1 /*
2 * Mesa 3-D graphics library
3 *
4 * Copyright (C) 1999-2006 Brian Paul All Rights Reserved.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the "Software"),
8 * to deal in the Software without restriction, including without limitation
9 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
10 * and/or sell copies of the Software, and to permit persons to whom the
11 * Software is furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included
14 * in all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
17 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
20 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
21 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
22 * OTHER DEALINGS IN THE SOFTWARE.
23 *
24 * Authors:
25 * Keith Whitwell <keithw@vmware.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 (dpPrev >= 0.0f) { \
45 outlist[outcount++] = idxPrev; \
46 } \
47 \
48 if (DIFFERENT_SIGNS(dp, dpPrev)) { \
49 if (dp < 0.0f) { \
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 = dp0 < 0.0f; \
89 const GLboolean neg_dp1 = dp1 < 0.0f; \
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 < 0.0f 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 const GLuint v0_orig = v0;
128
129 if (mask & CLIP_FRUSTUM_BITS) {
130 LINE_CLIP( CLIP_RIGHT_BIT, -1, 0, 0, 1 );
131 LINE_CLIP( CLIP_LEFT_BIT, 1, 0, 0, 1 );
132 LINE_CLIP( CLIP_TOP_BIT, 0, -1, 0, 1 );
133 LINE_CLIP( CLIP_BOTTOM_BIT, 0, 1, 0, 1 );
134 LINE_CLIP( CLIP_FAR_BIT, 0, 0, -1, 1 );
135 LINE_CLIP( CLIP_NEAR_BIT, 0, 0, 1, 1 );
136 }
137
138 if (mask & CLIP_USER_BIT) {
139 GLbitfield enabled = ctx->Transform.ClipPlanesEnabled;
140 while (enabled) {
141 const int p = u_bit_scan(&enabled);
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 if (VB->ClipMask[v0]) {
151 INTERP_4F( t0, coord[newvert], coord[v0], coord[v1] );
152 interp( ctx, t0, newvert, v0, v1, GL_FALSE );
153 v0 = newvert;
154 newvert++;
155 }
156 else {
157 assert(t0 == 0.0);
158 }
159
160 /* Note: we need to use vertex v0_orig when computing the new
161 * interpolated/clipped vertex position, not the current v0 which
162 * may have got set when we clipped the other end of the line!
163 */
164 if (VB->ClipMask[v1]) {
165 INTERP_4F( t1, coord[newvert], coord[v1], coord[v0_orig] );
166 interp( ctx, t1, newvert, v1, v0_orig, GL_FALSE );
167
168 if (ctx->Light.ShadeModel == GL_FLAT)
169 tnl->Driver.Render.CopyPV( ctx, newvert, v1 );
170
171 v1 = newvert;
172
173 newvert++;
174 }
175 else {
176 assert(t1 == 0.0);
177 }
178
179 tnl->Driver.Render.ClippedLine( ctx, v0, v1 );
180 }
181
182
183 /* Clip a triangle against the viewport and user clip planes.
184 */
185 static inline void
TAG(clip_tri)186 TAG(clip_tri)( struct gl_context *ctx, GLuint v0, GLuint v1, GLuint v2, GLubyte mask )
187 {
188 TNLcontext *tnl = TNL_CONTEXT(ctx);
189 struct vertex_buffer *VB = &tnl->vb;
190 tnl_interp_func interp = tnl->Driver.Render.Interp;
191 GLuint newvert = VB->Count;
192 GLfloat (*coord)[4] = VB->ClipPtr->data;
193 GLuint pv = v2;
194 GLuint vlist[2][MAX_CLIPPED_VERTICES];
195 GLuint *inlist = vlist[0], *outlist = vlist[1];
196 GLuint n = 3;
197
198 ASSIGN_3V(inlist, v2, v0, v1 ); /* pv rotated to slot zero */
199
200 if (0) {
201 /* print pre-clip vertex coords */
202 GLuint i, j;
203 printf("pre clip:\n");
204 for (i = 0; i < n; i++) {
205 j = inlist[i];
