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/*
* Copyright 2011-2013 Blender Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* Parts adapted from code in the public domain in NVidia Mesh Tools. */
#include "mesh.h"
#include "subd_patch.h"
#include "util_math.h"
#include "util_types.h"
CCL_NAMESPACE_BEGIN
/* De Casteljau Evaluation */
static void decasteljau_cubic(float3 *P, float3 *dt, float t, const float3 cp[4])
{
float3 d0 = cp[0] + t*(cp[1] - cp[0]);
float3 d1 = cp[1] + t*(cp[2] - cp[1]);
float3 d2 = cp[2] + t*(cp[3] - cp[2]);
d0 += t*(d1 - d0);
d1 += t*(d2 - d1);
*P = d0 + t*(d1 - d0);
if(dt) *dt = d1 - d0;
}
static void decasteljau_bicubic(float3 *P, float3 *du, float3 *dv, const float3 cp[16], float u, float v)
{
float3 ucp[4], utn[4];
/* interpolate over u */
decasteljau_cubic(ucp+0, utn+0, u, cp);
decasteljau_cubic(ucp+1, utn+1, u, cp+4);
decasteljau_cubic(ucp+2, utn+2, u, cp+8);
decasteljau_cubic(ucp+3, utn+3, u, cp+12);
/* interpolate over v */
decasteljau_cubic(P, dv, v, ucp);
if(du) decasteljau_cubic(du, NULL, v, utn);
}
/* Linear Quad Patch */
void LinearQuadPatch::eval(float3 *P, float3 *dPdu, float3 *dPdv, float3 *N, float u, float v)
{
float3 d0 = interp(hull[0], hull[1], u);
float3 d1 = interp(hull[2], hull[3], u);
*P = interp(d0, d1, v);
if(dPdu && dPdv) {
*dPdu = interp(hull[1] - hull[0], hull[3] - hull[2], v);
*dPdv = interp(hull[2] - hull[0], hull[3] - hull[1], u);
}
if(N) {
*N = normalize(interp(interp(normals[0], normals[1], u), interp(normals[2], normals[3], u), v));
}
}
BoundBox LinearQuadPatch::bound()
{
BoundBox bbox = BoundBox::empty;
for(int i = 0; i < 4; i++)
bbox.grow(hull[i]);
return bbox;
}
/* Bicubic Patch */
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);
}
}
BoundBox BicubicPatch::bound()
{
BoundBox bbox = BoundBox::empty;
for(int i = 0; i < 16; i++)
bbox.grow(hull[i]);
return bbox;
}
CCL_NAMESPACE_END
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