void GregoryQuadPatch::eval(float3 *P, float3 *dPdu, float3 *dPdv, float u, float v)
{
float3 bicubic[16];
float U = 1 - u;
float V = 1 - v;
/* 8 9 10 11
* 12 0\1 2/3 13
* 14 4/5 6\7 15
* 16 17 18 19
*/
bicubic[5] = (u*hull[1] + v*hull[0])/no_zero_div(u + v);
bicubic[6] = (U*hull[2] + v*hull[3])/no_zero_div(U + v);
bicubic[9] = (u*hull[5] + V*hull[4])/no_zero_div(u + V);
bicubic[10] = (U*hull[6] + V*hull[7])/no_zero_div(U + V);
// Map gregory control points to bezier control points.
bicubic[0] = hull[8];
bicubic[1] = hull[9];
bicubic[2] = hull[10];
bicubic[3] = hull[11];
bicubic[4] = hull[12];
bicubic[7] = hull[13];
bicubic[8] = hull[14];
bicubic[11] = hull[15];
bicubic[12] = hull[16];
bicubic[13] = hull[17];
bicubic[14] = hull[18];
bicubic[15] = hull[19];
decasteljau_bicubic(P, dPdu, dPdv, bicubic, u, v);
}
void BicubicTangentPatch::eval(float3 *P, float3 *dPdu, float3 *dPdv, float u, float v)
{
decasteljau_bicubic(P, NULL, NULL, hull, u, v);
if(dPdu) *dPdu = decasteljau_tangent(utan, u, v);
if(dPdv) *dPdv = decasteljau_tangent(vtan, v, u);
}
void BicubicPatch::eval(float3 *P, float3 *dPdu, float3 *dPdv, float3 *N, float u, float v)
{
if (N) {
float3 dPdu_, dPdv_;
decasteljau_bicubic(P, &dPdu_, &dPdv_, hull, u, v);
if (dPdu && dPdv) {
*dPdu = dPdu_;
*dPdv = dPdv_;
}
*N = normalize(cross(dPdu_, dPdv_));
}
else {
decasteljau_bicubic(P, dPdu, dPdv, hull, u, v);
}
}
void BicubicPatch::eval(float3 *P, float3 *dPdu, float3 *dPdv, float u, float v)
{
decasteljau_bicubic(P, dPdu, dPdv, hull, u, v);
}
