({(atomno=iNo) and (chain=gChain)}.atomName != "N")) {
        iNo++
    }
    return iNo
}

function getNpIdx (idx) {
    var no = {atomIndex=idx}.atomno
    no = getNpNo( no)
    return ({(atomno=no) and (chain=gChain)}.atomIndex)
}

function getCBidx (BBidx) {
    var no = {atomIndex=BBidx}.atomno
    var i = 1
    for (; i < 5; i++) {
        if ({(atomno=@{no+i}) and (chain=gChain)}.atomName == "CB") {
            break
        }
    }
    return {(atomno=@{no+i}) and (chain=gChain)}.atomIndex
}

function getOidx (BBidx) {
    var no = {atomIndex=BBidx}.atomno
    var i = 1
    for (; i < 4; i++) {
        if ({(atomno=@{no+i}) and (chain=gChain)}.atomName == "O") {
            break
        }
    }
    return {(atomno=@{no+i}) and (chain=gChain)}.atomIndex
}

function getNwardBBno (iNo) {
    while ((iNo >= 0) and (
        ({(atomno=iNo) and (chain=gChain)}.atomName != "N")
        and ({(atomno=iNo) and (chain=gChain)}.atomName != "C")
        and ({(atomno=iNo) and (chain=gChain)}.atomName != "CA"))) {
        iNo--
    }
    return iNo
}

function getNwardBBidx (idx) {
    var no = {atomIndex=idx}.atomno - 1
    no = getNwardBBno( no)
    return ((no >= 0) ? ({(atomno=no) and (chain=gChain)}.atomIndex) : -1)
}

function getCwardBBno (iNo) {
    while ((iNo < gMaxNo) and (
        ({(atomno=iNo) and (chain=gChain)}.atomName != "N")
        and ({(atomno=iNo) and (chain=gChain)}.atomName != "C")
        and ({(atomno=iNo) and (chain=gChain)}.atomName != "CA"))) {
        iNo++
    }
    return iNo
}

function getCwardBBidx (idx) {
    var no = {atomIndex=idx}.atomno + 1
    no = getCwardBBno( no)
    return ((no >= 0) ? ({(atomno=no) and (chain=gChain)}.atomIndex) : -1)
}

function getScBBidx (idx) {
    var no = {atomIndex=idx}.atomno
    for (; no > 0; no--) {
        if ({(atomno=no) and (chain=gChain)}.atomName == "CA") {
            break
        }
        else if ({(atomno=no) and (chain=gChain)}.atomName == "C") {
            break
        }
        else if ({(atomno=no) and (chain=gChain)}.atomName == "N") {
            break
        }
        else if ({(atomno=no) and (chain=gChain)}.atomName == "CB") {
            no -= 3
            break
        }
    }
    return {(atomno=no) and (chain=gChain)}.atomIndex
}

function isBBidx(aIdx) {
    var ret = FALSE
    switch({atomIndex=aIdx}.atomName) {
    case "N":
    case "CA":
    case "C":
        ret = TRUE
        break
    }
    return ret
}

function isSCidx(aIdx) {

    var ret = FALSE
    if (isBBidx(aIDx) == FALSE) {

        ret = TRUE
        switch({atomIndex=aIdx}.atomName) {
        case "O":
        case "CB":
            ret = FALSE
            break
        }
    }
    return ret
}

function addSideChainToSelection(CAno, isAdd, addOXT) {
    var iNo = CAno+3
    while ({(atomno=iNo) and (chain=gChain)}.resno == {(atomno=CAno) and (chain=gChain)}.resno) {
        {(atomno=iNo) and (chain=gChain)}.selected = isAdd
        if ({(atomno=iNo) and (chain=gChain)}.atomName == "OXT") {
            {(atomno=iNo) and (chain=gChain)}.selected = addOXT
        }
        iNo++
    }
}

function selectAddSideChain(fromIdx) {
    var iNo = {atomIndex=fromIdx}.atomno
    var iChain = {atomIndex=fromIdx}.chain
    select none
    while ({(atomno=iNo) and (chain=iChain)}.atomName != "N") {
        {(atomno=iNo) and (chain=iChain)}.selected = TRUE
        iNo++
        if (iNo > {chain=iChain}.atomno.max) {
            break
        }
    }
}

# First and last are BB atoms
# Any side atoms in the range are also selected
function selectNwardIdx (firstIdx, lastIdx) {
    var firstno = ((firstIdx < 0) ? {atomIndex=lastIdx}.atomno : {atomIndex=firstIdx}.atomno)
    var lastno = ((lastIdx < 0) ? firstno : {atomIndex=lastIdx}.atomno)
    var iChain = ((firstIdx < 0)
        ? {atomIndex=lastIdx}.chain : {atomIndex=firstIdx}.chain)

    select (atomno <= firstno) and (atomno >= lastno) and (chain = iChain)

    if ({(atomno=firstno) and (chain=gChain)}.atomName == "C") { # if psi
        addSideChainToSelection(firstno-1, TRUE, TRUE)
        {(atomno=@{firstno+1}) and (chain=iChain)}.selected = TRUE # add O
    }
    if ({(atomno=firstno) and (chain=iChain)}.atomName == "CA") {
        addSideChainToSelection(firstno, TRUE, FALSE)
    }
    if ({(atomno=lastno) and (chain=iChain)}.atomName == "C") { # if psi
        addSideChainToSelection(lastno-1, FALSE, FALSE)
    }
}

# First and last are BB atoms
# Any side atoms in the range are also selected
function selectCwardIdx (firstIdx, lastIdx) {
    var firstno = ((firstIdx < 0) ? gMaxNo : {atomIndex=firstIdx}.atomno)
    var lastno = ((lastIdx < 0) ? 1 : {atomIndex=lastIdx}.atomno)
    var iChain = ((firstIdx < 0)
        ? {atomIndex=lastIdx}.chain : {atomIndex=firstIdx}.chain)

    # If nWard anchor in range, begin selection with it
    if ((gNanchorIdx >= 0) and ({atomIndex=gNanchorIdx}.chain == iChain))  {
        var aNo = {atomIndex=gNanchorIdx}.atomno
        if (aNo > firstNo) {
            firstno = aNo
        }
    }

    # If cWard anchor in range, end selection with it
    if ((gCanchorIdx >= 0) and ({atomIndex=gCanchorIdx}.chain == iChain))  {
        var aNo = {atomIndex=gCanchorIdx}.atomno
        if (aNo < lastNo) {
            lastno = aNo
        }
    }

    select (atomno >= firstno) and (atomno <= lastno) and (chain = iChain)

    if ({(atomno=firstno) and (chain=iChain)}.atomName == "C") { # if psi
        addSideChainToSelection(firstno-1, FALSE, FALSE)
    }
    if ({(atomno=lastno) and (chain=iChain)}.atomName == "CA") {
        addSideChainToSelection(lastno, TRUE, FALSE)
    }
    if ({(atomno=lastno) and (chain=iChain)}.atomName == "C") { # if psi
        addSideChainToSelection(lastno-1, TRUE, TRUE)
        {(atomno=@{lastno+1}) and (chain=iChain)}.selected = TRUE # add O
    }
}

# Selected must include second parameter but not the first
function setDistanceIdx (staticIdx, mobileIdx, desired) {
    try {
        var v = {atomIndex=mobileIdx}.xyz - {atomIndex=staticIdx}.xyz
        var dist = distance({atomIndex=staticIdx}, {atomIndex=mobileIdx})
        translateSelected @{((v * (desired/dist)) - v)}
    }
    catch {
    }
}


# Selected must include third parameter but not the first
function setAngleIdx (statorIdx, pivotIdx, rotorIdx, toangle) {
    try {
        var v1={atomIndex=statorIdx}.xyz - {atomIndex=pivotIdx}.xyz
        var v2={atomIndex=rotorIdx}.xyz - {atomIndex=pivotIdx}.xyz
        var axis = cross(v1, v2) + {atomIndex=pivotIdx}.xyz
        var curangle =  angle({atomIndex=statorIdx},
            {atomIndex=pivotIdx}, {atomIndex=rotorIdx})
        rotateselected @axis {atomIndex = pivotIdx} @{curangle-toangle}
    }
    catch {
    }
}

