fn append_user_texsize_constants(out: &mut String, plan: &TextureBindingPlan)Expand description
Emit a let texsize_<NAME>: vec4<f32> = vec4<f32>(w, h, 1/w, 1/h); line
for each filled slot in the plan. Preset code reads these directly:
tex2D(sampler_clouds, uv + texsize_clouds.zw * dt) is a common pattern
for “step one texel along the texture dimension”.