// Pass 3 (remap alpha): vertex program. void main (float4 pObj : POSITION, out float4 pClip : POSITION, out float zLinear : TEXCOORD0, uniform float4x4 mvp, uniform float4x4 mv) { pClip = mul(mvp, pObj); // obj -> clip space zLinear = mul(mv, pObj).z; // z in eye space }