This adds object motion blur vectors for EEVEE as well as better noise
reduction for it.
For TAA reprojection we just compute the motion vector on the fly based on
camera motion and depth buffer. This makes possible to store another motion
vector only for the blurring which is not useful for TAA history fetching.
Motion Data is saved per object & per geometry if using deformation blur.
We support deformation motion blur by saving previous VBO and modifying the
actual GPUBatch for the geometry to include theses VBOs.
We store Previous and Next frame motion in the same motion vector buffer
(RG for prev and BA for next). This makes non linear motion blur (like
rotating objects) less prone to outward/inward blur.
We also improve the motion blur post process to expand outside the objects
border. We use a tile base approach and the max size of the blur is set via
a new render setting.
We use a background reconstruction method that needs another setting
(Background Separation).
Sampling is done using a fixed 8 dithered samples per direction. The final
render samples will clear the noise like other stochastic effects.
One caveat is that hair particles are not yet supported. Support will
come in another patch.
Reviewed By: jbakker
Differential Revision: https://developer.blender.org/D7297