# Selected must include fourth parameter but not the first
function setDihedralIdx (stator1idx, stator2idx, rotor1idx, rotor2idx, toangle) {
    try {
        var a1={atomIndex = stator1idx}.xyz
        var a2={atomIndex = stator2idx}.xyz
        var a3={atomIndex = rotor1idx}.xyz
        var a4={atomIndex = rotor2idx}.xyz
        var curangle =  angle(a1, a2, a3, a4)
        rotateselected {a3} {a2} @{curangle-toangle}
    }
    catch {
    }
}

function countCollisions(rc) {
    var cAtoms = ({})
    for (var idx = {*}.min.atomIndex; idx <= {*}.max.atomIndex; idx++) {
        if ({atomIndex=idx}.size > 0) {
            var lcAtoms = (within(kCtolerance, FALSE, {atomIndex=idx})
                and {atomIndex > idx}
                and not {rc}
                and not connected({atomIndex=idx}))
            if (lcAtoms.size > 0) {
                cAtoms = cAtom or lcAtoms
            }
        }
    }
    return cAtoms.size
}

# Resolve collisions
function handleCollisions2( targetIdx) {

    # For all selected atoms
    for (var iNo = {selected}.min.atomno; iNo <= {selected}.max.atomno; iNo++) {
        var idx = {(atomno=iNo) and (chain=gchain)}.atomIndex
        if ({atomindex=idx}.selected) {

            # Collect local colliders
            var lcAtoms = (within(kCtolerance, FALSE, {atomIndex=idx})
                and not {atomIndex=idx}
                and not {gOkCollide}
                and not connected({atomIndex=idx}))
            if (lcAtoms.size > 0) {

                # Ignore kinked BB
                if (isBBidx(idx) and angle({atomIndex=@{getCwardBBidx(idx)}},
                    {atomIndex=idx} , {atomIndex=@{getNwardBBidx(idx)}}) < 100) {
                    continue
                }

                # For all local colliders
                for (var c = 1; c <= lcAtoms.size; c++ ) {
                    var cidx = lcAtoms[c].atomIndex

                    # If it is with water, delete it
                    if (lcAtoms[c].group = "HOH") {
                        delete {atomIndex=cidx}
                    }

                    # else if it is with side chain not proline, fix it
                    else if (isSCidx(cidx) and ({atomIndex=cidx}.group != "PRO")) {
                        fixSCcollision2(cidx)
                        recollect = TRUE

                        # If not fixed, exit fail
                        if (gOk2 == FALSE) {
                            return # early exit (break n jmol bug)
                        }
                    }

                    # else if it is itself a side chain not proline, fix it
                    else if (isSCidx(idx) and ({atomIndex=idx}.group != "PRO")) {
                        fixSCcollision2(idx)
                        recollect = TRUE

                        # If not fixed, exit fail
                        if (gOk2 == FALSE) {
                            return # early exit (break n jmol bug)
                        }
                    }

                    # Else if it is with O, counter-rotate
                    else if (lcAtoms[c].atomName = "O") {
                        counterRotate2(lcAtoms[c].atomIndex,
                            {atomIndex=idx}.xyz, targetIdx, FALSE)

                        # If not fixed, exit fail
                        if (gOk2 == FALSE) {
                            return # early exit (break n jmol bug)
                        }
                    }

                    # Else if it is itself O, counter-rotate
                    else if ({atomIndex=idx}.atomName = "O") {
                        counterRotate2(idx, lcAtoms[c].xyz, targetIdx, FALSE)

                        # If not fixed, exit fail
                        if (gOk2 == FALSE) {
                            return # early exit (break n jmol bug)
                        }
                    }

                    else {    # Else not fixed, exit fail
                        gOk2 = FALSE
                        return # early exit (break n jmol bug)
                    }
                } # endfor
            }
        }
    } # endfor iNo
}

# Rotate rotor set to move target atom to its proper place
function tugTrackIdx(targetIdx, targetPt, nWard, cDetect) {
    gOK = FALSE
    var pt = targetPt
    var dist = distance(pt, {atomIndex=targetIdx}.xyz)

    var rotors = (nWard ? gNrotors : gCrotors)

    # For a number of passes
    for (var pass1 = 0; pass1 < 20; pass1++) {
        var blocked = ({})
        for (var pass2 = 0; pass2 < (rotors.size/4); pass2++) {

            var v1 = {atomIndex=targetIdx}.xyz - pt

            # Find the most orthgonal unused rotor
            var imax = 0
            var smax = 0.5
            for (var i = 1; i < rotors.size; i += 4) {
                var i2 = rotors[i+1]
                var i3 = rotors[i+2]
                var i4 = rotors[i+3]
                if ((i2 != targetIdx) and (i3 != targetIdx) and (i4 != targetIdx)) {
                    if ({blocked and {atomIndex=i2}}.count == 0) {
                        var v2 = {atomIndex=i3}.xyz - {atomIndex=i2}.xyz

                        var s = sin(abs(angle(v1, {0 0 0}, v2)))
                        if (s > smax) {
                            smax = s
                            imax = i
                        }
                    }
                }
            }

            # If no more rotors, break to next full try
            if (imax == 0) {
               break
            }
            var i1 = rotors[imax+0]
            var i2 = rotors[imax+1]
            var i3 = rotors[imax+2]
            var i4 = rotors[imax+3]

            # Get dihedral of rotor with target point
            var dt = angle({atomIndex=targetIdx}, {atomIndex=i2}, {atomIndex=i3}, pt)
            var dh = angle({atomIndex=i1}, {atomIndex=i2}, {atomIndex=i3}, {atomIndex=i4})
            if (dh == "NaN") {
                dh = -50
            }
            var psi = dh + dt
            var phi = dh + dt

            # Compute resultant psi and phi
            #  and select from target atom to first half of rotor
            var movePt = FALSE
            if (nWard) {
                if ({atomIndex=i2}.atomName="CA") {
                    psi = angle({atomIndex=@{getCwardBBidx(i1)}}, {atomIndex=i1},
                        {atomIndex=i2}, {atomIndex=i3}) + dt
                }
                else {
                    phi = angle({atomIndex=i1}, {atomIndex=i2},
                        {atomIndex=i3}, {atomIndex=@{getNwardBBidx(i3)}}) + dt
                }

                if ({atomIndex=i2}.atomno > {atomIndex=targetIdx}.atomno) {
                    movePt = TRUE
                    selectNwardIdx(i3, getCwardBBidx(targetIdx))
                    {atomIndex=targetIdx}.selected = TRUE
                }
                else {
                    selectCwardIdx(i2, targetIdx)
                }
            }
            else {
                if (({atomIndex=i2}.atomName="CA")) {
                    phi = angle({atomIndex=@{getNwardBBidx(i1)}}, {atomIndex=i1},
                        {atomIndex=i2}, {atomIndex=i3}) + dt
                }
                else {
                    psi = angle({atomIndex=i2}, {atomIndex=i3},
                        {atomIndex=i4}, {atomIndex=@{getCwardBBidx(i4)}}) + dt
                }

                if ({atomIndex=i2}.atomno < {atomIndex=targetIdx}.atomno) {
                    movePt = TRUE
                    selectCwardIdx(i3, getNwardBBidx(targetIdx))
                    {atomIndex=targetIdx}.selected = TRUE
                }
                else {
                    selectNwardIdx(i2, targetIdx)
                }
            }

            # Relax rules if desperate
            if (pass1 > 10) {
                phi = -50
            }

            # If rotation within ramachandran limits
            if ((abs(dt) >= 0.1) and
                (({atomIndex=i2}.group=="GLY") or (phi < 0))) {

                # If moving target point, put the target atom there
                var cp = {atomIndex=targetIdx}.xyz
                if (movePt) {
                    dt = -dt
                    {atomIndex=targetIdx}.xyz = pt
                }

                # Rotate to minimize vector ====================
                rotateSelected {atomIndex=i2} {atomIndex=i3} @dt

                # If collision checking
                if (cDetect) {

                    # If collision, back off by eighths
                    var wasCollision = FALSE
                    for (var ci = 0; ci < 4; ci++) {
                        if (ci < 3) {
                            dt /= 2
                        }
                        handleCollisions2( nWard, targetIdx)
                        if (gOk2==FALSE) {
                            wasCollision = TRUE
                            rotateSelected {atomIndex=i2} {atomIndex=i3} @{-dt}
                        }
                        else if (wasCollision) {
                            if (ci <3) {
                                rotateSelected {atomIndex=i2} {atomIndex=i3} @{dt}
                            }
                        }
                        else {
                            break
                        }

