1 /*
2 * Mesa 3-D graphics library
3 * Version: 6.5.2
4 *
5 * Copyright (C) 1999-2006 Brian Paul All Rights Reserved.
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a
8 * copy of this software and associated documentation files (the "Software"),
9 * to deal in the Software without restriction, including without limitation
10 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
11 * and/or sell copies of the Software, and to permit persons to whom the
12 * Software is furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included
15 * in all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
18 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
21 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
22 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
23 *
24 * Authors:
25 * Keith Whitwell <keith@tungstengraphics.com>
26 */
27
28
29 #define CLIP_DOTPROD(K, A, B, C, D) X(K)*A + Y(K)*B + Z(K)*C + W(K)*D
30
31 #define POLY_CLIP( PLANE_BIT, A, B, C, D ) \
32 do { \
33 if (mask & PLANE_BIT) { \
34 GLuint idxPrev = inlist[0]; \
35 GLfloat dpPrev = CLIP_DOTPROD(idxPrev, A, B, C, D ); \
36 GLuint outcount = 0; \
37 GLuint i; \
38 \
39 inlist[n] = inlist[0]; /* prevent rotation of vertices */ \
40 for (i = 1; i <= n; i++) { \
41 GLuint idx = inlist[i]; \
42 GLfloat dp = CLIP_DOTPROD(idx, A, B, C, D ); \
43 \
44 if (!IS_NEGATIVE(dpPrev)) { \
45 outlist[outcount++] = idxPrev; \
46 } \
47 \
48 if (DIFFERENT_SIGNS(dp, dpPrev)) { \
49 if (IS_NEGATIVE(dp)) { \
50 /* Going out of bounds. Avoid division by zero as we \
51 * know dp != dpPrev from DIFFERENT_SIGNS, above. \
52 */ \
53 GLfloat t = dp / (dp - dpPrev); \
54 INTERP_4F( t, coord[newvert], coord[idx], coord[idxPrev]); \
55 interp( ctx, t, newvert, idx, idxPrev, GL_TRUE ); \
56 } else { \
57 /* Coming back in. \
58 */ \
59 GLfloat t = dpPrev / (dpPrev - dp); \
60 INTERP_4F( t, coord[newvert], coord[idxPrev], coord[idx]); \
61 interp( ctx, t, newvert, idxPrev, idx, GL_FALSE ); \
62 } \
63 outlist[outcount++] = newvert++; \
64 } \
65 \
66 idxPrev = idx; \
67 dpPrev = dp; \
68 } \
69 \
70 if (outcount < 3) \
71 return; \
72 \
73 { \
74 GLuint *tmp = inlist; \
75 inlist = outlist; \
76 outlist = tmp; \
77 n = outcount; \
78 } \
79 } \
80 } while (0)
81
82
83 #define LINE_CLIP(PLANE_BIT, A, B, C, D ) \
84 do { \
85 if (mask & PLANE_BIT) { \
86 const GLfloat dp0 = CLIP_DOTPROD( v0, A, B, C, D ); \
87 const GLfloat dp1 = CLIP_DOTPROD( v1, A, B, C, D ); \
88 const GLboolean neg_dp0 = IS_NEGATIVE(dp0); \
89 const GLboolean neg_dp1 = IS_NEGATIVE(dp1); \
90 \
91 /* For regular clipping, we know from the clipmask that one \
92 * (or both) of these must be negative (otherwise we wouldn't \
93 * be here). \
94 * For userclip, there is only a single bit for all active \
95 * planes, so we can end up here when there is nothing to do, \
96 * hence the second IS_NEGATIVE() test: \
97 */ \
98 if (neg_dp0 && neg_dp1) \
99 return; /* both vertices outside clip plane: discard */ \
100 \
101 if (neg_dp1) { \
102 GLfloat t = dp1 / (dp1 - dp0); \
103 if (t > t1) t1 = t; \
104 } else if (neg_dp0) { \
105 GLfloat t = dp0 / (dp0 - dp1); \
106 if (t > t0) t0 = t; \
107 } \
108 if (t0 + t1 >= 1.0) \
109 return; /* discard */ \
110 } \
111 } while (0)
112
113
114
115 /* Clip a line against the viewport and user clip planes.
