So, I was trying to just do a simple fake shadow on the ground in mixed reality using a grayscale texture. In the editor, I can use an Unlit shader with transparency set to Multiply, but then I get a warning: [Worker2] Unsupported alpha mode: Multiply. And in the simulator, I just get the grayscale texture with no transparency.
Is this going to be supported in the future? And is there a workaround for doing fake shadows on the ground?
Unfortunately, we have no control over this. The underlying RealityKit materials (UnlitMaterial or ShaderGraphMaterial) don’t support a multiply blend mode. I would suggest providing feedback to Apple requesting this functionality.
Currently, the only shadow support is through the PolySpatial Grounding Shadow component, which provides a top-down shadow (a proxy for GroundingShadowComponent). Note that it requires Lit shaders on both casters and receivers to work. Eventually, we also plan to add shadow support to the PolySpatial Lighting shader graph node.
Thanks for the reply!
I ended up fixing this by simply making my shadow texture on a transparent background so I could use the normal alpha blend mode instead of multiply. That works perfectly fine.
For some reason, I couldn’t get the result I wanted with the PolySpatial Grounding Shadow – it wasn’t strong enough and there are no controls to make any changes to the output.