                        if (dt < 0.01) {
                            break
                        }
                    } # endfor
                }

                # If moving target point, put the target atom back
                if (movePt) {
                    pt = {atomIndex=targetIdx}.xyz
                    {atomIndex=targetIdx}.xyz = cp
                }

            }

            # If close enough, stop
            if (distance(pt, {atomIndex=targetIdx}) < kDtolerance) {
                gOK = TRUE
                gTargetPt = pt
                break
            }

            # Block rotor
            blocked |= {atomIndex=i2}

        }   # endfor num rotors passes

        if (gOK) {
            break
        }
    }   # endfor 10 passes
}

# Counter rotate bonds on either side of a BB O
function docounterRotate(caPhiIdx, nIdx, cIdx, oIdx, caPsiIdx, dir, nWard) {

    # Rotate psi
    {atomIndex=nIdx}.selected = nWard
    {atomIndex=cIdx}.selected = nWard
    {atomIndex=oIdx}.selected = nward
    rotateSelected {atomIndex=caPsiIdx} {atomIndex=cIdx} @{dir}

    # Counter-rotate phi
    {atomIndex=nIdx}.selected = not nWard
    {atomIndex=cIdx}.selected = not nWard
    {atomIndex=oIdx}.selected = not nward
    rotateSelected {atomIndex=nIdx} {atomIndex=caPhiIdx} @{-dir}
}

function counterRotate(oIdx, dir, nWard) {

    var selsave = {selected}
    var iChain = {atomIndex=oIdx}.chain
    var cIdx = getScBBidx(oIdx)
    var nIdx = getCwardBBidx(cIdx)
    var caPhiIdx = getCwardBBidx(nIdx)
    var caPsiIdx = getNwardBBidx(cIdx)

    if (nWard) {
        nNo = {chain=iChain}.atomno.min
        selectNwardIdx(caPsiIdx, {(atomno=nNo) and (chain=iChain)}.atomIndex)
    }
    else {
        cNo = {chain=iChain}.atomno.max
        selectCwardIdx(caPhiIdx, {(atomno=cNo) and (chain=iChain)}.atomIndex)
    }

    # Counter-rotate
    docounterRotate(caPhiIdx, nIdx, cIdx, oIdx, caPsiIdx, dir, not nWard)
    select selsave
}

function counterRotate2(oIdx, toPt, terminalIdx, oDrag) {

    var selsave = {selected}
    var gOk2 = TRUE
    var cIdx = getScBBidx(oIdx)
    var nIdx = getCwardBBidx(cIdx)
    var caPhiIdx = getCwardBBidx(nIdx)
    var caPsiIdx = getNwardBBidx(cIdx)

    var nTward = ({atomIndex=oIdx}.atomno < {atomIndex=terminalIdx}.atomno)
    if (nTward) {
        selectCwardIdx(cIdx, terminalIdx)
    }
    else {
        selectNwardIdx(nIdx, terminalIdx)
    }

    # Until all collisions cancelled
    var dir = 5
    var ang = angle(toPt, {atomIndex=oIdx}, {atomIndex=cIdx})
    var tcount = 0
    while (oDrag or (within(kCtolerance, FALSE, {atomIndex=oIdx})
            and not {atomIndex=oIdx} and not connected({atomIndex=oIdx})
            and not {gOkCollide} > 0)) {

        # Counter-rotate
        docounterRotate(caPhiIdx, nIdx, cIdx, oIdx, caPsiIdx, dir, nTward)
        var newang = angle(toPt, {atomIndex=oIdx}, {atomIndex=cIdx})

        # If wrong direction once, undo and reverse
        if (newang > ang) {
            docounterRotate(caPhiIDx, nIdx, cIdx, oIdx, caPsiIdx, -dir, nTward)

            # If first time, continue in opposite direction
            dir *= -1
            if (dir < 0) {
                continue
            }
        }

        if (oDrag) {
            break
        }

        # If no go, undo and exit
        tcount++
        if (tcount > (360/abs(dir))) {
            gOk2 = FALSE
            break
        }

    } # endwhile
    select selsave
}

# Repair proline
function repairProline(BBidx) {
    var cbidx = getCBidx(BBidx)
    var cbno = {atomIndex=cbidx}.atomno
    var cgidx = {(atomno=@{cbno+1}) and (chain=gChain)}.atomIndex
    var cdidx = {(atomno=@{cbno+2}) and (chain=gChain)}.atomIndex
    var caidx = {(atomno=@{cbno-3}) and (chain=gChain)}.atomIndex
    var nidx = {(atomno=@{cbno-4}) and (chain=gChain)}.atomIndex

    select {atomIndex=cbidx}
    setAngleIdx(nidx, caidx, cbidx, 109.5)

    select {atomIndex=cdidx}
    setDistanceIdx(nidx, cdidx, 1.47)
    setAngleIdx(caidx, nidx, cdidx, 102.7)
    setDihedralIdx(cbidx, caidx, nidx, cdidx, 16.2)

    select {atomIndex=cgidx}
    setDistanceIdx(cdidx, cgidx, 1.51)
    setAngleIdx(nidx, cdidx, cgidx, 106.4)
    setDihedralIdx(caidx, nidx, cdidx, cgidx, 16.2)
}

# Repair side chain
function repairSideChain(targetIdx, nWard) {

    var idx = (nWard ? getCwardBBidx(targetIdx) : getNwardBBidx(targetIdx))

    if (({atomIndex=targetIdx}.atomName == "CA")
        and ({atomIndex=targetIdx}.group != "GLY")) {
        var cbidx = getCBidx(targetIdx)
        select none
        selectAddSideChain(cbidx)
        setAngleIdx(idx, targetIdx, cbidx, 110.0)
        setDistanceIdx(targetIdx, cbidx, 1.5)
        if ({atomIndex=targetIdx}.group != "PRO") {
            var colliders = (within(kCtolerance, FALSE, {selected})
                and not {atomIndex=targetIdx} and not {selected})
            if (colliders.size > 0) {
                if ({atomIndex=targetIdx}.group != "ALA") {
                    fixSCcollision2(cbidx)
                }
            }
        }
        else {
            if (nWard) {
            }
            else {
                setDihedralIdx(getNwardBBidx(idx), idx, targetIdx, cbidx, 174.2)
            }
        }
    }

    else if ({atomIndex=targetIdx}.atomName == "C") {
        var oidx = getOidx(targetIdx)
        select {atomIndex=oidx}
        setAngleIdx(idx, targetIdx, oidx, 120.0)
        setDistanceIdx(targetIdx, oidx, 1.21)
        if (nWard) {
            setDihedralIdx(getCwardBBidx(idx), idx, targetIdx, oidx, 0.0)
        }
        if ({atomIndex=idx}.group == "PRO") {
            repairProline(idx)
            var dNo = {atomIndex=targetIdx}.atomno + 4
            var dIdx = {(atomno=dNO) and (chain=gChain)}.atomIndex
            var colliders = (within(kCtolerance, FALSE, {atomIndex=dIdx})
                and not connected({atomIndex=dIdx})
                and not {atomIndex=dIdx})
            for (var i = 1; i <= colliders.size; i++) {
                if (colliders[i].atomName == "O") {
                    counterRotate2(colliders[i].atomIndex,
                        {atomIndex=dIdx}.xyz, targetIdx, FALSE)
                }
            }
        }
    }
}

# Rebuild Cward rotors set
function tugTrackC() {

    # For all bb atoms cWard of cargo
    var targetIdx = gCcargoIdx
    var okCount = 0

    # Allow collisions with cargo
    gOkCollide = gCargoSet
    var tcount = 0
    while (targetIdx != gCanchorIdx) {

        # Step to next atom
        targetIdx = getCwardBBidx(targetIdx)

        # No collision with cargo allowed after two atoms placed
        if (tcount == 2) {
           gOkCollide = ({})
        }
        tcount++

