Linearly interpolating between two matrixes

[MarcGuiselin]

Animating transforms requires computing intermediary states at arbitrary intervals between two transforms.

I propose the addition of a interpolate(from, to, progress)

[MarcGuiselin]

There are several ways to linearly interpolate between two transformation matrixes. However, in order to match the behavior of browsers (and produce no weird deformations), the matrix must be decomposed into scale, skew, translation, perspective and quaternion rotation. This is called polar decomposition. Then we can linearly interpolate between those and compose a new matrix... no small feat.

See:

• StackOverflow thread
• "Matrix Animation and Polar Decomposition" by Shoemake and Duff
• WebKit TransformationMatrix interpolation source

[jlmakes]

This sounds freaking awesome @MarcGuiselin, I appreciate the feature request and resources.