• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
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(!IS_INF_OR_NAN(coord[j][0]));
210          assert(!IS_INF_OR_NAN(coord[j][1]));
211          assert(!IS_INF_OR_NAN(coord[j][2]));
212          assert(!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