Implement reflective surfaces.

Reflective surfaces (planes) use a custom shader to blend their
texture with a texture that contains the reflected image. The
reflected image is rendered to a texture as a separate render
pass in the SceneView.

Because reflective textures are generated after the preparation
phase, additional functions are needed to reapply the texture
to the drawable.

PiperOrigin-RevId: 889213413
Change-Id: I7bad39d62e3e5ba38cf6ac667fec5b87bfa7b2a2

src/experimental/filament/CMakeLists.txt

@@ -43,6 +43,7 @@ target_sources(${MUJOCO_FILAMENT_TARGET_NAME}
         filament/light.h
         filament/material.cc
         filament/material.h
+        filament/math_util.cc
         filament/math_util.h
         filament/model_util.cc
         filament/model_util.h