This node implements the TwistSpline, which is a dynamically re-parameterizing bezier spline that interpolates twist along its length.
This TwistSpline can have any number of Control Vertices, and each control vertex has an incoming and outgoing tangent. The incoming tangent is ignored for the first CV, and the outgoing tangent is ignored for the last CV.
The OutputSpline plug is a custom type specific to this set of nodes.
The per-CV plugs control how the spline behaves and reparameterizes. The ControlVertex plug recieves the worldpace position and orientation of the CV itself. The InTangent and OutTangent are world matrices that define the bezier tangent positions and orientations for this CV. ParamValue and ParamWeight are used as a pair. ParamValue is the parameter that the currentCV will have when ParamWeight is 1.0. If ParamWeight is 0.0, then the parameter of this CV will float between it's neighbor's parameters (as a percentage of the lengths of its neighboring bezier spline segments). The parameterization algorithm works as long as any paramWeight is greater than 0.
TwistValue and TwistWeight work in a similar way. Twists are interpolated between values that have weight, and skip those that don't. Because this is handled as an interpolated float value, twist behavior allows for arbitrary values, and can twist past 360deg multiple times along the spline.
UseOrient is the "weight" of the ControlVertex worldspace orientation as part of the twist. Because of the limitations of Matrices and Quaternions, you can never get more than a 180 degree twist using orient behavior and popping can occur if you're not careful.
DebugDisplay and DebugScale show the orientation frames calculated along the spline and control their size.
The twistMultipler plug exists for backwards compatibility with bug in earlier versions of the code. The old multi-node auto-tangent setup accidentally built a left-handed twist matrix, thus the twist values went the wrong way. The new single-node auto-tangent builds the correct matrices, and thus this multipler must be set to 1.0 in that case.
ScaleCompensation exists because each input parameter would need a multipler attached to it to allow uniform scaling without changing behavior. This plug and the one on the rider handles all of that internally.
| Long Name (short name) | Type | Default |
|---|---|---|
| outputSpline (os) | TwistSpline | n/a |
___The custom spline data output |
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| outputNurbsCurve (onc) | NurbsCurve | n/a |
___A Maya-native NURBS curve output. Note: It will reparameterize by length, but it will not include twist data |
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| splineLength (sl) | double | 0.0 |
___The total length of the spline |
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| scaleCompensation (sclcmp) | double | 1.0 |
___The overall scale of the spline. This is required to make riding/pinning/offsets work correctly |
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| splineDisplay (sd) | bool | True |
___Whether to draw the spline |
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| debugDisplay (dd) | bool | False |
___Whether to show the debug axes |
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| debugScale (ds) | double | 1.0 |
___The size of the debug axes |
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| twistMultiplier (tm) | double | -1.0 |
___A multiplier on top of the intput TwistValue inputs. Exists for backwards compatibility |
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| vertexData (vd) | compound | n/a |
| ___Inputs for all of the per-cv data | ||
| ___inTangent (int) | matrix | Identity |
______The bezier tangent pointing towards the start of the spline |
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| ___outTangent (ot) | matrix | Identity |
______The bezier tangent pointing towards the end of the spline |
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| ___controlVertex (cv) | matrix | Identity |
______The control vertex |
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| ___paramValue (pv) | double | 0.0 |
______The parameter value of this CV |
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| ___paramWeight (pw) | double | 0.0 |
______Whether to use the paramValue, or float |
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| ___twistValue (tv) | double | 0.0 |
______The twist value of this CV |
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| ___twistWeight (tw) | double | 0.0 |
______Whether to use the twist value, or interpolate |
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| ___useOrient (uo) | double | 0.0 |
______Whether to use the orientation of this CV as part of the twist |
This node controls the behavior of all automatic bezier tangents for a control.