        # Compute targets desired coords
        var c1idx = getCwardBBidx(targetIdx)
        var n1idx = getNwardBBidx(targetIdx)
        var n2idx = getNwardBBidx(n1Idx)
        var n3idx = getNwardBBidx(n2Idx)
        var pt = {0 0 0}
        if ({atomIndex=targetIdx}.atomName == "N") {
            var oidx = getOidx(n1idx)
            select {atomIndex=oidx}

            # Desired target location is trigonal O
            setDistanceIdx(n1idx, oidx, 1.5)
            pt = getTrigonal(n2idx, n1idx, oidx, 1.37)
            setDistanceIdx(n1idx, oidx, 1.21)
        }
        else if (({atomIndex=targetIdx}.atomName == "C")
            and ({atomIndex=targetIdx}.group != "GLY")) {

            # Desired target location is tetragonal CB
            var cbidx = getCBidx(n1idx)
            pt = getTet(n2idx, n1idx, cbidx, 1.5)
        }
        else { # CA (or GLY C)

            # Save current target coords
            var cp = {atomIndex=targetIdx}.xyz

            # Set target atom at desired distance and angle
            select {atomIndex=targetIdx}
            setDistanceIdx(n1idx, targetIdx, 1.5)
            setAngleIdx(n2idx, n1idx, targetIdx, 120.0)
            if ({atomIndex=targetIdx}.atomName == "CA") {
                setDihedralIdx(n3idx, n2idx, n1idx, targetIdx, 180)
            }

            # Record and restore target
            pt = {atomIndex=targetIdx}.xyz
            {atomIndex=targetIdx}.xyz = cp
        }

        # If target not at desired location
        if (distance(pt, {atomIndex=targetIdx}) > kDtolerance) {
            okCount = 0
            gTargetPt = pt
            var xcount = 0
            gOK = FALSE
            while ((xcount < 20) and (gOK == FALSE)) {

                # Rotate on cWard rotor set to move it there
                tugTrackIdx(targetIdx, pt, FALSE, FALSE)
                    #(distance(pt, {atomIndex=targetIdx}) > kMtolerance))
                xcount++
            }
        }
        else {
            gOK = TRUE
            okCount++
        }

        # If successful
        if (gOK == TRUE) {

            # Adust any side atoms
            repairSideChain(targetIdx, FALSE)
        }

        # Else fail
        else {
            break
        }

        # If no movement in 4 tries, we are done
        if (okCount > 3) {
            break
        }
    } # endwhile (targetIdx != gCanchorIdx) {
}

# Rebuild Nward rotors set
function tugTrackN() {

    gOK = TRUE

    # For all bb atoms nWard of cargo
    var targetIdx = gNcargoIdx
    var okCount = 0

    # Allow collisions with cargo
    gOkCollide = gCargoSet
    var tcount = 0
    while (targetIdx != gNanchorIdx) {

        # Step to next atom
        targetIdx = getNwardBBidx(targetIdx)

        # No collision with cargo allowed after two atoms placed
        if (tcount == 2) {
           gOkCollide = ({})
        }
        tcount++

        # Compute targets desired coords
        var n1idx = getNwardBBidx(targetIdx)
        var c1idx = getCwardBBidx(targetIdx)
        var c2idx = getCwardBBidx(c1idx)
        var c3idx = getCwardBBidx(c2idx)
        var pt = {0 0 0}
        if ({atomIndex=targetIdx}.atomName == "CA") {

            # Desired target location is trigonal O
            var oidx = getOidx(c1idx)
            select {atomIndex=oidx}
            setDistanceIdx(c1idx, oidx, 1.39)
            pt = getTrigonal(c2idx, c1idx, oidx, 1.41)
            setDistanceIdx(c1idx, oidx, 1.21)
        }
        else if (({atomIndex=targetIdx}.atomName == "N")
            and ({atomIndex=targetIdx}.group != "GLY")) {

            # Desired target location is r-tetragonal CB
            var cbidx = getCBidx(c1idx)
            pt = getTet(cbidx, c1idx, c2idx, 1.5)
        }
        else { # C

            # Save current target coords
            var cp = {atomIndex=targetIdx}.xyz

            # Set target atom at desired distance and angle
            select {atomIndex=targetIdx}
            setDistanceIdx(c1idx, targetIdx, 1.37)
            setAngleIdx(c2idx, c1idx, targetIdx, 110.0)

            if ({atomIndex=targetIdx}.group == "PRO") {
                setDihedralIdx(c3idx, c2idx, c1idx, targetIdx, -57.0)
            }

            # Record and restore target
            pt = {atomIndex=targetIdx}.xyz
            {atomIndex=targetIdx}.xyz = cp
        }

        # If target not at desired location
        if (distance(pt, {atomIndex=targetIdx}) > kDtolerance) {
            var okCount = 0
            gTargetPt = pt
            var xcount = 0
            gOK = FALSE
            while ((xcount < 20) and (gOK == FALSE)) {

                # Rotate on cWard rotor set to move it there
                tugTrackIdx(targetIdx, pt, TRUE, FALSE)
                    #(distance(pt, {atomIndex=targetIdx}) > kMtolerance))
                xcount++
            }
        }
        else {
            gOK = TRUE
            okCount++
        }

        # If sucessful
        if (gOK == TRUE) {

            # Adust any side atoms
            repairSideChain(targetIdx, TRUE)
        }

        # Else fail
        else {
            break
        }

        # If no movement in 4 tries, we are done
        if (okCount > 3) {
            break
        }

    }   # endwhile (targetIdx != gNanchorIdx) {

}

# gPlicoRecord is maintained by the macro pilcoRecord
function plicoRecord(s) {
    var g = format("show file \"%s\"", gPlicoRecord)
    var ls = script(g)
    if (ls.find("FileNotFoundException")) {
        ls = ""
    }
    ls += s
    write var ls @gPlicoRecord
}

# gPlicoRecord is maintained by the macro pilcoRecord
function translateSelectedRecord(pt) {
    if (gPlicoRecord != "") {
        plicoRecord(format("select %s;translateSelected %s;", {selected}, pt))
    }
    translateSelected @pt
}

# gPlicoRecord is maintained by the macro pilcoRecord
function rotateSelectedRecord(g1pivotIdx, axis, a) {
    if (gPlicoRecord != "") {
        plicoRecord(format("select %s;", {selected}))
        plicoRecord(format("rotateSelected {atomIndex=%d} @%s @%s;",
            g1pivotIdx, axis, a))
    }
    rotateSelected {atomIndex=g1pivotIdx} @axis @a
}

function collectSCrotors(no, iChain) {
    var scBondIdxs = array()
    for (var iNo = no; iNo >= 0; iNo--) {
        var ile = 0
        switch ({(atomno=iNo) and (chain=iChain)}.atomName) {
        case "CA" :
            return scBondIdxs # Early exit since break 1 appears broken
        case "CZ" :
            if ({(atomno=iNo) and (chain=iChain)}.group == "TYR") {
                break
            }
        case "CE" :
            if ({(atomno=iNo) and (chain=iChain)}.group == "MET") {
                break
            }
        case "CG1" :
            if ({(atomno=iNo) and (chain=iChain)}.group == "VAL") {
                break
            }
            if ({(atomno=iNo) and (chain=iChain)}.group == "ILE") {
                ile = 1
            }
        case "NE" :
        case "CD" :
        case "SD" :
        case "CG" :
        case "CB" :
            scBondIdxs += {(atomno=@{iNo+1+ile}) and (chain=iChain)}.atomIndex
            scBondIdxs += {(atomno=@{iNo+0}) and (chain=iChain)}.atomIndex
            if ({(atomno=iNo) and (chain=iChain)}.atomName%2 == "CG") {
                scBondIdxs += {(atomno=@{iNo-1}) and (chain=iChain)}.atomIndex
                scBondIdxs += {(atomno=@{iNo-4}) and (chain=iChain)}.atomIndex
            }
            else if ({(atomno=iNo) and (chain=iChain)}.atomName == "CB") {
                scBondIdxs += {(atomno=@{iNo-3}) and (chain=iChain)}.atomIndex
                scBondIdxs += {(atomno=@{iNo-4}) and (chain=iChain)}.atomIndex
            }
            else {
                scBondIdxs += {(atomno=@{iNo-1}) and (chain=iChain)}.atomIndex
                scBondIdxs += {(atomno=@{iNo-2}) and (chain=iChain)}.atomIndex
            }
            break
        }

