+ 1 - u;  // == mix(w, 1, T)
                    float uv = mix(u, v, T);

                    localcoord = (w < 0) ? /*cubic*/ abcd : /*conic*/ abc/uv;
                } else {
                    localcoord = (fixedVertexID == 0) ? p0.xy : p3.xy;
                }
            }
            float2 vertexpos = AFFINE_MATRIX * localcoord + TRANSLATE;