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 "program/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_clip.h"
  43
  44
  45
  46 static void brw_clip_line_alloc_regs( struct brw_clip_compile *c )
  47 {
  48    struct brw_context *brw = c->func.brw;
  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    c->reg.vertex_src_mask = retype(brw_vec1_grf(i, 0), BRW_REGISTER_TYPE_UD);
  89    c->reg.clipdistance_offset = retype(brw_vec1_grf(i, 1), BRW_REGISTER_TYPE_W);
  90    i++;
  91
  92    if (brw->gen == 5) {
  93       c->reg.ff_sync = retype(brw_vec1_grf(i, 0), BRW_REGISTER_TYPE_UD);
  94       i++;
  95    }
  96
  97    c->first_tmp = i;
  98    c->last_tmp = i;
  99
 100    c->prog_data.urb_read_length = c->nr_regs; /* ? */
 101    c->prog_data.total_grf = i;
 102 }
 103
 104
 105 /* Line clipping, more or less following the following algorithm:
 106  *
 107  *  for (p=0;p<MAX_PLANES;p++) {
 108  *     if (clipmask & (1 << p)) {
 109  *        GLfloat dp0 = DOTPROD( vtx0, plane[p] );
 110  *        GLfloat dp1 = DOTPROD( vtx1, plane[p] );
 111  *
 112  *        if (IS_NEGATIVE(dp1)) {
 113  *           GLfloat t = dp1 / (dp1 - dp0);
 114  *           if (t > t1) t1 = t;
 115  *        } else {
 116  *           GLfloat t = dp0 / (dp0 - dp1);
 117  *           if (t > t0) t0 = t;
 118  *        }
 119  *
 120  *        if (t0 + t1 >= 1.0)
 121  *           return;
 122  *     }
 123  *  }
 124  *
 125  *  interp( ctx, newvtx0, vtx0, vtx1, t0 );
 126  *  interp( ctx, newvtx1, vtx1, vtx0, t1 );
 127  *
 128  */
 129 static void clip_and_emit_line( struct brw_clip_compile *c )
 130 {
 131    struct brw_compile *p = &c->func;
 132    struct brw_context *brw = p->brw;
 133    struct brw_indirect vtx0     = brw_indirect(0, 0);
 134    struct brw_indirect vtx1      = brw_indirect(1, 0);
 135    struct brw_indirect newvtx0   = brw_indirect(2, 0);
 136    struct brw_indirect newvtx1   = brw_indirect(3, 0);
 137    struct brw_indirect plane_ptr = brw_indirect(4, 0);
 138    struct brw_reg v1_null_ud = retype(vec1(brw_null_reg()), BRW_REGISTER_TYPE_UD);
 139    GLuint hpos_offset = brw_varying_to_offset(&c->vue_map, VARYING_SLOT_POS);
 140    GLint clipdist0_offset = c->key.nr_userclip
 141       ? brw_varying_to_offset(&c->vue_map, VARYING_SLOT_CLIP_DIST0)
 142       : 0;
 143
 144    brw_MOV(p, get_addr_reg(vtx0),      brw_address(c->reg.vertex[0]));
 145    brw_MOV(p, get_addr_reg(vtx1),      brw_address(c->reg.vertex[1]));
 146    brw_MOV(p, get_addr_reg(newvtx0),   brw_address(c->reg.vertex[2]));
 147    brw_MOV(p, get_addr_reg(newvtx1),   brw_address(c->reg.vertex[3]));
 148    brw_MOV(p, get_addr_reg(plane_ptr), brw_clip_plane0_address(c));
 149
 150    /* Note: init t0, t1 together:
 151     */
 152    brw_MOV(p, vec2(c->reg.t0), brw_imm_f(0));
 153
 154    brw_clip_init_planes(c);
 155    brw_clip_init_clipmask(c);
 156
 157    /* -ve rhw workaround */
 158    if (brw->has_negative_rhw_bug) {
 159       brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 160       brw_AND(p, brw_null_reg(), get_element_ud(c->reg.R0, 2),
 161               brw_imm_ud(1<<20));
 162       brw_OR(p, c->reg.planemask, c->reg.planemask, brw_imm_ud(0x3f));
 163    }
 164
 165    brw_set_predicate_control(p, BRW_PREDICATE_NONE);
 166
 167    /* Set the initial vertex source mask: The first 6 planes are the bounds
 168     * of the view volume; the next 8 planes are the user clipping planes.
 169     */
 170    brw_MOV(p, c->reg.vertex_src_mask, brw_imm_ud(0x3fc0));
 171
 172    /* Set the initial clipdistance offset to be 6 floats before gl_ClipDistance[0].
