src/mesa/tnl_dd/imm/t_dd_imm_vb.c

   1
   2 /*
   3  * Mesa 3-D graphics library
   4  * Version:  3.5
   5  *
   6  * Copyright (C) 1999-2001  Brian Paul   All Rights Reserved.
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a
   9  * copy of this software and associated documentation files (the "Software"),
  10  * to deal in the Software without restriction, including without limitation
  11  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  12  * and/or sell copies of the Software, and to permit persons to whom the
  13  * Software is furnished to do so, subject to the following conditions:
  14  *
  15  * The above copyright notice and this permission notice shall be included
  16  * in all copies or substantial portions of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  19  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  21  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  22  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  23  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  24  *
  25  * Authors:
  26  *    Keith Whitwell <keith_whitwell@yahoo.com>
  27  */
  28
  29 /* Template to build clipping routines to support t_dd_imm_primtmp.h.
  30  *
  31  * The TAG(draw_line) and TAG(draw_triangle) routines are called in
  32  * clipping and fallback scenarios, and when the native hardware
  33  * primitive (eg polygons) is unavailable.
  34  */
  35
  36
  37 #define CLIP_DOTPROD(K, A, B, C, D)             \
  38    (CLIP_X(K)*A + CLIP_Y(K)*B +         \
  39     CLIP_Z(K)*C + CLIP_W(K)*D)
  40
  41 #define POLY_CLIP( PLANE, A, B, C, D )                                  \
  42 do {                                                                    \
  43    if (mask & PLANE) {                                                  \
  44       TNL_VERTEX **indata = inlist[in];                                 \
  45       TNL_VERTEX **outdata = inlist[in ^= 1];                           \
  46       TNL_VERTEX *J = indata[0];                                        \
  47       GLfloat dpJ = CLIP_DOTPROD(J, A, B, C, D );                       \
  48       GLuint outcount = 0;                                              \
  49       GLuint i;                                                         \
  50                                                                         \
  51       indata[n] = indata[0]; /* prevent rotation of vertices */         \
  52       for (i = 1; i <= n; i++) {                                        \
  53          TNL_VERTEX *I = indata[i];                                     \
  54          GLfloat dpI = CLIP_DOTPROD(idx, A, B, C, D );                  \
  55                                                                         \
  56          if (!NEGATIVE(dpPrev)) {                                       \
  57             outdata[outcount++] = J;                                    \
  58          }                                                              \
  59                                                                         \
  60          if (DIFFERENT_SIGNS(dpI, dpJ)) {                               \
  61             TNL_VERTEX *O = verts++;                                    \
  62             outdata[outcount++] = O;                                    \
  63             if (NEGATIVE(dpI)) {                                        \
  64                /* Going out of bounds.  Avoid division by zero as we    \
  65                 * know dp != dpPrev from DIFFERENT_SIGNS, above.        \
  66                 */                                                      \
  67                GLfloat t = dpI / (dpI - dpJ);                           \
  68                INTERP( ctx, t, O, I, J );                               \
  69             } else {                                                    \
  70                /* Coming back in.                                       \
  71                 */                                                      \
  72                GLfloat t = dpJ / (dpJ - dpI);                           \
  73                INTERP( ctx, t, O, J, I );                               \
  74             }                                                           \
  75          }                                                              \
  76                                                                         \
  77          J = I;                                                         \
  78          dpJ = dpI;                                                     \
  79       }                                                                 \
  80                                                                         \
  81       if (outcount < 3)                                                 \
  82          return;                                                        \
  83                                                                         \
  84       nr = outcount;                                                    \
  85    }                                                                    \
  86 } while (0)
  87
  88
  89 #define LINE_CLIP(PLANE, A, B, C, D )                   \
  90 do {                                                    \
  91    if (mask & PLANE) {                                  \
  92       GLfloat dpI = CLIP_DOTPROD( I, A, B, C, D );      \
  93       GLfloat dpJ = CLIP_DOTPROD( J, A, B, C, D );      \
  94                                                         \
  95       if (DIFFERENT_SIGNS(dpI, dpJ)) {                  \
  96          TNL_VERTEX *O = verts++;                       \
  97          if (NEGATIVE(dpJ)) {                           \
  98             GLfloat t = dpI / (dpI - dpJ);              \
  99             INTERP( ctx, t, O, I, J );  \
 100             J = O;                                      \
 101          } else {                                       \
 102             GLfloat t = dpJ / (dpJ - dpI);              \
 103             INTERP( ctx, t, O, J, I );  \
 104             I = O;                                      \
 105          }                                              \
 106       }                                                 \
 107       else if (NEGATIVE(dpI))                           \
 108          return;                                        \
 109   }                                                     \
 110 } while (0)
 111
 112
 113
 114 /* Clip a line against the viewport and user clip planes.