    }

    return scBondIdxs
}

# Drag Side Chain
function dragSC() {

    var iNo = {atomIndex=gSCidx}.atomno
    var iChain  = {atomIndex=gSCidx}.chain

    if ({atomIndex=gSCidx}.group != "PRO") {

        var scBondIdxs = collectSCrotors( iNo, iChain)
        var numChi = scBondIdxs.size / 4
        var dist = distance({atomIndex=gSCidx}.xyz, gSCpt)

        # For all rotor combinations
        var dh = array()
        for (var i = 0; i < numChi; i++) {
            dh += angle({atomIndex=@{scBondIdxs[4+(4*i)]}},
                {atomIndex=@{scBondIdxs[3+(4*i)]}},
                {atomIndex=@{scBondIdxs[2+(4*i)]}},
                {atomIndex=@{scBondIdxs[1+(4*i)]}})
        }
        for (var i = 0; i < numChi; i++) {
            var rot = -120
            for (var j = 0; j < 6; j++) {
                rot += 60*j
                selectAddSideChain(scBondIdxs[1+(4*i)])
                setDihedralIdx(scBondIdxs[4+(4*i)], scBondIdxs[3+(4*i)],
                    scBondIdxs[2+(4*i)], scBondIdxs[1+(4*i)], rot)
                var newDist = distance({atomIndex=gSCidx}.xyz, gSCpt)

                # Find the best
                if (newDist < dist) {
                    dist = newDist
                    for (var k = 0; k < numChi; k++) {
                        dh[k+1] = angle({atomIndex=@{scBondIdxs[4+(4*k)]}},
                        {atomIndex=@{scBondIdxs[3+(4*k)]}},
                        {atomIndex=@{scBondIdxs[2+(4*k)]}},
                        {atomIndex=@{scBondIdxs[1+(4*k)]}})
                    }
                }
            }
        }

        # Now set the best
        for (var i = 0; i < numChi; i++) {
            selectAddSideChain(scBondIdxs[1+(4*i)])
            setDihedralIdx(scBondIdxs[4+(4*i)], scBondIdxs[3+(4*i)],
                scBondIdxs[2+(4*i)], scBondIdxs[1+(4*i)], dh[i+1])
        }
    }
    else { # PRO - toggle between puckers up and down
        var icd = {(atomno=@{iNo+1}) and (chain=iChain)}.atomIndex
        var icb = {(atomno=@{iNo-1}) and (chain=iChain)}.atomIndex
        var ica = {(atomno=@{iNo-4}) and (chain=iChain)}.atomIndex
        var in = {(atomno=@{iNo-5}) and (chain=iChain)}.atomIndex
        select {atomIndex=gSCidx}

        if (angle({atomIndex=ica}, {atomIndex=in},
            {atomIndex=icd}, {atomIndex=gSCidx}) < -10.0) {
            setDihedralIdx(ica, in, icd, gSCidx, 8.7)
            setAngleIdx(in, icd, gSCidx, 110.0)
            setDistanceIdx(icd, gSCidx, 1.5)
        }
        else {
            setDihedralIdx(ica, in, icd, gSCidx, -29.5)
            setAngleIdx(in, icd, gSCidx, 108.8)
            setDistanceIdx(icd, gSCidx, 1.5)
        }
    }

    draw gSCcircle CIRCLE {atomIndex=gSCidx} MESH NOFILL
    gSCpt = {atomIndex=gSCidx}.xyz
}

# Fix side chain collisions
function fixSCcollision2(idx) {
    gOk2 = FALSE
    var iNo = {atomIndex=idx}.atomno
    var iChain = {atomIndex=idx}.chain
    var resno = {(atomno=iNo) and (chain=iChain)}.resno

    # Get SC terminus
    while (resno == {(atomno=iNo) and (chain=iChain)}.resno) {
        iNo++
    }
    iNo--

    var sc = array()
    var iBno = iNo
    while ({(atomno=iBno) and (chain=iChain)}.atomName != "CB") {
        sc += {(atomno=iBno) and (chain=iChain)}
        iBno--
    }
    var cbidx = {(atomno=iBno) and (chain=iChain)}.atomIndex

    var scBondIdxs = collectSCrotors( iNo, iChain)
    var numChi = scBondIdxs.size / 4

    # For all rotor combinations
    for (var i = 0; i < numChi; i++) {
        var rot = -120
        for (var j = 0; j < 6; j++) {
            rot += 60
            selectAddSideChain(scBondIdxs[1+(4*i)])
            setDihedralIdx(scBondIdxs[1+(4*i)], scBondIdxs[2+(4*i)],
                scBondIdxs[3+(4*i)], scBondIdxs[4+(4*i)], rot)
                
            # If no collision, exit
            colliders = (within(kCtolerance, FALSE, {sc})
                and not {atomIndex=cbidx} and not {sc})

            # If it is with water, delete the water
            for (var c = 1; c < colliders.size; c++ ) {
                if (colliders[c].group = "HOH") {
                    delete {atomIndex=@{colliders[c].atomIndex}}
                    colliders = {colliders and not @{colliders[c]}}
                }
            }

            if (colliders.size == 0) {
                gOk2 = TRUE
                return # Early exit since break 1 appears broken
            }

        }
    }
}

function isMovableSideChain(aIdx) {

    var ret = (({atomIndex=aIdx}.group != "PRO")
        or ({atomIndex=aIdx}.atomName == "CG"))
    switch({atomIndex=aIdx}.atomName) {
    case "N":
    case "CA":
    case "C":
    case "CB":
    case "O":
    case "O4\'":
        ret = FALSE
        break
    }
    return ret
}

# gFreeze is maintained by the script plicoFreeze that allows the user
# to inhibit rotation on selected rotors
function isRotorAvailable(idx) {
    return (gFreeze.find(idx) == 0)
}

function collectBBrotors(nWard) {
    var anchorNo = (nWard
        ? ((gNanchorIdx >= 0) ? {atomIndex=gNanchorIdx}.atomno : gMinNo)
        : ((gCanchorIdx >= 0) ? {atomIndex=gCanchorIdx}.atomno : gMaxNo))
    var cargoNo = (nWard
        ? ((gNcargoIdx >= 0) ? {atomIndex=gNcargoIdx}.atomno
        : {atomIndex=gCcargoIdx}.atomno)
        : {atomIndex=gCcargoIdx}.atomno)
    var rotors = array()
    if (cargoNo < anchorNo) {

        for (var iNo = cargoNo; iNo <= anchorNo; iNo++) {
            if ({(atomno=iNo) and (chain=gChain)}.atomName == "CA") {
                if (isRotorAvailable(iNo)) {
                    if (({(atomno=iNo) and (chain=gChain)}.group != "PRO") and (iNo > cargoNo)) { # phi
                        rotors += [{(atomno=@{getCmNo(iNo-1)}) and (chain=gChain)}.atomIndex,
                            {(atomno=@{iNo-1}) and (chain=gChain)}.atomIndex]
                        rotors += [{(atomno=@{iNo}) and (chain=gChain)}.atomIndex,
                            {(atomno=@{iNo+1}) and (chain=gChain)}.atomIndex]
                    }
                    if (iNo != (anchorNo-1)) { # psi
                        rotors += [{(atomno=@{iNo-1}) and (chain=gChain)}.atomIndex,
                            {(atomno=@{iNo}) and (chain=gChain)}.atomIndex]
                        rotors += [{(atomno=@{iNo+1}) and (chain=gChain)}.atomIndex,
                            {(atomno=@{getNpNo(iNo+2)}) and (chain=gChain)}.atomIndex]
                    }
                }
            }
        }
    }
    else {

        for (var iNo = cargoNo; iNo >= anchorNo; iNo--) {
            if ({(atomno=iNo) and (chain=gChain)}.atomName == "CA") {
                if (isRotorAvailable(iNo)) {
                    if ((iNo != (anchorNo-1)) and (iNo < cargoNo)) { # psi
                        rotors += [{(atomno=@{getNpNo(iNo+2)}) and (chain=gChain)}.atomIndex,
                            {(atomno=@{iNo+1}) and (chain=gChain)}.atomIndex]
                        rotors += [{(atomno=@{iNo}) and (chain=gChain)}.atomIndex,
                            {(atomno=@{iNo-1}) and (chain=gChain)}.atomIndex]
                    }
                    if ({(atomno=iNo) and (chain=gChain)}.group != "PRO") { # phi
                        rotors += [{(atomno=@{iNo+1}) and (chain=gChain)}.atomIndex,
                            {(atomno=@{iNo}) and (chain=gChain)}.atomIndex]
                        rotors += [{(atomno=@{iNo-1}) and (chain=gChain)}.atomIndex,
                            {(atomno=@{getCmNo(iNo-1)}) and (chain=gChain)}.atomIndex]
                    }
                }
            }
        }
    }

