1 /*
2 Copyright (c) 2005-2020 Intel Corporation
3
4 Licensed under the Apache License, Version 2.0 (the "License");
5 you may not use this file except in compliance with the License.
6 You may obtain a copy of the License at
7
8 http://www.apache.org/licenses/LICENSE-2.0
9
10 Unless required by applicable law or agreed to in writing, software
11 distributed under the License is distributed on an "AS IS" BASIS,
12 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 See the License for the specific language governing permissions and
14 limitations under the License.
15 */
16
17 /*
18 The original source for this example is
19 Copyright (c) 1994-2008 John E. Stone
20 All rights reserved.
21
22 Redistribution and use in source and binary forms, with or without
23 modification, are permitted provided that the following conditions
24 are met:
25 1. Redistributions of source code must retain the above copyright
26 notice, this list of conditions and the following disclaimer.
27 2. Redistributions in binary form must reproduce the above copyright
28 notice, this list of conditions and the following disclaimer in the
29 documentation and/or other materials provided with the distribution.
30 3. The name of the author may not be used to endorse or promote products
31 derived from this software without specific prior written permission.
32
33 THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
34 OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
35 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
36 ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
37 DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
38 DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
39 OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
40 HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
41 LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
42 OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
43 SUCH DAMAGE.
44 */
45
46 /*
47 * triangle.cpp - This file contains the functions for dealing with triangles.
48 */
49
50 #include "machine.h"
51 #include "types.h"
52 #include "vector.h"
53 #include "macros.h"
54 #include "intersect.h"
55 #include "util.h"
56
57 #define TRIANGLE_PRIVATE
58 #include "triangle.h"
59
60 static object_methods tri_methods = {
61 (void (*)(void *, void *))(tri_intersect),
62 (void (*)(void *, void *, void *, void *))(tri_normal),
63 tri_bbox,
64 free
65 };
66
67 static object_methods stri_methods = {
68 (void (*)(void *, void *))(tri_intersect),
69 (void (*)(void *, void *, void *, void *))(stri_normal),
70 tri_bbox,
71 free
72 };
73
newtri(void * tex,vector v0,vector v1,vector v2)74 object * newtri(void * tex, vector v0, vector v1, vector v2) {
75 tri * t;
76 vector edge1, edge2, edge3;
77
78 VSub(&v1, &v0, &edge1);
79 VSub(&v2, &v0, &edge2);
80 VSub(&v2, &v1, &edge3);
81
82 /* check to see if this will be a degenerate triangle before creation */
83 if ((VLength(&edge1) >= EPSILON) &&
84 (VLength(&edge2) >= EPSILON) &&
85 (VLength(&edge3) >= EPSILON)) {
86
87 t=(tri *) rt_getmem(sizeof(tri));
88
89 t->nextobj = NULL;
90 t->methods = &tri_methods;
91
92 t->tex = (texture *)tex;
93 t->v0 = v0;
94 t->edge1 = edge1;
95 t->edge2 = edge2;
96
97 return (object *) t;
98 }
99
100 return NULL; /* was a degenerate triangle */
101 }
102
103
newstri(void * tex,vector v0,vector v1,vector v2,vector n0,vector n1,vector n2)104 object * newstri(void * tex, vector v0, vector v1, vector v2,
105 vector n0, vector n1, vector n2) {
106 stri * t;