| Long Name (short name) | Type | Default |
|---|---|---|
| vertData (vd) | compound | n/a |
___ The input vertex user data |
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| ___vertMat (vm) | matrix | Identity |
______ The Control Vertex world matrix input |
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| ___inParentInverseMatrix (ipim) | matrix | Identity |
______ The parentInverseMatrix of the inTangent |
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| ___outParentInverseMatrix (opim) | matrix | Identity |
______ The parentInverseMatrix of the outTangent |
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| ___twistParentInverseMatrix (tpim) | matrix | Identity |
______ The parentInverseMatrix of the twist axis |
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| ___inTanWeight (itw) | double | 1.0 |
______The Length of the in auto tangent. A weight of 1 is 1/3 of the distance between the current and next CVs |
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| ___outTanWeight (otw) | double | 1.0 |
______The Length of the out auto tangent. A weight of 1 is 1/3 of the distance between the current and next CVs |
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| ___inSmooth (ism) | double | 1.0 |
______ Whether an automatic in tangent is smooth or linear |
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| ___outSmooth (osm) | double | 1.0 |
______ Whether an automatic out tangent is smooth or linear |
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| ___inAuto (iat) | double | 1.0 |
______ Whether or not the output is controlled automatically by the CVs |
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| ___outAuto (oat) | double | 1.0 |
______ Whether or not the output is controlled automatically by the CVs |
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| ___inTanMat (itm) | matrix | Identity |
______ The worldspace rest position of the inTangent |
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| ___outTanMat (otm) | matrix | Identity |
______ The worldspace rest position of the outTangent |
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| startTension (st) | double | 2.0 |
___ How much the first tangent overshoots |
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| endTension (et) | double | 2.0 |
___ How much the last tangent overshoots |
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| maxVertices (mv) | Int | 999 |
___ The maximum number of vertices that will be calculated |
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| closed (cl) | Bool | False |
___ Whether or not the tangents behave as a closed loop |
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| vertTans (vt) | compound | |
___ The output tangent data |
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| ___inVertTan (ivt) | double3 | n/a |
______ The output inTangent |
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| ______inVertTanX (ivx) | double | 0.0 |
_________ The output inTangent X component |
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| ______inVertTanY (ivy) | double | 0.0 |
_________ The output inTangent Y component |
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| ______inVertTanZ (ivz) | double | 0.0 |
_________ The output inTangent Z component |
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| ___outVertTan (ovt) | double3 | n/a |
______ The output outTangent |
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| ______outVertTanX (ovx) | double | 0.0 |
_________ The output outTangent X component |
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| ______outVertTanY (ovy) | double | 0.0 |
_________ The output outTangent Y component |
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| ______outVertTanZ (ovz) | double | 0.0 |
_________ The output outTangent Z component |
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| ___inTanLen (itl) | double | 0.0 |
______ The computed length of the inTangent |
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| ___outTanLen (otl) | double | 0.0 |
______ The computed length of the outTangent |
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| ___twistUp (tu) | double3 | n/a |
______ The direction of "up" for the twist axis |
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| ______twistUpX (tux) | double | 0.0 |
_________ The direction of "up" for the twist axis X component |
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| ______twistUpY (tuy) | double | 0.0 |
_________ The direction of "up" for the twist axis Y component |
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| ______twistUpZ (tuz) | double | 0.0 |
_________ The direction of "up" for the twist axis Z component |
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| ___twistMat (tm) | matrix | Identity |
______ The matrix for the twist axis that will keep it aligned with the auto tangents |
This node Controls the behavior of a single bezier tangent control.
This node assumes the tangent being controlled is an outgoing tangent. So for incoming tangents, the "previous" and "next" cvs are swapped.
These nodes usually come in pairs. One for each twist spline segment. The in/out linear targets are connected in a cycle between them. Don't worry, it's not an actual cycle as the plugs aren't connected that way internally to the node.