    if (nWard) {
        gNrotors = rotors
    }
    else {
        gCrotors = rotors
    }
}

function collectRotors() {
    collectBBrotors(FALSE)
    collectBBrotors(TRUE)
}

function tugSideChain(pt) {

    # If destination atom defined
    if (gDestAtomIdx >= 0) {
        var v = {atomIndex=gDestAtomIdx}.xyz - {atomIndex=gSCidx}.xyz
        if (abs(angle({atomIndex=gDestAtomIdx}.xyz, {0 0 0}, pt)) < 90) {
            pt = -v/20.0
        }
        else {
            pt = v/20.0
        }
    }
    gSCpt += pt
    draw arrow {atomIndex=gSCidx} @gSCpt
}

function setColors() {
    select all
    color {selected} @gScheme
    color {atomIndex=g1pivotIdx} green
    color {atomIndex=g2pivotIdx} green
    color @gCargoSet @gAltScheme
    select {(atomIndex=gCcargoIdx) or (atomIndex=gNcargoIdx)
        or (atomIndex=gCanchorIdx) or (atomIndex=gNanchorIdx)}
    halo on
    select {atomIndex=gDestAtomIdx}
    star on
    select none
}

function clearAtomIdxs() {
    gCcargoIdx = -1
    gNcargoIdx = -1
    gCanchorIdx = -1
    gNanchorIdx = -1
    g1pivotIdx = -1
    g2pivotIdx = -1
    gDestAtomIdx = -1
    gSCidx = -1
}

function timedOut (s) {
    timeout ID"tug" OFF
    prompt(s)
    gBusy = FALSE
    background ECHO yellow
    restore state gState
    select gCargoSet
    refresh
    quit
}

function recordDrag() {
    var ls = format("select %s;", {selected})
    ls += format("gCanchorIdx = %d;", gCanchorIdx)
    ls += format("gCanchorNo = %d;", gCanchorNo)
    ls += format("gNanchorIdx = %d;", gNanchorIdx)
    ls += format("gNanchorNo = %d;", gNanchorNo)
    ls += format("gCcargoIdx = %d;", gCcargoIdx)
    ls += format("gNcargoIdx = %d;", gNcargoIdx)
    ls += format("gCcargoNo = %d;", gCcargoNo)
    ls += format("gNcargoNo = %d;", gNcargoNo)
    ls += format("gDestAtomIdx = %d;", gDestAtomIdx)
    ls += format("g1pivotIdx = %d;", g1pivotIdx)
    ls += format("g2pivotIdx = %d;", g2pivotIdx)
    ls += format("gOkCollide = %s;", gOkCollide)
    ls += format("gChain = \"%s\";", gChain)
    ls += format("gMinNo = %d;", gMinNo)
    ls += format("gMaxNo = %d;", gMaxNo)
    ls += format("gCargoSet = %s;", gCargoSet)
    ls += format("gSCidx = %d;", gSCidx)
    ls += format("gSCcircle = %d;", gSCcircle)
    ls += format("gSCpt = %s;", gSCpt)
    ls += "collectRotors();"
    ls += "tugDragDoneMB();"
    plicoRecord(ls)
}

# Bound to LEFT-UP by tugEnableDrag
function tugDragDoneMB() {
    if (gBusy == FALSE) {
        if (gPlicoRecord != "") {
            recordDrag()
        }

        # Move by rotation on rotor sets, smallest first
        gBusy = TRUE
        background ECHO pink
        refresh

        # If side chain mode
        if (gSCidx >= 0) {
            dragSC()
        }

        # Else
        else if (not gTow) {
            gOK = TRUE
            timeout ID"tug" 20.0 "timedOut(\"Tug timed out\")"
            if ((gCrotors.size < gNrotors.size) or (gNanchorIdx < 0)) {
                if (gCrotors.size > 4) {
                    tugTrackC()  # PULLSTRING MODEL
                }
                if (gOK and (gNrotors.size > 4)) {
                    tugTrackN()  # PULLSTRING MODEL
                }
            }
            else {
                if (gNrotors.size > 4) {
                    tugTrackN()  # PULLSTRING MODEL
                }
                if (gOK and (gCrotors.size > 4)) {
                    tugTrackC()  # PULLSTRING MODEL
                }
            }
            timeout ID"tug" OFF

            # If anchor angles acute, fail
            if (gOK == TRUE) {
                if (gCanchorIdx >= 0) {
                    var ic = getCwardBBidx(gCanchorIdx)
                    var in = getNwardBBidx(gCanchorIdx)
                    if ((ic >= 0) and
                        angle({atomIndex=ic}, {atomIndex=gCanchorIdx}, {atomIndex=in})
                        < 100.0) {
                        gOK = FALSE
                    }
                }
                if (gNanchorIdx >= 0) {
                    var ic = getCwardBBidx(gNanchorIdx)
                    var in = getNwardBBidx(gNanchorIdx)
                    if ((in >= 0) and
                        angle({atomIndex=ic}, {atomIndex=gNanchorIdx}, {atomIndex=in})
                        < 100.0) {
                        gOK = FALSE
                    }
                }
            }

            # If too far
            if (gOK == FALSE) {
                timedOut("TUG TOO FAR!")
            }

            # Else OK
            else {

                select ((atomno >= gNanchorNo) and (atomno <= gCanchorNo)
                    and (chain = gChain))
                var idx = {(atomno=@{{chain=gChain}.atomno.min})
                    and (chain=gChain)}.atomIndex


                var ihc = 0
                for (ihc = 0; ihc < 10; ihc++) {
                    handleCollisions2(FALSE, idx)
                    if (countCollisions(({})) == 0) {
                        break
                    }
                }
                if (ihc == 10) {
                    var p = prompt("Unable to handle all collisions!")
                    restore state gState
                }
            }
        }
        select {gCargoSet}
        gBusy = FALSE
        background ECHO yellow
        refresh
    }
}

# Bound to ALT-SHIFT-LEFT-DRAG by tugEnableDrag
function tugDrag2MB() {
    tugDragMB(TRUE)
}

# Bound to ALT-LEFT-DRAG by tugEnableDrag
function tugDragMB(alt) {
    if (gBusy == FALSE) {
        gBusy = TRUE
        var dx = (40.0 * (_mouseX - gMouseX))/_width
        var dy = (40.0 * (_mouseY - gMouseY))/_height
        var q = quaternion()
        var ptd = {@dx @dy 0}
        var pt = (!q)%ptd
        var axis = {0 0 0}
        if (distance(pt,  {0 0 0}) > 0.004) {
            # If sidechain mode
            if (gSCidx >= 0) {
                if ({atomIndex=gSCidx}.atomName == "O") {
                    dir = ((abs(dx) > abs(dy))
                        ? ((dx < 0) ? 2 : -2)
                        : ((dy < 0) ? 2 : -2))
                    counterRotate(gSCidx, dir, not alt)
                }
                else {
                    tugSideChain(pt)
                }
            }

            # Else
            else {

                # If new drag
                if (gNewDrag) {
                    gNewDrag = FALSE
                    save state gState
                }

                # If destination atom defined
                if (gDestAtomIdx >= 0) {
                    var v = {atomIndex=gDestAtomIdx}.xyz - {selected}.xyz
                    if (abs(angle({atomIndex=gDestAtomIdx}.xyz, {0 0 0}, pt)) < 90) {
                        pt = -v/20.0
                    }
                    else {
                        pt = v/20.0
                    }
                }

                # Move the cargo
                select {gCargoSet}

                # If pivots defined, rotate it
                if (g1pivotIdx >= 0) {

                    # If two pivots
                    if (g2pivotIdx >= 0) {
                        axis = {atomIndex=g2pivotIdx}
                    }

