src/mesa/drivers/dri/i965/brw_clip_line.c

   1 /*
   2  Copyright (C) Intel Corp.  2006.  All Rights Reserved.
   3  Intel funded Tungsten Graphics (http://www.tungstengraphics.com) to
   4  develop this 3D driver.
   5
   6  Permission is hereby granted, free of charge, to any person obtaining
   7  a copy of this software and associated documentation files (the
   8  "Software"), to deal in the Software without restriction, including
   9  without limitation the rights to use, copy, modify, merge, publish,
  10  distribute, sublicense, and/or sell copies of the Software, and to
  11  permit persons to whom the Software is furnished to do so, subject to
  12  the following conditions:
  13
  14  The above copyright notice and this permission notice (including the
  15  next paragraph) shall be included in all copies or substantial
  16  portions of the Software.
  17
  18  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  19  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  20  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  21  IN NO EVENT SHALL THE COPYRIGHT OWNER(S) AND/OR ITS SUPPLIERS BE
  22  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  23  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  24  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  25
  26  **********************************************************************/
  27  /*
  28   * Authors:
  29   *   Keith Whitwell <keith@tungstengraphics.com>
  30   */
  31
  32 #include "main/glheader.h"
  33 #include "main/macros.h"
  34 #include "main/enums.h"
  35 #include "shader/program.h"
  36
  37 #include "intel_batchbuffer.h"
  38
  39 #include "brw_defines.h"
  40 #include "brw_context.h"
  41 #include "brw_eu.h"
  42 #include "brw_util.h"
  43 #include "brw_clip.h"
  44
  45
  46
  47 static void brw_clip_line_alloc_regs( struct brw_clip_compile *c )
  48 {
  49    GLuint i = 0,j;
  50
  51    /* Register usage is static, precompute here:
  52     */
  53    c->reg.R0 = retype(brw_vec8_grf(i, 0), BRW_REGISTER_TYPE_UD); i++;
  54
  55    if (c->key.nr_userclip) {
  56       c->reg.fixed_planes = brw_vec4_grf(i, 0);
  57       i += (6 + c->key.nr_userclip + 1) / 2;
  58
  59       c->prog_data.curb_read_length = (6 + c->key.nr_userclip + 1) / 2;
  60    }
  61    else
  62       c->prog_data.curb_read_length = 0;
  63
  64
  65    /* Payload vertices plus space for more generated vertices:
  66     */
  67    for (j = 0; j < 4; j++) {
  68       c->reg.vertex[j] = brw_vec4_grf(i, 0);
  69       i += c->nr_regs;
  70    }
  71
  72    c->reg.t           = brw_vec1_grf(i, 0);
  73    c->reg.t0          = brw_vec1_grf(i, 1);
  74    c->reg.t1          = brw_vec1_grf(i, 2);
  75    c->reg.planemask   = retype(brw_vec1_grf(i, 3), BRW_REGISTER_TYPE_UD);
  76    c->reg.plane_equation = brw_vec4_grf(i, 4);
  77    i++;
  78
  79    c->reg.dp0         = brw_vec1_grf(i, 0); /* fixme - dp4 will clobber r.1,2,3 */
  80    c->reg.dp1         = brw_vec1_grf(i, 4);
  81    i++;
  82
  83    if (!c->key.nr_userclip) {
  84       c->reg.fixed_planes = brw_vec8_grf(i, 0);
  85       i++;
  86    }
  87
  88
  89    c->first_tmp = i;
  90    c->last_tmp = i;
  91
  92    c->prog_data.urb_read_length = c->nr_regs; /* ? */
  93    c->prog_data.total_grf = i;
  94 }
  95
  96
  97
  98 /* Line clipping, more or less following the following algorithm:
  99  *
 100  *  for (p=0;p<MAX_PLANES;p++) {
 101  *     if (clipmask & (1 << p)) {