 173     * We'll increment 6 times before we start hitting actual user clipping. */
 174    brw_MOV(p, c->reg.clipdistance_offset, brw_imm_d(clipdist0_offset - 6*sizeof(float)));
 175
 176    brw_DO(p, BRW_EXECUTE_1);
 177    {
 178       /* if (planemask & 1)
 179        */
 180       brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 181       brw_AND(p, v1_null_ud, c->reg.planemask, brw_imm_ud(1));
 182
 183       brw_IF(p, BRW_EXECUTE_1);
 184       {
 185          brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 186          brw_AND(p, v1_null_ud, c->reg.vertex_src_mask, brw_imm_ud(1));
 187          brw_IF(p, BRW_EXECUTE_1);
 188          {
 189             /* user clip distance: just fetch the correct float from each vertex */
 190             struct brw_indirect temp_ptr = brw_indirect(7, 0);
 191             brw_ADD(p, get_addr_reg(temp_ptr), get_addr_reg(vtx0), c->reg.clipdistance_offset);
 192             brw_MOV(p, c->reg.dp0, deref_1f(temp_ptr, 0));
 193             brw_ADD(p, get_addr_reg(temp_ptr), get_addr_reg(vtx1), c->reg.clipdistance_offset);
 194             brw_MOV(p, c->reg.dp1, deref_1f(temp_ptr, 0));
 195          }
 196          brw_ELSE(p);
 197          {
 198             /* fixed plane: fetch the hpos, dp4 against the plane. */
 199             if (c->key.nr_userclip)
 200                brw_MOV(p, c->reg.plane_equation, deref_4f(plane_ptr, 0));
 201             else
 202                brw_MOV(p, c->reg.plane_equation, deref_4b(plane_ptr, 0));
 203
 204             brw_DP4(p, vec4(c->reg.dp0), deref_4f(vtx0, hpos_offset), c->reg.plane_equation);
 205             brw_DP4(p, vec4(c->reg.dp1), deref_4f(vtx1, hpos_offset), c->reg.plane_equation);
 206          }
 207          brw_ENDIF(p);
 208
 209          brw_CMP(p, brw_null_reg(), BRW_CONDITIONAL_L, vec1(c->reg.dp1), brw_imm_f(0.0f));
 210
 211          brw_IF(p, BRW_EXECUTE_1);
 212          {
 213              /*
 214               * Both can be negative on GM965/G965 due to RHW workaround
 215               * if so, this object should be rejected.
 216               */
 217              if (brw->has_negative_rhw_bug) {
 218                  brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_LE, c->reg.dp0, brw_imm_f(0.0));
 219                  brw_IF(p, BRW_EXECUTE_1);
 220                  {
 221                      brw_clip_kill_thread(c);
 222                  }
 223                  brw_ENDIF(p);
 224              }
 225
 226              brw_ADD(p, c->reg.t, c->reg.dp1, negate(c->reg.dp0));
 227              brw_math_invert(p, c->reg.t, c->reg.t);
 228              brw_MUL(p, c->reg.t, c->reg.t, c->reg.dp1);
 229
 230              brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_G, c->reg.t, c->reg.t1 );
 231              brw_MOV(p, c->reg.t1, c->reg.t);
 232              brw_set_predicate_control(p, BRW_PREDICATE_NONE);
 233          }
 234          brw_ELSE(p);
 235          {
 236              /* Coming back in.  We know that both cannot be negative
 237               * because the line would have been culled in that case.
 238               */
 239
 240              /* If both are positive, do nothing */
 241              /* Only on GM965/G965 */
 242              if (brw->has_negative_rhw_bug) {
 243                  brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_L, c->reg.dp0, brw_imm_f(0.0));
 244                  brw_IF(p, BRW_EXECUTE_1);
 245              }
 246
 247              {
 248                  brw_ADD(p, c->reg.t, c->reg.dp0, negate(c->reg.dp1));
 249                  brw_math_invert(p, c->reg.t, c->reg.t);
 250                  brw_MUL(p, c->reg.t, c->reg.t, c->reg.dp0);
 251
 252                  brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_G, c->reg.t, c->reg.t0 );
 253                  brw_MOV(p, c->reg.t0, c->reg.t);
 254                  brw_set_predicate_control(p, BRW_PREDICATE_NONE);
 255              }
 256
 257              if (brw->has_negative_rhw_bug) {
 258                  brw_ENDIF(p);
 259              }
 260          }
 261          brw_ENDIF(p);
 262       }
 263       brw_ENDIF(p);
 264
 265       /* plane_ptr++;
 266        */
 267       brw_ADD(p, get_addr_reg(plane_ptr), get_addr_reg(plane_ptr), brw_clip_plane_stride(c));
 268
 269       /* while (planemask>>=1) != 0
 270        */
 271       brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 272       brw_SHR(p, c->reg.planemask, c->reg.planemask, brw_imm_ud(1));
 273       brw_SHR(p, c->reg.vertex_src_mask, c->reg.vertex_src_mask, brw_imm_ud(1));
 274       brw_ADD(p, c->reg.clipdistance_offset, c->reg.clipdistance_offset, brw_imm_w(sizeof(float)));
 275    }
 276    brw_WHILE(p);
 277
 278    brw_ADD(p, c->reg.t, c->reg.t0, c->reg.t1);
 279    brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_L, c->reg.t, brw_imm_f(1.0));
 280    brw_IF(p, BRW_EXECUTE_1);
 281    {
 282       brw_clip_interp_vertex(c, newvtx0, vtx0, vtx1, c->reg.t0, false);
 283       brw_clip_interp_vertex(c, newvtx1, vtx1, vtx0, c->reg.t1, false);
 284
 285       brw_clip_emit_vue(c, newvtx0, BRW_URB_WRITE_ALLOCATE_COMPLETE,
 286                         (_3DPRIM_LINESTRIP << URB_WRITE_PRIM_TYPE_SHIFT)
 287                         | URB_WRITE_PRIM_START);
 288       brw_clip_emit_vue(c, newvtx1, BRW_URB_WRITE_EOT_COMPLETE,
 289                         (_3DPRIM_LINESTRIP << URB_WRITE_PRIM_TYPE_SHIFT)
 290                         | URB_WRITE_PRIM_END);
 291    }
 292    brw_ENDIF(p);
 293    brw_clip_kill_thread(c);
 294 }
 295
 296
 297
 298 void brw_emit_line_clip( struct brw_clip_compile *c )
 299 {
 300    brw_clip_line_alloc_regs(c);
 301    brw_clip_init_ff_sync(c);
 302
 303    if (c->has_flat_shading) {
 304       if (c->key.pv_first)
 305          brw_clip_copy_flatshaded_attributes(c, 1, 0);
 306       else
 307          brw_clip_copy_flatshaded_attributes(c, 0, 1);
 308    }
 309
 310    clip_and_emit_line(c);
 311 }