StageBuiltIn

Not a built-in: an ordinary located input.

This invocation's position in the whole dispatch — the workgroup index times the workgroup size, plus the position within the group. The one nearly every compute shader wants.

Which workgroup this invocation is in.

This invocation's position within its own workgroup.

This invocation's position within its workgroup, flattened to a single index — the scalar form of GroupThreadId, and what indexes shared storage.

Which vertex is being shaded, counting from the draw's first index.

Which instance is being drawn, counting from the draw's first instance.

Where this fragment is on the render target, in pixels, with the depth and 1/w behind it.

Whether the triangle this fragment came from faces the viewer.