Question by OscarLouw · Sep 04, 2020 at 10:12 AM · shader shaders shadows clipping vertex shader

Shadows on alpha clipping/vertex offset shaders misaligned when using screen space texture

Hi all!

I am rendering two meshes (via a command buffer) to a RenderTexture, which I am using in several shaders to move vertices or do transparent cutouts on objects. Everything is great.

The problem happens in the shadow pass. Since I am comparing the object's vertex position with a screen space texture, the shadows are being drawn wrong. This is, I assume, because the shadow texture is generated from a orthographic camera at a different angle.

Some pictures to demonstrate:

Image of the RenderTexture followed by the color buffer followed by the shadow pass followed by the nodes in Amplify Shader Editor

The screen position node essentially takes the vertex position, multiplies it by the ObjectToClipPos matrix, and divides by the W component. Masking the XY component gives us the

Should I be sending the renderTexture's camera's viewProjectMatrix to a shader global and use that in some way to offset the viewport texture based on the camera that is currently rendering?

Any thoughts would be greatly appreciated!

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