107 vector edge1, edge2, edge3;
108
109 VSub(&v1, &v0, &edge1);
110 VSub(&v2, &v0, &edge2);
111 VSub(&v2, &v1, &edge3);
112
113 /* check to see if this will be a degenerate triangle before creation */
114 if ((VLength(&edge1) >= EPSILON) &&
115 (VLength(&edge2) >= EPSILON) &&
116 (VLength(&edge3) >= EPSILON)) {
117
118 t=(stri *) rt_getmem(sizeof(stri));
119
120 t->nextobj = NULL;
121 t->methods = &stri_methods;
122
123 t->tex = (texture *)tex;
124 t->v0 = v0;
125 t->edge1 = edge1;
126 t->edge2 = edge2;
127 t->n0 = n0;
128 t->n1 = n1;
129 t->n2 = n2;
130
131 return (object *) t;
132 }
133
134 return NULL; /* was a degenerate triangle */
135 }
136
137 #define CROSS(dest,v1,v2) \
138 dest.x=v1.y*v2.z-v1.z*v2.y; \
139 dest.y=v1.z*v2.x-v1.x*v2.z; \
140 dest.z=v1.x*v2.y-v1.y*v2.x;
141
142 #define DOT(v1,v2) (v1.x*v2.x+v1.y*v2.y+v1.z*v2.z)
143
144 #define SUB(dest,v1,v2) \
145 dest.x=v1.x-v2.x; \
146 dest.y=v1.y-v2.y; \
147 dest.z=v1.z-v2.z;
148
tri_bbox(void * obj,vector * min,vector * max)149 static int tri_bbox(void * obj, vector * min, vector * max) {
150 tri * t = (tri *) obj;
151 vector v1, v2;
152
153 VAdd(&t->v0, &t->edge1, &v1);
154 VAdd(&t->v0, &t->edge2, &v2);
155
156 min->x = MYMIN( t->v0.x , MYMIN( v1.x , v2.x ));
157 min->y = MYMIN( t->v0.y , MYMIN( v1.y , v2.y ));
158 min->z = MYMIN( t->v0.z , MYMIN( v1.z , v2.z ));
159
160 max->x = MYMAX( t->v0.x , MYMAX( v1.x , v2.x ));
161 max->y = MYMAX( t->v0.y , MYMAX( v1.y , v2.y ));
162 max->z = MYMAX( t->v0.z , MYMAX( v1.z , v2.z ));
163
164 return 1;
165 }
166
tri_intersect(tri * trn,ray * ry)167 static void tri_intersect(tri * trn, ray * ry) {
168 vector tvec, pvec, qvec;
169 flt det, inv_det, t, u, v;
170
171 /* begin calculating determinant - also used to calculate U parameter */
172 CROSS(pvec, ry->d, trn->edge2);
173
174 /* if determinant is near zero, ray lies in plane of triangle */
175 det = DOT(trn->edge1, pvec);
176
177 if (det > -EPSILON && det < EPSILON)
178 return;
179
180 inv_det = 1.0 / det;
181
182 /* calculate distance from vert0 to ray origin */
183 SUB(tvec, ry->o, trn->v0);
184
185 /* calculate U parameter and test bounds */
186 u = DOT(tvec, pvec) * inv_det;
187 if (u < 0.0 || u > 1.0)
188 return;
189
190 /* prepare to test V parameter */
191 CROSS(qvec, tvec, trn->edge1);
192
193 /* calculate V parameter and test bounds */
194 v = DOT(ry->d, qvec) * inv_det;
195 if (v < 0.0 || u + v > 1.0)
196 return;
197
198 /* calculate t, ray intersects triangle */
199 t = DOT(trn->edge2, qvec) * inv_det;
200
201 add_intersection(t,(object *) trn, ry);
202 }
203
204
tri_normal(tri * trn,vector * pnt,ray * incident,vector * N)205 static void tri_normal(tri * trn, vector * pnt, ray * incident, vector * N) {
206
207 CROSS((*N), trn->edge1, trn->edge2);
208
209 VNorm(N);
210
211 if (VDot(N, &(incident->d)) > 0.0) {
212 N->x=-N->x;
213 N->y=-N->y;
214 N->z=-N->z;
215 }
216 }
217
stri_normal(stri * trn,vector * pnt,ray * incident,vector * N)218 static void stri_normal(stri * trn, vector * pnt, ray * incident, vector * N) {
219 flt U, V, W, lensqr;
220 vector P, tmp, norm;
221
222 CROSS(norm, trn->edge1, trn->edge2);
223 lensqr = DOT(norm, norm);
224
225 VSUB((*pnt), trn->v0, P);
226
227 CROSS(tmp, P, trn->edge2);
228 U = DOT(tmp, norm) / lensqr;
229
230 CROSS(tmp, trn->edge1, P);
231 V = DOT(tmp, norm) / lensqr;
232
233 W = 1.0 - (U + V);
234
235 N->x = W*trn->n0.x + U*trn->n1.x + V*trn->n2.x;
236 N->y = W*trn->n0.y + U*trn->n1.y + V*trn->n2.y;
237 N->z = W*trn->n0.z + U*trn->n1.z + V*trn->n2.z;
238
239 VNorm(N);
240 }
241
242