VertexShader

Place every vertex yourself: a whole field of swaying grass comes from one short shader and no mesh at all.

The vertex stage of a Shader. There are no vertex buffers: each of VertexCount vertices, InstanceCount times over, is placed from gl_VertexID and gl_InstanceID, and you write gl_Position, with uViewProj and uModel given. Write glueAlbedo to colour it; uTime follows the playhead of the video you last played or scrubbed. In Rendered, a Traced Shader drawing Triangles has this stage captured into the path trace, so it casts shadows and bounces light.