maya-weighted-blend-matrix

Maya weighted blend matrix node that will allow blending of the transformation components separately. Rather than an additive approach like Maya's build in blendMatrix node its behaviour is more similar to a normal constraint where the translate, scale and shear components are blended using linear interpolation and the rotation is solved using average quaternions. Each component can be blended using separated weighting making this node a good candidate for space switch as it doesn't require separate constraints for different components.

Installation

• Extract the content of the .rar file anywhere on disk.
• Build the plugin for a specific Maya version.
• Drag the weighted-blend-matrix.mel file in Maya to permanently install the script.

Compiling

Building the plugin using cmake will place the plugin in the plug-ins folder with a maya version divider. This will ensure the plug-in is compatible with the launched version of Maya.

1. Copy the following libraries to their respective folders in /extern:

   • Eigen 3.3.9 with path /extern/Eigen/Eigen/Dense,

2. Open Terminal

cd <PATH_TO_MODULE>
mkdir build/<MAYA_VERSION>
cd build/<MAYA_VERSION>
cmake -A x64 -T v141 -DMAYA_VERSION=<MAYA_VERSION> ../../
cmake --build . --target install --config Release

Usage

Once the plug-in is build and loaded a new wtBlendMatrix node can be created. There is a compound array attribute that contains blendInputMatrix, blendOffsetMatrix, blendTranslateWeight, blendRotateWeight, blendScaleWeight and blendShearWeight attributes. By default the weight values are set to 1. The blendInputMatrix can be driven directly by a nodes world matrix attribute and blendOffsetMatrix can be calculated and set by the user to get the matrix in the desired location.

At the top level the node has a restMatrix which is used when the sum of weights on a component is 0. The offsetMatrix can be used as an offset matrix that is used in the calculation after the blend matrix itself has been calculated, as a matrix attribute is not keyable a composeMatrix node can be used to preserve the output location if using the node as a space switch.

When using Maya 2020 or above the decomposeMatrix and composeMatrix nodes can be omitted as the outputMatrix attribute can be plugged directly into the offsetParentMatrix which leaves the translate/rotate/scale and shear attributes free to key the offset.