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 intel_context *intel = &c->func.brw->intel;
  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    if (intel->needs_ff_sync) {
  89       c->reg.ff_sync = retype(brw_vec1_grf(i, 0), BRW_REGISTER_TYPE_UD);
  90       i++;
  91    }
  92
  93    c->first_tmp = i;
  94    c->last_tmp = i;
  95
  96    c->prog_data.urb_read_length = c->nr_regs; /* ? */
  97    c->prog_data.total_grf = i;
  98 }
  99
 100
 101
 102 /* Line clipping, more or less following the following algorithm:
 103  *
 104  *  for (p=0;p<MAX_PLANES;p++) {
 105  *     if (clipmask & (1 << p)) {
 106  *        GLfloat dp0 = DOTPROD( vtx0, plane[p] );
 107  *        GLfloat dp1 = DOTPROD( vtx1, plane[p] );
 108  *
 109  *        if (IS_NEGATIVE(dp1)) {
 110  *           GLfloat t = dp1 / (dp1 - dp0);
 111  *           if (t > t1) t1 = t;
 112  *        } else {
 113  *           GLfloat t = dp0 / (dp0 - dp1);
 114  *           if (t > t0) t0 = t;
 115  *        }
 116  *
 117  *        if (t0 + t1 >= 1.0)
 118  *           return;
 119  *     }
 120  *  }
 121  *
 122  *  interp( ctx, newvtx0, vtx0, vtx1, t0 );
 123  *  interp( ctx, newvtx1, vtx1, vtx0, t1 );
 124  *
 125  */
 126 static void clip_and_emit_line( struct brw_clip_compile *c )
 127 {
 128    struct brw_compile *p = &c->func;
 129    struct brw_context *brw = p->brw;
 130    struct brw_indirect vtx0     = brw_indirect(0, 0);
 131    struct brw_indirect vtx1      = brw_indirect(1, 0);
 132    struct brw_indirect newvtx0   = brw_indirect(2, 0);
 133    struct brw_indirect newvtx1   = brw_indirect(3, 0);
 134    struct brw_indirect plane_ptr = brw_indirect(4, 0);
 135    struct brw_reg v1_null_ud = retype(vec1(brw_null_reg()), BRW_REGISTER_TYPE_UD);
 136    GLuint hpos_offset = brw_varying_to_offset(&c->vue_map, VARYING_SLOT_POS);
 137
 138    brw_MOV(p, get_addr_reg(vtx0),      brw_address(c->reg.vertex[0]));
 139    brw_MOV(p, get_addr_reg(vtx1),      brw_address(c->reg.vertex[1]));
 140    brw_MOV(p, get_addr_reg(newvtx0),   brw_address(c->reg.vertex[2]));
 141    brw_MOV(p, get_addr_reg(newvtx1),   brw_address(c->reg.vertex[3]));
 142    brw_MOV(p, get_addr_reg(plane_ptr), brw_clip_plane0_address(c));
 143
 144    /* Note: init t0, t1 together:
 145     */
 146    brw_MOV(p, vec2(c->reg.t0), brw_imm_f(0));
 147
 148    brw_clip_init_planes(c);
 149    brw_clip_init_clipmask(c);
 150
 151    /* -ve rhw workaround */
 152    if (brw->has_negative_rhw_bug) {
 153       brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 154       brw_AND(p, brw_null_reg(), get_element_ud(c->reg.R0, 2),
 155               brw_imm_ud(1<<20));
 156       brw_OR(p, c->reg.planemask, c->reg.planemask, brw_imm_ud(0x3f));
 157    }
 158
 159    brw_set_predicate_control(p, BRW_PREDICATE_NONE);
 160
 161    brw_DO(p, BRW_EXECUTE_1);
 162    {
 163       /* if (planemask & 1)
 164        */
 165       brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 166       brw_AND(p, v1_null_ud, c->reg.planemask, brw_imm_ud(1));
 167
 168       brw_IF(p, BRW_EXECUTE_1);
 169       {
 170          if (c->key.nr_userclip)
 171             brw_MOV(p, c->reg.plane_equation, deref_4f(plane_ptr, 0));
 172          else
 173             brw_MOV(p, c->reg.plane_equation, deref_4b(plane_ptr, 0));
 174
 175          /* dp = DP4(vtx->position, plane)
 176           */
 177          brw_DP4(p, vec4(c->reg.dp0), deref_4f(vtx0, hpos_offset), c->reg.plane_equation);
 178
 179          /* if (IS_NEGATIVE(dp1))
 180           */
 181          brw_set_conditionalmod(p, BRW_CONDITIONAL_L);
 182          brw_DP4(p, vec4(c->reg.dp1), deref_4f(vtx1, hpos_offset), c->reg.plane_equation);
 183          brw_IF(p, BRW_EXECUTE_1);
 184          {
 185              /*
 186               * Both can be negative on GM965/G965 due to RHW workaround
 187               * if so, this object should be rejected.
