Previously fluid simulation and Alembic modifiers had a dedicated function to query the velocity for motion blur. Now use a more generic system where those modifiers output a velocity attribute. Advantages: * Geometry and particle nodes can output velocity through the same mechanism, or read the attribute coming from earlier modifiers. * The velocity can be preserved through modifiers like subdivision surface or auto smooth. * USD and Alembic previously only output velocity from fluid simulation, now they work with velocity from other sources too. * Simplifies the code for renderers like Cycles and exporters like Alembic and USD. This breaks compatibility: * External renderers and exporters accessing these velocities through the Python API now need to use the attribute instead. * Existing modifier node setups that create an attribute named "velocity" will render differently with motion blur. Differential Revision: https://developer.blender.org/D12305
11 KiB
11 KiB