116 */
117 static inline void
TAG(clip_line)118 TAG(clip_line)( struct gl_context *ctx, GLuint v0, GLuint v1, GLubyte mask )
119 {
120 TNLcontext *tnl = TNL_CONTEXT(ctx);
121 struct vertex_buffer *VB = &tnl->vb;
122 tnl_interp_func interp = tnl->Driver.Render.Interp;
123 GLfloat (*coord)[4] = VB->ClipPtr->data;
124 GLuint newvert = VB->Count;
125 GLfloat t0 = 0;
126 GLfloat t1 = 0;
127 GLuint p;
128 const GLuint v0_orig = v0;
129
130 if (mask & CLIP_FRUSTUM_BITS) {
131 LINE_CLIP( CLIP_RIGHT_BIT, -1, 0, 0, 1 );
132 LINE_CLIP( CLIP_LEFT_BIT, 1, 0, 0, 1 );
133 LINE_CLIP( CLIP_TOP_BIT, 0, -1, 0, 1 );
134 LINE_CLIP( CLIP_BOTTOM_BIT, 0, 1, 0, 1 );
135 LINE_CLIP( CLIP_FAR_BIT, 0, 0, -1, 1 );
136 LINE_CLIP( CLIP_NEAR_BIT, 0, 0, 1, 1 );
137 }
138
139 if (mask & CLIP_USER_BIT) {
140 for (p = 0; p < ctx->Const.MaxClipPlanes; p++) {
141 if (ctx->Transform.ClipPlanesEnabled & (1 << p)) {
142 const GLfloat a = ctx->Transform._ClipUserPlane[p][0];
143 const GLfloat b = ctx->Transform._ClipUserPlane[p][1];
144 const GLfloat c = ctx->Transform._ClipUserPlane[p][2];
145 const GLfloat d = ctx->Transform._ClipUserPlane[p][3];
146 LINE_CLIP( CLIP_USER_BIT, a, b, c, d );
147 }
148 }
149 }
150
151 if (VB->ClipMask[v0]) {
152 INTERP_4F( t0, coord[newvert], coord[v0], coord[v1] );
153 interp( ctx, t0, newvert, v0, v1, GL_FALSE );
154 v0 = newvert;
155 newvert++;
156 }
157 else {
158 ASSERT(t0 == 0.0);
159 }
160
161 /* Note: we need to use vertex v0_orig when computing the new
162 * interpolated/clipped vertex position, not the current v0 which
163 * may have got set when we clipped the other end of the line!
164 */
165 if (VB->ClipMask[v1]) {
166 INTERP_4F( t1, coord[newvert], coord[v1], coord[v0_orig] );
167 interp( ctx, t1, newvert, v1, v0_orig, GL_FALSE );
168
169 if (ctx->Light.ShadeModel == GL_FLAT)
170 tnl->Driver.Render.CopyPV( ctx, newvert, v1 );
171
172 v1 = newvert;
173
174 newvert++;
175 }
176 else {
177 ASSERT(t1 == 0.0);
178 }
179
180 tnl->Driver.Render.ClippedLine( ctx, v0, v1 );
181 }
182
183
184 /* Clip a triangle against the viewport and user clip planes.
185 */
186 static inline void
TAG(clip_tri)187 TAG(clip_tri)( struct gl_context *ctx, GLuint v0, GLuint v1, GLuint v2, GLubyte mask )
188 {
189 TNLcontext *tnl = TNL_CONTEXT(ctx);
190 struct vertex_buffer *VB = &tnl->vb;
191 tnl_interp_func interp = tnl->Driver.Render.Interp;
192 GLuint newvert = VB->Count;
193 GLfloat (*coord)[4] = VB->ClipPtr->data;
194 GLuint pv = v2;
195 GLuint vlist[2][MAX_CLIPPED_VERTICES];
196 GLuint *inlist = vlist[0], *outlist = vlist[1];
197 GLuint p;
198 GLuint n = 3;
199
200 ASSIGN_3V(inlist, v2, v0, v1 ); /* pv rotated to slot zero */
201
202 if (0) {
203 /* print pre-clip vertex coords */
204 GLuint i, j;
205 printf("pre clip:\n");
206 for (i = 0; i < n; i++) {
207 j = inlist[i];
208 printf(" %u: %u: %f, %f, %f, %f\n",
209 i, j,
210 coord[j][0], coord[j][1], coord[j][2], coord[j][3]);
211 assert(!IS_INF_OR_NAN(coord[j][0]));
212 assert(!IS_INF_OR_NAN(coord[j][1]));
213 assert(!IS_INF_OR_NAN(coord[j][2]));
214 assert(!IS_INF_OR_NAN(coord[j][3]));
215 }