 102  *        GLfloat dp0 = DOTPROD( vtx0, plane[p] );
 103  *        GLfloat dp1 = DOTPROD( vtx1, plane[p] );
 104  *
 105  *        if (IS_NEGATIVE(dp1)) {
 106  *           GLfloat t = dp1 / (dp1 - dp0);
 107  *           if (t > t1) t1 = t;
 108  *        } else {
 109  *           GLfloat t = dp0 / (dp0 - dp1);
 110  *           if (t > t0) t0 = t;
 111  *        }
 112  *
 113  *        if (t0 + t1 >= 1.0)
 114  *           return;
 115  *     }
 116  *  }
 117  *
 118  *  interp( ctx, newvtx0, vtx0, vtx1, t0 );
 119  *  interp( ctx, newvtx1, vtx1, vtx0, t1 );
 120  *
 121  */
 122 static void clip_and_emit_line( struct brw_clip_compile *c )
 123 {
 124    struct brw_compile *p = &c->func;
 125    struct brw_indirect vtx0     = brw_indirect(0, 0);
 126    struct brw_indirect vtx1      = brw_indirect(1, 0);
 127    struct brw_indirect newvtx0   = brw_indirect(2, 0);
 128    struct brw_indirect newvtx1   = brw_indirect(3, 0);
 129    struct brw_indirect plane_ptr = brw_indirect(4, 0);
 130    struct brw_instruction *plane_loop;
 131    struct brw_instruction *plane_active;
 132    struct brw_instruction *is_negative;
 133    struct brw_instruction *is_neg2;
 134    struct brw_instruction *not_culled;
 135    struct brw_reg v1_null_ud = retype(vec1(brw_null_reg()), BRW_REGISTER_TYPE_UD);
 136
 137    brw_MOV(p, get_addr_reg(vtx0),      brw_address(c->reg.vertex[0]));
 138    brw_MOV(p, get_addr_reg(vtx1),      brw_address(c->reg.vertex[1]));
 139    brw_MOV(p, get_addr_reg(newvtx0),   brw_address(c->reg.vertex[2]));
 140    brw_MOV(p, get_addr_reg(newvtx1),   brw_address(c->reg.vertex[3]));
 141    brw_MOV(p, get_addr_reg(plane_ptr), brw_clip_plane0_address(c));
 142
 143    /* Note: init t0, t1 together:
 144     */
 145    brw_MOV(p, vec2(c->reg.t0), brw_imm_f(0));
 146
 147    brw_clip_init_planes(c);
 148    brw_clip_init_clipmask(c);
 149
 150    /* -ve rhw workaround */
 151    if (!BRW_IS_G4X(p->brw)) {
 152       brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 153       brw_AND(p, brw_null_reg(), get_element_ud(c->reg.R0, 2),
 154               brw_imm_ud(1<<20));
 155       brw_OR(p, c->reg.planemask, c->reg.planemask, brw_imm_ud(0x3f));
 156    }
 157
 158    brw_set_predicate_control(p, BRW_PREDICATE_NONE);
 159
 160    plane_loop = brw_DO(p, BRW_EXECUTE_1);
 161    {
 162       /* if (planemask & 1)
 163        */
 164       brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 165       brw_AND(p, v1_null_ud, c->reg.planemask, brw_imm_ud(1));
 166
 167       plane_active = brw_IF(p, BRW_EXECUTE_1);
 168       {
 169          if (c->key.nr_userclip)
 170             brw_MOV(p, c->reg.plane_equation, deref_4f(plane_ptr, 0));
 171          else
 172             brw_MOV(p, c->reg.plane_equation, deref_4b(plane_ptr, 0));
 173
 174          /* dp = DP4(vtx->position, plane)
 175           */
 176          brw_DP4(p, vec4(c->reg.dp0), deref_4f(vtx0, c->offset[VERT_RESULT_HPOS]), c->reg.plane_equation);
 177
 178          /* if (IS_NEGATIVE(dp1))
 179           */
 180          brw_set_conditionalmod(p, BRW_CONDITIONAL_L);
 181          brw_DP4(p, vec4(c->reg.dp1), deref_4f(vtx1, c->offset[VERT_RESULT_HPOS]), c->reg.plane_equation);
 182          is_negative = brw_IF(p, BRW_EXECUTE_1);
 183          {
 184              /*
 185               * Both can be negative on GM965/G965 due to RHW workaround
 186               * if so, this object should be rejected.