| Long Name (short name) | Type | Default |
|---|---|---|
| out (out) | double3 | n/a |
___The final output from this node. Usually connected to a tangent input on a TwistSpline node |
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| ___outX (ox) | double | 0.0 |
______The output X component |
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| ___outY (oy) | double | 0.0 |
______The output Y component |
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| ___outZ (oz) | double | 0.0 |
______The output Z component |
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| smoothTan (st) | double3 | n/a |
___The pure smooth tangent in un-oriented CV space. Not affected by weight or auto |
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| ___smoothTanX (stx) | double | 0.0 |
______The smoothTangent X component |
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| ___smoothTanY (sty) | double | 0.0 |
______The smoothTangent Y component |
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| ___smoothTanZ (stz) | double | 0.0 |
______The smoothTangent Z component |
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| outLinearTarget (lt) | double3 | n/a |
___The target for next linear tangent |
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| ___outLinearTargetX (ltx) | double | 0.0 |
______The linearTarget X component |
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| ___outLinearTargetY (lty) | double | 0.0 |
______The linearTarget Y component |
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| ___outLinearTargetZ (ltz) | double | 0.0 |
______The linearTarget Z component |
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| parentInverseMatrix (pim) | matrix | Identity |
___The parent inverse matrix from the object connected to the output |
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| inTangent (it) | matrix | Identity |
___The user defined floating tangent matrix |
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| previousVertex (pv) | matrix | Identity |
___The CV that is on the opposite side of the current vertex |
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| currentVertex (cv) | matrix | Identity |
___The CV that this tangent is connect to |
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| nextVertex (nv) | matrix | Identity |
___The CV that this tangent points towards |
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| inLinearTarget (nlt) | double3 | n/a |
___Connect the outLinearTarget from another TwistTangent node controlling the same bezier segment here |
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| ___inLinearTargetX (nltx) | double | 0.0 |
______The linearTarget X component |
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| ___inLinearTargetY (nlty) | double | 0.0 |
______The linearTarget Y component |
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| ___inLinearTargetZ (nltz) | double | 0.0 |
______The linearTarget Z component |
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| auto (a) | double | 1.0 |
___Whether or not the output is controlled automatically by the CVs |
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| smooth (s) | double | 1.0 |
___Whether an automatic output is smooth or linear |
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| weight (w) | double | 1.0 |
___The Length of the auto tangent. A weight of 1 is 1/3 of the distance between the current and next CVs |
A node that gets transformations at a given parameters along the spline. Generally, you will make many rider objects, and skin your geometry to those riders.
This node contains many convenience options. Normalization allows easy 0 to 1 parameterization no matter the length of the spline (as a spline that is unpinned will default to parameterizing by length). The globalOffset and globalSpread parameters are common sliding options. And useCycle allows you to constrain in loops so any rider that goes past the end parameter will loop back to the beginning, and vice-versa.
The multiple spline inputs allows you to switch between controlling splines. For instance, you could build a second spline with extra controls as the need arose, and swap control of the riders to that new spline.
ScaleCompensation exists because each input parameter would need a multipler attached to it to allow uniform scaling without changing behavior. This plug and the one on the spline handles all of that internally.
Note: Despite its name, this isn't actually implemented as a constraint, but it behaves similarly.
| Long Name (short name) | Type | Default |
|---|---|---|
| rotateOrder (ro) | enum | XYZ |
___Enum of the rotation order standard to Maya |
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| globalOffset (go) | double | 0.0 |
___A value added to all input parameters. This shifts everything connected to this constraint along the spline. |
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| globalSpread (gs) | double | 1.0 |
___A value multiplied by all input parameters. This spreads everything out (happens before the offset) |
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| scaleCompensation (sclcmp) | double | 1.0 |
___The overall scale of the spline. This is required to make riding/pinning/offsets work correctly |
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| useCycle (uc) | false | |
___Whether or not to cycle the parameters once they go past the end. If not, they extrapolate linearly. |
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| normalize (n) | boolen | True |
___If true, then the input parameters are remapped so that (0, normValue) maps to (0, restLength) of the spline |
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| normValue (nv) | double | 1.0 |
___The remapped maximum value when normalizing |
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| inputSplines (is) | compound | n/a |
___The group that is a spline and its corresponding weight. |
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| ___spline (s) | ||
______An input spline |
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| ___weight (w) | double | 1.0 |
______The constraint weight of that spline |
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| params (ps) | ||
___The parameters for the constraints, and their parent inverse matrices |
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| ___param (p) | double | 0.0 |
______The parameter where an object will stick to the spline. |
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| ___parentInverseMatrix (pim) | matrix | identity |
______The parentInverseMatrix of the object sticking to the spline |
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| outputs (out) | ||
| ___translate (t) | double3 | n/a |
______The output translation |
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| ______translateX (tx) | double | 0.0 |
_________The output translation X Component |
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| ______translateY (ty) | double | 0.0 |
_________The output translation Y Component |
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| ______translateZ (tz) | double | 0.0 |
_________The output translation Z Component |
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| ___rotate (rot) | double3 | n/a |
______The output rotation |
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| ______rotateX (rotx) | angle | 0.0 |
_________The output rotation X Component |
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| ______rotateY (roty) | angle | 0.0 |
_________The output rotation Y Component |
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| ______rotateZ (rotz) | angle | 0.0 |
_________The output rotation Z Component |
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| ___scale (scl) | double3 | n/a |
______The output scale |
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| ______scaleX (sclx) | double | 0.0 |
_________The output scale X Component |
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| ______scaleY (scly) | double | 0.0 |
_________The output scale Y Component |
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| ______scaleZ (sclz) | double | 0.0 |
_________The output scale Z Component |