                    # Else
                    else {
                        axis = cross(pt, {0 0 0}) + {atomIndex=g1pivotIdx}.xyz
                    }

                    dir = ((abs(dx) > abs(dy))
                        ? ((dx < 0) ? 2 : -2)
                        : ((dy < 0) ? 2 : -2))
                    rotateSelectedRecord(g1pivotIdx, axis, dir)

                }

                # Else translate it
                else {
                    translateSelectedRecord(pt)
                }

                # If collisions
                var cNotSels = (within(kCtolerance, FALSE, {selected})
                    and not {gMovingSet})
                if (cNotSels.size > 0) {
                    gOk2 = TRUE
                    for (var i = 1; i <= cNotSels.size;  i++) {

                        # If net collision vector same as move vector
                        cSels = (within(kCtolerance, FALSE, cNotSels[i]) and {selected})
                        for (var j = 1; j <= cSels.size;  j++) {
                            var v1 = cNotSels[i].xyz - cSels[j].xyz
                            if (abs(angle(v1, {0 0 0}, pt)) < 90) {

                                # If tow mode
                                if (gTow) {

                                    # Make a dynamic pivot
                                    if (g1pivotIdx < 0) {
                                        g1pivotIdx = cSels[j].atomIndex
                                        g1dynamicIdx = cNotSels[i].atomIndex
                                        color {atomIndex=g1pivotIdx} lightgreen
                                        setDistanceIdx(cNotSels[i].atomIndex,
                                            cSels[j].atomIndex,
                                            kCtolerance + kDtolerance)
                                    }
                                    else if (g2pivotIdx < 0) {
                                        g2pivotIdx = cSels[j].atomIndex
                                        g2dynamicIdx = cNotSels[i].atomIndex
                                        color {atomIndex=g2pivotIdx} lightgreen
                                        setDistanceIdx(cNotSels[i].atomIndex,
                                            cSels[j].atomIndex,
                                            kCtolerance + kDtolerance)
                                    }
                                    else {
                                        gOk2 = FALSE
                                    }
                                }
                                else {

                                    # Try to resolve
                                    select cSels[j]
                                    var idx = {(atomno=@{{chain=gChain}.atomno.min})
                                        and (chain=gChain)}.atomIndex
                                    handleCollisions2(FALSE, idx)
                                }
                            }
                        } # endfor
                        if (gOk2 == FALSE) {
                            break
                        }
                    } # endfor

                    # If unable and not alt
                    if ((gOk2 == FALSE) and (not alt)) {

                        # Back off
                        background ECHO pink
                        delay 1
                        if (g1pivotIdx >= 0) {
                            rotateSelectedRecord(g1pivotIdx, axis, -a)
                        }
                        else {
                            translateSelectedRecord(-pt)
                        }
                        background ECHO yellow
                    }
                }
            }

            # If dynamic pivotsTBD
            if (g1dynamicIdx >= 0) {
                var v1 = {atomIndex=g1dynamicIdx}.xyz - {atomIndex=g1pivotIdx}.xyz
                if (abs(angle(v1, {0 0 0}, pt)) > 90) {
                    color {atomIndex=g1pivotIdx} @gAltScheme
                    g1pivotIdx = -1
                    g1dynamicIdx = -1

                }
            }
            if (g2dynamicIdx >= 0) {
                var v1 = {atomIndex=g2dynamicIdx}.xyz - {atomIndex=g2pivotIdx}.xyz
                if (abs(angle(v1, {0 0 0}, pt)) > 90) {
                    color {atomIndex=g2pivotIdx} @gAltScheme
                    g2pivotIdx = -1
                    g2dynamicIdx = -1
                }
            }

            gMouseX = _mouseX
            gMouseY = _mouseY
        }
        select {gCargoSet}
        gBusy = FALSE
    }
}

# Bound to ALT-LEFT-DOWN by tugEnableDrag
function tugMarkMB() {
    gMouseX = _mouseX
    gMouseY = _mouseY
    gNewDrag = TRUE
}

# Called by tugCargoMB
function tugEnableDrag() {
    gEcho = "__________TUG__________|ALT-CLICK=mark block|SHIFT-CLICK=anchors" +
        "|ALT-CTRL-CLICK=pivots|ALT-SHIFT-CLICK=dest atom|ALT-DRAG=move" +
        "|SHIFT-ALT-DRAG=alt move|DOUBLE-CLICK=exit"
    echo @gEcho

    # Allow atoms to be dragged
    bind "ALT-LEFT-DOWN" "tugMarkMB";
    bind "ALT-LEFT-UP" "tugDragDoneMB";
    bind "ALT-LEFT-DRAG" "tugDragMB";
    bind "ALT-SHIFT-LEFT-DRAG" "tugDrag2MB";

    unbind "SHIFT-LEFT-CLICK"
    bind "SHIFT-LEFT-CLICK" "_pickAtom";
    bind "SHIFT-LEFT-CLICK" "+:tugAnchorMB";

    bind "ALT-CTRL-LEFT-CLICK" "_pickAtom";
    bind "ALT-CTRL-LEFT-CLICK" "+:tugPivotMB";

    bind "ALT-SHIFT-LEFT-CLICK" "_pickAtom";
    bind "ALT-SHIFT-LEFT-CLICK" "+:tugDestAtomMB";
}

# Bound to SHIFT-LEFT-CLICK by tugCargoMB
function tugAnchorMB() {
    if ({atomIndex=_atomPicked}.chain == gChain) {
        var aPidx = getScBBidx( _atomPicked)

        var pno = {atomIndex=aPidx}.atomno
        if (pno > {atomIndex=gCcargoIdx}.atomno) {
            select {atomIndex=gCanchorIdx}
            halo off
            if (gCanchorIdx == aPidx) {
                gCanchorIdx = -1
                gCanchorNo = gMaxNo + 1
            }
            else {
                gCanchorIdx = aPidx
                gCanchorNo = {atomIndex=gCanchorIdx}.atomno
                select {atomIndex=gCanchorIdx}
                halo on
            }
            collectBBrotors(FALSE)
        }
        else if (pno < {atomIndex=gNcargoIdx}.atomno) {
            select {atomIndex=gNanchorIdx}
            halo off
            if (gNanchorIdx == aPidx) {
                gNanchorIdx = -1
                gNanchorNo = gMinNo - 1
            }
            else {
                gNanchorIdx = aPidx
                gNanchorNo = {atomIndex=gNanchorIdx}.atomno
                select {atomIndex=gNanchorIdx}
                halo on
            }
            collectBBrotors(TRUE)
        }
        else {
            towCargoMB()
        }

        # Get moving atoms set
        gMovingSet = {((atomno < gCanchorNo) and (atomno > gNanchorNo)
            and (chain=gChain))}
    }
    select {gCargoSet}
}

# Bound to ALT-SHIFT-LEFT-CLICK by tugCargoMB
function tugDestAtomMB() {
    var aOk = TRUE
    if ({atomIndex=_atomPicked}.chain == gChain) {

        var pno = {atomIndex=_atomPicked}.atomno
        if ((pno <= {atomIndex=gCcargoIdx}.atomno) and (pno >= {atomIndex=gNcargoIdx}.atomno)) {
            aOk = FALSE
        }
    }
    if (aOk) {
        select {atomIndex=gDestAtomIdx}
        star off
        if (gDestAtomIdx == _atomPicked) {
            gDestAtomIdx = -1
        }
        else {
            gDestAtomIdx = _atomPicked
            select {atomIndex=gDestAtomIdx}
            star on
        }
        select {gCargoSet}
    }
}

# Bound to CTRL-LEFT-CLICK by tugCargoMB
function tugPivotMB() {
    if (g1pivotIdx == _atomPicked) {
        color {atomIndex=g1pivotIdx} @gScheme
        if (g2pivotIdx >= 0) {
            g1pivotIdx = g2pivotIdx
            g2pivotIdx = -1
        }
        else {
            g1pivotIdx = -1
        }
    }
    else if (g2pivotIdx == _atomPicked) {
        color {atomIndex=g2pivotIdx} @gScheme
        g2pivotIdx = -1
    }
    else if (g1pivotIdx >= 0) {
        if (g2pivotIdx >= 0) {
            color {atomIndex=g2pivotIdx} @gScheme
        }

        g2pivotIdx = _atomPicked
        color {atomIndex=g2pivotIdx} green
    }
    else {
        g1pivotIdx = _atomPicked
        color {atomIndex=g1pivotIdx} green
    }
    select {gCargoSet}
}