 188               */
 189              if (brw->has_negative_rhw_bug) {
 190                  brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_LE, c->reg.dp0, brw_imm_f(0.0));
 191                  brw_IF(p, BRW_EXECUTE_1);
 192                  {
 193                      brw_clip_kill_thread(c);
 194                  }
 195                  brw_ENDIF(p);
 196              }
 197
 198              brw_ADD(p, c->reg.t, c->reg.dp1, negate(c->reg.dp0));
 199              brw_math_invert(p, c->reg.t, c->reg.t);
 200              brw_MUL(p, c->reg.t, c->reg.t, c->reg.dp1);
 201
 202              brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_G, c->reg.t, c->reg.t1 );
 203              brw_MOV(p, c->reg.t1, c->reg.t);
 204              brw_set_predicate_control(p, BRW_PREDICATE_NONE);
 205          }
 206          brw_ELSE(p);
 207          {
 208              /* Coming back in.  We know that both cannot be negative
 209               * because the line would have been culled in that case.
 210               */
 211
 212              /* If both are positive, do nothing */
 213              /* Only on GM965/G965 */
 214              if (brw->has_negative_rhw_bug) {
 215                  brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_L, c->reg.dp0, brw_imm_f(0.0));
 216                  brw_IF(p, BRW_EXECUTE_1);
 217              }
 218
 219              {
 220                  brw_ADD(p, c->reg.t, c->reg.dp0, negate(c->reg.dp1));
 221                  brw_math_invert(p, c->reg.t, c->reg.t);
 222                  brw_MUL(p, c->reg.t, c->reg.t, c->reg.dp0);
 223
 224                  brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_G, c->reg.t, c->reg.t0 );
 225                  brw_MOV(p, c->reg.t0, c->reg.t);
 226                  brw_set_predicate_control(p, BRW_PREDICATE_NONE);
 227              }
 228
 229              if (brw->has_negative_rhw_bug) {
 230                  brw_ENDIF(p);
 231              }
 232          }
 233          brw_ENDIF(p);
 234       }
 235       brw_ENDIF(p);
 236
 237       /* plane_ptr++;
 238        */
 239       brw_ADD(p, get_addr_reg(plane_ptr), get_addr_reg(plane_ptr), brw_clip_plane_stride(c));
 240
 241       /* while (planemask>>=1) != 0
 242        */
 243       brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 244       brw_SHR(p, c->reg.planemask, c->reg.planemask, brw_imm_ud(1));
 245    }
 246    brw_WHILE(p);
 247
 248    brw_ADD(p, c->reg.t, c->reg.t0, c->reg.t1);
 249    brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_L, c->reg.t, brw_imm_f(1.0));
 250    brw_IF(p, BRW_EXECUTE_1);
 251    {
 252       brw_clip_interp_vertex(c, newvtx0, vtx0, vtx1, c->reg.t0, false);
 253       brw_clip_interp_vertex(c, newvtx1, vtx1, vtx0, c->reg.t1, false);
 254
 255       brw_clip_emit_vue(c, newvtx0, 1, 0,
 256                         (_3DPRIM_LINESTRIP << URB_WRITE_PRIM_TYPE_SHIFT)
 257                         | URB_WRITE_PRIM_START);
 258       brw_clip_emit_vue(c, newvtx1, 0, 1,
 259                         (_3DPRIM_LINESTRIP << URB_WRITE_PRIM_TYPE_SHIFT)
 260                         | URB_WRITE_PRIM_END);
 261    }
 262    brw_ENDIF(p);
 263    brw_clip_kill_thread(c);
 264 }
 265
 266
 267
 268 void brw_emit_line_clip( struct brw_clip_compile *c )
 269 {
 270    brw_clip_line_alloc_regs(c);
 271    brw_clip_init_ff_sync(c);
 272
 273    if (c->key.do_flat_shading) {
 274       if (c->key.pv_first)
 275          brw_clip_copy_colors(c, 1, 0);
 276       else
 277          brw_clip_copy_colors(c, 0, 1);
 278    }
 279
 280    clip_and_emit_line(c);
 281 }