216 }
217
218
219 if (mask & CLIP_FRUSTUM_BITS) {
220 POLY_CLIP( CLIP_RIGHT_BIT, -1, 0, 0, 1 );
221 POLY_CLIP( CLIP_LEFT_BIT, 1, 0, 0, 1 );
222 POLY_CLIP( CLIP_TOP_BIT, 0, -1, 0, 1 );
223 POLY_CLIP( CLIP_BOTTOM_BIT, 0, 1, 0, 1 );
224 POLY_CLIP( CLIP_FAR_BIT, 0, 0, -1, 1 );
225 POLY_CLIP( CLIP_NEAR_BIT, 0, 0, 1, 1 );
226 }
227
228 if (mask & CLIP_USER_BIT) {
229 for (p = 0; p < ctx->Const.MaxClipPlanes; p++) {
230 if (ctx->Transform.ClipPlanesEnabled & (1 << p)) {
231 const GLfloat a = ctx->Transform._ClipUserPlane[p][0];
232 const GLfloat b = ctx->Transform._ClipUserPlane[p][1];
233 const GLfloat c = ctx->Transform._ClipUserPlane[p][2];
234 const GLfloat d = ctx->Transform._ClipUserPlane[p][3];
235 POLY_CLIP( CLIP_USER_BIT, a, b, c, d );
236 }
237 }
238 }
239
240 if (ctx->Light.ShadeModel == GL_FLAT) {
241 if (pv != inlist[0]) {
242 ASSERT( inlist[0] >= VB->Count );
243 tnl->Driver.Render.CopyPV( ctx, inlist[0], pv );
244 }
245 }
246
247 if (0) {
248 /* print post-clip vertex coords */
249 GLuint i, j;
250 printf("post clip:\n");
251 for (i = 0; i < n; i++) {
252 j = inlist[i];
253 printf(" %u: %u: %f, %f, %f, %f\n",
254 i, j,
255 coord[j][0], coord[j][1], coord[j][2], coord[j][3]);
256 }
257 }
258
259 tnl->Driver.Render.ClippedPolygon( ctx, inlist, n );
260 }
261
262
263 /* Clip a quad against the viewport and user clip planes.
264 */
265 static inline void
TAG(clip_quad)266 TAG(clip_quad)( struct gl_context *ctx, GLuint v0, GLuint v1, GLuint v2, GLuint v3,
267 GLubyte mask )
268 {
269 TNLcontext *tnl = TNL_CONTEXT(ctx);
270 struct vertex_buffer *VB = &tnl->vb;
271 tnl_interp_func interp = tnl->Driver.Render.Interp;
272 GLuint newvert = VB->Count;
273 GLfloat (*coord)[4] = VB->ClipPtr->data;
274 GLuint pv = v3;
275 GLuint vlist[2][MAX_CLIPPED_VERTICES];
276 GLuint *inlist = vlist[0], *outlist = vlist[1];
277 GLuint p;
278 GLuint n = 4;
279
280 ASSIGN_4V(inlist, v3, v0, v1, v2 ); /* pv rotated to slot zero */
281
282 if (mask & CLIP_FRUSTUM_BITS) {
283 POLY_CLIP( CLIP_RIGHT_BIT, -1, 0, 0, 1 );
284 POLY_CLIP( CLIP_LEFT_BIT, 1, 0, 0, 1 );
285 POLY_CLIP( CLIP_TOP_BIT, 0, -1, 0, 1 );
286 POLY_CLIP( CLIP_BOTTOM_BIT, 0, 1, 0, 1 );
287 POLY_CLIP( CLIP_FAR_BIT, 0, 0, -1, 1 );
288 POLY_CLIP( CLIP_NEAR_BIT, 0, 0, 1, 1 );
289 }
290
291 if (mask & CLIP_USER_BIT) {
292 for (p = 0; p < ctx->Const.MaxClipPlanes; p++) {
293 if (ctx->Transform.ClipPlanesEnabled & (1 << p)) {
294 const GLfloat a = ctx->Transform._ClipUserPlane[p][0];
295 const GLfloat b = ctx->Transform._ClipUserPlane[p][1];
296 const GLfloat c = ctx->Transform._ClipUserPlane[p][2];
297 const GLfloat d = ctx->Transform._ClipUserPlane[p][3];
298 POLY_CLIP( CLIP_USER_BIT, a, b, c, d );
299 }
300 }
301 }
302
303 if (ctx->Light.ShadeModel == GL_FLAT) {
304 if (pv != inlist[0]) {
305 ASSERT( inlist[0] >= VB->Count );
306 tnl->Driver.Render.CopyPV( ctx, inlist[0], pv );
307 }
308 }
309
310 tnl->Driver.Render.ClippedPolygon( ctx, inlist, n );
311 }
312
313 #undef W
314 #undef Z
315 #undef Y
316 #undef X
317 #undef SIZE
318 #undef TAG
319 #undef POLY_CLIP
320 #undef LINE_CLIP
321