forked from bartvdbraak/blender
c1a27a76cf
This way we prevent cracks in the model due to discontinuous normals, by using smooth normals for displacement instead of always getting flat normals after linear subdivision. Reviewed By: brecht Differential Revision: https://developer.blender.org/D1916
145 lines
3.1 KiB
C++
145 lines
3.1 KiB
C++
/*
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* Copyright 2011-2013 Blender Foundation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/* Parts adapted from code in the public domain in NVidia Mesh Tools. */
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#include "mesh.h"
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#include "subd_patch.h"
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#include "util_math.h"
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#include "util_types.h"
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CCL_NAMESPACE_BEGIN
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/* De Casteljau Evaluation */
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static void decasteljau_cubic(float3 *P, float3 *dt, float t, const float3 cp[4])
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{
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float3 d0 = cp[0] + t*(cp[1] - cp[0]);
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float3 d1 = cp[1] + t*(cp[2] - cp[1]);
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float3 d2 = cp[2] + t*(cp[3] - cp[2]);
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d0 += t*(d1 - d0);
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d1 += t*(d2 - d1);
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*P = d0 + t*(d1 - d0);
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if(dt) *dt = d1 - d0;
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}
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static void decasteljau_bicubic(float3 *P, float3 *du, float3 *dv, const float3 cp[16], float u, float v)
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{
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float3 ucp[4], utn[4];
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/* interpolate over u */
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decasteljau_cubic(ucp+0, utn+0, u, cp);
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decasteljau_cubic(ucp+1, utn+1, u, cp+4);
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decasteljau_cubic(ucp+2, utn+2, u, cp+8);
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decasteljau_cubic(ucp+3, utn+3, u, cp+12);
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/* interpolate over v */
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decasteljau_cubic(P, dv, v, ucp);
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if(du) decasteljau_cubic(du, NULL, v, utn);
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}
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/* Linear Quad Patch */
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void LinearQuadPatch::eval(float3 *P, float3 *dPdu, float3 *dPdv, float3 *N, float u, float v)
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{
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float3 d0 = interp(hull[0], hull[1], u);
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float3 d1 = interp(hull[2], hull[3], u);
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*P = interp(d0, d1, v);
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if(dPdu && dPdv) {
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*dPdu = interp(hull[1] - hull[0], hull[3] - hull[2], v);
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*dPdv = interp(hull[2] - hull[0], hull[3] - hull[1], u);
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}
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if(N) {
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*N = normalize(interp(interp(normals[0], normals[1], u), interp(normals[2], normals[3], u), v));
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}
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}
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BoundBox LinearQuadPatch::bound()
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{
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BoundBox bbox = BoundBox::empty;
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for(int i = 0; i < 4; i++)
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bbox.grow(hull[i]);
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return bbox;
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}
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/* Linear Triangle Patch */
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void LinearTrianglePatch::eval(float3 *P, float3 *dPdu, float3 *dPdv, float3 *N, float u, float v)
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{
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*P = u*hull[0] + v*hull[1] + (1.0f - u - v)*hull[2];
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if(dPdu && dPdv) {
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*dPdu = hull[0] - hull[2];
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*dPdv = hull[1] - hull[2];
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}
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if(N) {
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*N = normalize(u*normals[0] + v*normals[1] + (1.0f - u - v)*normals[2]);
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}
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}
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BoundBox LinearTrianglePatch::bound()
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{
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BoundBox bbox = BoundBox::empty;
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for(int i = 0; i < 3; i++)
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bbox.grow(hull[i]);
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return bbox;
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}
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/* Bicubic Patch */
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void BicubicPatch::eval(float3 *P, float3 *dPdu, float3 *dPdv, float3 *N, float u, float v)
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{
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if (N) {
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float3 dPdu_, dPdv_;
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decasteljau_bicubic(P, &dPdu_, &dPdv_, hull, u, v);
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if (dPdu && dPdv) {
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*dPdu = dPdu_;
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*dPdv = dPdv_;
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}
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*N = normalize(cross(dPdu_, dPdv_));
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}
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else {
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decasteljau_bicubic(P, dPdu, dPdv, hull, u, v);
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}
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}
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BoundBox BicubicPatch::bound()
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{
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BoundBox bbox = BoundBox::empty;
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for(int i = 0; i < 16; i++)
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bbox.grow(hull[i]);
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return bbox;
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}
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CCL_NAMESPACE_END
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