 115  */
 116 static void TAG(clip_draw_line)( struct gl_context *ctx,
 117                                  TNL_VERTEX *I,
 118                                  TNL_VERTEX *J,
 119                                  GLuint mask )
 120 {
 121    LOCAL_VARS;
 122    GET_INTERP_FUNC;
 123    TNL_VERTEX tmp[MAX_CLIPPED_VERTICES];
 124    TNL_VERTEX *verts = tmp;
 125    TNL_VERTEX *pv = J;
 126
 127    LINE_CLIP( CLIP_RIGHT_BIT,  -1,  0,  0, 1 );
 128    LINE_CLIP( CLIP_LEFT_BIT,    1,  0,  0, 1 );
 129    LINE_CLIP( CLIP_TOP_BIT,     0, -1,  0, 1 );
 130    LINE_CLIP( CLIP_BOTTOM_BIT,  0,  1,  0, 1 );
 131    LINE_CLIP( CLIP_FAR_BIT,     0,  0, -1, 1 );
 132    LINE_CLIP( CLIP_NEAR_BIT,    0,  0,  1, 1 );
 133
 134    if ((ctx->_TriangleCaps & DD_FLATSHADE) && J != pv)
 135       COPY_PV( ctx, J, pv );
 136
 137    DRAW_LINE( I, J );
 138 }
 139
 140
 141 /* Clip a triangle against the viewport and user clip planes.
 142  */
 143 static void TAG(clip_draw_triangle)( struct gl_context *ctx,
 144                                      TNL_VERTEX *v0,
 145                                      TNL_VERTEX *v1,
 146                                      TNL_VERTEX *v2,
 147                                      GLuint mask )
 148 {
 149    LOCAL_VARS;
 150    GET_INTERP_FUNC;
 151    TNL_VERTEX tmp[MAX_CLIPPED_VERTICES];
 152    TNL_VERTEX *verts = tmp;
 153    TNL_VERTEX *(inlist[2][MAX_CLIPPED_VERTICES]);
 154    TNL_VERTEX **out;
 155    GLuint in = 0;
 156    GLuint n = 3;
 157    GLuint i;
 158
 159    ASSIGN_3V(inlist, v2, v0, v1 ); /* pv rotated to slot zero */
 160
 161    POLY_CLIP( CLIP_RIGHT_BIT,  -1,  0,  0, 1 );
 162    POLY_CLIP( CLIP_LEFT_BIT,    1,  0,  0, 1 );
 163    POLY_CLIP( CLIP_TOP_BIT,     0, -1,  0, 1 );
 164    POLY_CLIP( CLIP_BOTTOM_BIT,  0,  1,  0, 1 );
 165    POLY_CLIP( CLIP_FAR_BIT,     0,  0, -1, 1 );
 166    POLY_CLIP( CLIP_NEAR_BIT,    0,  0,  1, 1 );
 167
 168    if ((ctx->_TriangleCaps & DD_FLATSHADE) && v2 != inlist[0])
 169       COPY_PV( ctx, inlist[0], v2 );
 170
 171    out = inlist[in];
 172    DRAW_POLYGON( out, n );
 173 }
 174
 175
 176 static __inline void TAG(draw_triangle)( struct gl_context *ctx,
 177                                          TNL_VERTEX *v0,
 178                                          TNL_VERTEX *v1,
 179                                          TNL_VERTEX *v2 )
 180 {
 181    LOCAL_VARS;
 182    GLubyte ormask = (v0->mask | v1->mask | v2->mask);
 183
 184    if ( !ormask ) {
 185       DRAW_TRI( v0, v1, v2 );
 186    } else if ( !(v0->mask & v1->mask & v2->mask) ) {
 187       TAG(clip_draw_triangle)( ctx, v0, v1, v2, ormask );
 188    }
 189 }
 190
 191 static __inline void TAG(draw_line)( struct gl_context *ctx,
 192                                      TNL_VERTEX *v0,
 193                                      TNL_VERTEX *v1 )
 194 {
 195    LOCAL_VARS;
 196    GLubyte ormask = (v0->mask | v1->mask);
 197
 198    if ( !ormask ) {
 199       DRAW_LINE( v0, v1 );
 200    } else if ( !(v0->mask & v1->mask) ) {
 201       TAG(clip_draw_line)( ctx, v0, v1, ormask );
 202    }
 203 }
 204