# Bound to SHIFT-LEFT-CLICK by plicoTug
function towCargoMB() {
    gTow = TRUE
    gChain = {atomIndex=_atomPicked}.chain
    gMinNo = {chain=gChain}.atomno.min
    gMaxNo = {chain=gChain}.atomno.max
    gCcargoIdx = -1
    gNcargoIdx = -1
    gCanchorIdx = -1
    gCanchorNo = gMaxNo + 1
    gNanchorIdx = -1
    gNanchorNo = gMinNo - 1

    # Highlight cargo cluster
    select {chain=gChain}
    gCargoSet = {selected}
    gMovingSet = {selected}
    setColors()

    # Enable dragging
    tugEnableDrag()
    select {gCargoSet}
    halo off
    var es = gEcho.replace("anchors","mark chain")
    echo @es
    unbind "SHIFT-LEFT-CLICK"
    bind "SHIFT-LEFT-CLICK" "_pickAtom";
    bind "SHIFT-LEFT-CLICK" "+:towCargoMB";
}

# Bound to ALT-LEFT-CLICK by plicoTug
function tugCargoMB() {

    # If O or movable side chain atom picked
    if (({atomIndex=_atomPicked}.atomName = "O")
        or (isMovableSideChain( _atomPicked))) {
        if (gSCidx >= 0) {
            draw gSCcircle DELETE
        }
        if (gSCidx == _atomPicked) {
            gSCidx = -1
        }
        else {
            gSCidx = _atomPicked
            gSCpt = {atomIndex=gSCidx}.xyz
            draw gSCcircle CIRCLE {atomIndex=gSCidx} MESH NOFILL
        }
    }
    else {
        if ({atomIndex=_atomPicked}.chain != gChain) {
            if (gTow) {
                select {chain=gChain}
                color {selected} @gScheme
            }
            gChain = {atomIndex=_atomPicked}.chain
            select ({atomIndex=gCcargoIdx} or {atomIndex=gNcargoIdx}
                or {atomIndex=gCanchorIdx} or {atomIndex=gNanchorIdx})
            halo off
            gCcargoIdx = -1
            gNcargoIdx = -1
            gCanchorIdx = -1
            gNanchorIdx = -1
        }
        gTow = FALSE
        gMinNo = {chain=gChain}.atomno.min
        gMaxNo = {chain=gChain}.atomno.max
        if (gNanchorIdx < 0) {
            gNanchorNo = gMinNo - 1
        }
        if (gCanchorIdx < 0) {
            gCanchorNo = gMaxNo + 1
        }
        var aPidx = getScBBidx( _atomPicked)

        gSCidx = -1
        draw gSCcircle DELETE

        # If existing cWard cargo picked
        if (gCcargoIdx == aPidx) {

            # Clear the highlight
            select {atomIndex=gCcargoIdx}
            halo off

            # If nWard cargo exists, mark it as the cWard cargo
            if (gNcargoIdx != gCcargoIdx) {
                gCcargoIdx = getCpIdx(gNcargoIdx)
                gCcargoNo = {atomIndex=gCcargoIdx}.atomno
            }
            else {
                gCcargoIdx = -1
                gNcargoIdx = -1
            }
        }
        else if (gNcargoIdx == aPidx) {
            select {atomIndex=gNcargoIdx}
            halo off
            gNcargoIdx = getNmIdx(gCcargoIdx)
            gNcargoNo = {atomIndex=gNcargoIdx}.atomno
        }
        else if (gCcargoIdx >= 0) {

            var no = {atomIndex=aPidx}.atomno

            # If pick is nWard of it
            if (no < {atomIndex=gCcargoIdx}.atomno) {

                # If exists, clear its highlight
                if (gNcargoIdx != gCcargoIdx) {
                    select {atomIndex=gNcargoIdx}
                    halo off
                }

                # Set new nWard cargo and highlight it
                gNcargoIdx = getNmIdx(aPidx)
                gNcargoNo = {atomIndex=gNcargoIdx}.atomno
            }

            # Else cWard
            else {

                # Clear its old highlight
                select {atomIndex=gCcargoIdx}
                if (gNcargoIdx != gCcargoIdx) {
                    halo off
                }

                # Set new cWard cargo and highlight
                gCcargoIdx = getCpIdx(aPidx)
                gCcargoNo = {atomIndex=gCcargoIdx}.atomno
            }
        }

        # Else no cWard cargo
        else {

            # Set new cWard cargo and highlight
            gCcargoIdx = getCpIdx(aPidx)
            gCcargoNo = {atomIndex=gCcargoIdx}.atomno
            gNcargoIdx = getNmIdx(gCcargoIdx)
            gNcargoNo = {atomIndex=gNcargoIdx}.atomno

            # Set default cWard anchor at cWard N
            var iNo = gMaxNo
            for (; iNo > 0; iNo--) {
                if ({(atomno=iNo) and (chain=gChain)}.atomName == "N") {
                    break;
                }
            }
            gCanchorIdx = {(atomno=iNo) and (chain=gChain)}.atomIndex
            gCanchorNo = {atomIndex=gCanchorIdx}.atomno
        }

        # If any anchor now inside cargo cluster, kill it
        if ({atomIndex=gCanchorIdx}.atomno <= {atomIndex=gCcargoIdx}.atomno) {
            gCanchorIdx = -1
            gCanchorNo = gMaxNo + 1
        }
        if ({atomIndex=gNanchorIdx}.atomno >= {atomIndex=gNcargoIdx}.atomno) {
            gNanchorIdx = -1
            gNanchorNo = gMinNo - 1
        }

        # Highlight cargo cluster
        selectNwardIdx(gCcargoIdx, gNcargoIdx)
        gCargoSet = {selected}
        setColors()

        # Collect the rotor sets
        collectRotors()

        # Get moving atoms set
        gMovingSet = {((atomno < gCanchorNo) and (atomno > gNanchorNo)
            and (chain=gChain))}
    }

    # Enable dragging
    tugEnableDrag()

    select {gCargoSet}
}

# Top level of Tug
function plicoTug() {

    # Bad idea to proceed when collisions present
    var cc = countCollisions(({}))
    if (cc > 0) {
        var p = prompt(format("%d collision%s present! Proceed anyway?",
            cc, ((cc > 1) ? "s" : "")), "OK|Cancel", TRUE)
        if (p == "Cancel") {
            quit
        }
    }

    # Push selected
    gSelSaves = {selected}
    select all
    gZoom = script("show zoom")
    gRotate = script("show rotation")
    write tugsave.pdb
    select none

    gScheme = defaultColorScheme
    gAltScheme = ((gScheme == "Jmol") ? "Rasmol" : "Jmol")
    set echo TOP LEFT
    background ECHO yellow
    gEcho = ("_________TUG_________|ALT-CLICK=mark block|SHIFT-CLICK=mark chain" +
        "|DOUBLE-CLICK=exit")
    echo @gEcho
    gCrotors = array()
    gNrotors = array()
    clearAtomIdxs()
    gChain = ""
    unbind

    bind "ALT-LEFT-CLICK" "_pickAtom";
    bind "ALT-LEFT-CLICK" "+:tugCargoMB";
    bind "SHIFT-LEFT-CLICK" "_pickAtom";
    bind "SHIFT-LEFT-CLICK" "+:towCargoMB";
    bind "DOUBLE" "tugExit";
}

# Bound to DOUBLE by plicoTug
function tugExit() {
    var p = prompt("Exit tug?", "Yes|No|Undo", TRUE)
    if (p == "Undo") {
        load tugsave.pdb
        script inline gZoom
        rotate @gRotate
        echo Tug session undone
        if (gPlicoRecord != "") {
            plicoRecord("load tugsave.pdb;")
        }
    }
    if (p != "No") {
        unbind
        halo off
        set allowMoveAtoms FALSE
        echo
        select all
        halo off
        star off
        color {selected} @gScheme
        draw gSCcircle DELETE
        gBusy = FALSE
        background ECHO yellow

        # Pop selected
        select gSelSaves
    }
}
# End of TUG.SPT

Contributors

Remig