206 printf(" %u: %u: %f, %f, %f, %f\n",
207 i, j,
208 coord[j][0], coord[j][1], coord[j][2], coord[j][3]);
209 assert(!util_is_inf_or_nan(coord[j][0]));
210 assert(!util_is_inf_or_nan(coord[j][1]));
211 assert(!util_is_inf_or_nan(coord[j][2]));
212 assert(!util_is_inf_or_nan(coord[j][3]));
213 }
214 }
215
216
217 if (mask & CLIP_FRUSTUM_BITS) {
218 POLY_CLIP( CLIP_RIGHT_BIT, -1, 0, 0, 1 );
219 POLY_CLIP( CLIP_LEFT_BIT, 1, 0, 0, 1 );
220 POLY_CLIP( CLIP_TOP_BIT, 0, -1, 0, 1 );
221 POLY_CLIP( CLIP_BOTTOM_BIT, 0, 1, 0, 1 );
222 POLY_CLIP( CLIP_FAR_BIT, 0, 0, -1, 1 );
223 POLY_CLIP( CLIP_NEAR_BIT, 0, 0, 1, 1 );
224 }
225
226 if (mask & CLIP_USER_BIT) {
227 GLbitfield enabled = ctx->Transform.ClipPlanesEnabled;
228 while (enabled) {
229 const int p = u_bit_scan(&enabled);
230 const GLfloat a = ctx->Transform._ClipUserPlane[p][0];
231 const GLfloat b = ctx->Transform._ClipUserPlane[p][1];
232 const GLfloat c = ctx->Transform._ClipUserPlane[p][2];
233 const GLfloat d = ctx->Transform._ClipUserPlane[p][3];
234 POLY_CLIP( CLIP_USER_BIT, a, b, c, d );
235 }
236 }
237
238 if (ctx->Light.ShadeModel == GL_FLAT) {
239 if (pv != inlist[0]) {
240 assert( inlist[0] >= VB->Count );
241 tnl->Driver.Render.CopyPV( ctx, inlist[0], pv );
242 }
243 }
244
245 if (0) {
246 /* print post-clip vertex coords */
247 GLuint i, j;
248 printf("post clip:\n");
249 for (i = 0; i < n; i++) {
250 j = inlist[i];
251 printf(" %u: %u: %f, %f, %f, %f\n",
252 i, j,
253 coord[j][0], coord[j][1], coord[j][2], coord[j][3]);
254 }
255 }
256
257 tnl->Driver.Render.ClippedPolygon( ctx, inlist, n );
258 }
259
260
261 /* Clip a quad against the viewport and user clip planes.
262 */
263 static inline void
TAG(clip_quad)264 TAG(clip_quad)( struct gl_context *ctx, GLuint v0, GLuint v1, GLuint v2, GLuint v3,
265 GLubyte mask )
266 {
267 TNLcontext *tnl = TNL_CONTEXT(ctx);
268 struct vertex_buffer *VB = &tnl->vb;
269 tnl_interp_func interp = tnl->Driver.Render.Interp;
270 GLuint newvert = VB->Count;
271 GLfloat (*coord)[4] = VB->ClipPtr->data;
272 GLuint pv = v3;
273 GLuint vlist[2][MAX_CLIPPED_VERTICES];
274 GLuint *inlist = vlist[0], *outlist = vlist[1];
275 GLuint n = 4;
276
277 ASSIGN_4V(inlist, v3, v0, v1, v2 ); /* pv rotated to slot zero */
278
279 if (mask & CLIP_FRUSTUM_BITS) {
280 POLY_CLIP( CLIP_RIGHT_BIT, -1, 0, 0, 1 );
281 POLY_CLIP( CLIP_LEFT_BIT, 1, 0, 0, 1 );
282 POLY_CLIP( CLIP_TOP_BIT, 0, -1, 0, 1 );
283 POLY_CLIP( CLIP_BOTTOM_BIT, 0, 1, 0, 1 );
284 POLY_CLIP( CLIP_FAR_BIT, 0, 0, -1, 1 );
285 POLY_CLIP( CLIP_NEAR_BIT, 0, 0, 1, 1 );
286 }
287
288 if (mask & CLIP_USER_BIT) {
289 GLbitfield enabled = ctx->Transform.ClipPlanesEnabled;
290 while (enabled) {
291 const int p = u_bit_scan(&enabled);
292 const GLfloat a = ctx->Transform._ClipUserPlane[p][0];
293 const GLfloat b = ctx->Transform._ClipUserPlane[p][1];
294 const GLfloat c = ctx->Transform._ClipUserPlane[p][2];
295 const GLfloat d = ctx->Transform._ClipUserPlane[p][3];
296 POLY_CLIP( CLIP_USER_BIT, a, b, c, d );
297 }
298 }
299
300 if (ctx->Light.ShadeModel == GL_FLAT) {
301 if (pv != inlist[0]) {
302 assert( inlist[0] >= VB->Count );
303 tnl->Driver.Render.CopyPV( ctx, inlist[0], pv );
304 }
305 }
306
307 tnl->Driver.Render.ClippedPolygon( ctx, inlist, n );
308 }
309
310 #undef W
311 #undef Z
312 #undef Y
313 #undef X
314 #undef SIZE
315 #undef TAG
316 #undef POLY_CLIP
317 #undef LINE_CLIP
318