 187               */
 188              if (!BRW_IS_G4X(p->brw)) {
 189                  brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_LE, c->reg.dp0, brw_imm_f(0.0));
 190                  is_neg2 = brw_IF(p, BRW_EXECUTE_1);
 191                  {
 192                      brw_clip_kill_thread(c);
 193                  }
 194                  brw_ENDIF(p, is_neg2);
 195              }
 196
 197              brw_ADD(p, c->reg.t, c->reg.dp1, negate(c->reg.dp0));
 198              brw_math_invert(p, c->reg.t, c->reg.t);
 199              brw_MUL(p, c->reg.t, c->reg.t, c->reg.dp1);
 200
 201              brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_G, c->reg.t, c->reg.t1 );
 202              brw_MOV(p, c->reg.t1, c->reg.t);
 203              brw_set_predicate_control(p, BRW_PREDICATE_NONE);
 204          }
 205          is_negative = brw_ELSE(p, is_negative);
 206          {
 207              /* Coming back in.  We know that both cannot be negative
 208               * because the line would have been culled in that case.
 209               */
 210
 211              /* If both are positive, do nothing */
 212              /* Only on GM965/G965 */
 213              if (!BRW_IS_G4X(p->brw)) {
 214                  brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_L, c->reg.dp0, brw_imm_f(0.0));
 215                  is_neg2 = brw_IF(p, BRW_EXECUTE_1);
 216              }
 217
 218              {
 219                  brw_ADD(p, c->reg.t, c->reg.dp0, negate(c->reg.dp1));
 220                  brw_math_invert(p, c->reg.t, c->reg.t);
 221                  brw_MUL(p, c->reg.t, c->reg.t, c->reg.dp0);
 222
 223                  brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_G, c->reg.t, c->reg.t0 );
 224                  brw_MOV(p, c->reg.t0, c->reg.t);
 225                  brw_set_predicate_control(p, BRW_PREDICATE_NONE);
 226              }
 227
 228              if (!BRW_IS_G4X(p->brw)) {
 229                  brw_ENDIF(p, is_neg2);
 230              }
 231          }
 232          brw_ENDIF(p, is_negative);
 233       }
 234       brw_ENDIF(p, plane_active);
 235
 236       /* plane_ptr++;
 237        */
 238       brw_ADD(p, get_addr_reg(plane_ptr), get_addr_reg(plane_ptr), brw_clip_plane_stride(c));
 239
 240       /* while (planemask>>=1) != 0
 241        */
 242       brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 243       brw_SHR(p, c->reg.planemask, c->reg.planemask, brw_imm_ud(1));
 244    }
 245    brw_WHILE(p, plane_loop);
 246
 247    brw_ADD(p, c->reg.t, c->reg.t0, c->reg.t1);
 248    brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_L, c->reg.t, brw_imm_f(1.0));
 249    not_culled = brw_IF(p, BRW_EXECUTE_1);
 250    {
 251       brw_clip_interp_vertex(c, newvtx0, vtx0, vtx1, c->reg.t0, GL_FALSE);
 252       brw_clip_interp_vertex(c, newvtx1, vtx1, vtx0, c->reg.t1, GL_FALSE);
 253
 254       brw_clip_emit_vue(c, newvtx0, 1, 0, (_3DPRIM_LINESTRIP << 2) | R02_PRIM_START);
 255       brw_clip_emit_vue(c, newvtx1, 0, 1, (_3DPRIM_LINESTRIP << 2) | R02_PRIM_END);
 256    }
 257    brw_ENDIF(p, not_culled);
 258    brw_clip_kill_thread(c);
 259 }
 260
 261
 262
 263 void brw_emit_line_clip( struct brw_clip_compile *c )
 264 {
 265    brw_clip_line_alloc_regs(c);
 266
 267    if (c->key.do_flat_shading)
 268       brw_clip_copy_colors(c, 0, 1);
 269
 270    clip_and_emit_line(c);
 271 }