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    struct intel_context *intel = &c->func.brw->intel;
  50    GLuint i = 0,j;
  51
  52    /* Register usage is static, precompute here:
  53     */
  54    c->reg.R0 = retype(brw_vec8_grf(i, 0), BRW_REGISTER_TYPE_UD); i++;
  55
  56    if (c->key.nr_userclip) {
  57       c->reg.fixed_planes = brw_vec4_grf(i, 0);
  58       i += (6 + c->key.nr_userclip + 1) / 2;
  59
  60       c->prog_data.curb_read_length = (6 + c->key.nr_userclip + 1) / 2;
  61    }
  62    else
  63       c->prog_data.curb_read_length = 0;
  64
  65
  66    /* Payload vertices plus space for more generated vertices:
  67     */
  68    for (j = 0; j < 4; j++) {
  69       c->reg.vertex[j] = brw_vec4_grf(i, 0);
  70       i += c->nr_regs;
  71    }
  72
  73    c->reg.t           = brw_vec1_grf(i, 0);
  74    c->reg.t0          = brw_vec1_grf(i, 1);
  75    c->reg.t1          = brw_vec1_grf(i, 2);
  76    c->reg.planemask   = retype(brw_vec1_grf(i, 3), BRW_REGISTER_TYPE_UD);
  77    c->reg.plane_equation = brw_vec4_grf(i, 4);
  78    i++;
  79
  80    c->reg.dp0         = brw_vec1_grf(i, 0); /* fixme - dp4 will clobber r.1,2,3 */
  81    c->reg.dp1         = brw_vec1_grf(i, 4);
  82    i++;
  83
  84    if (!c->key.nr_userclip) {
  85       c->reg.fixed_planes = brw_vec8_grf(i, 0);
  86       i++;
  87    }
  88
  89    if (intel->needs_ff_sync) {
  90       c->reg.ff_sync = retype(brw_vec1_grf(i, 0), BRW_REGISTER_TYPE_UD);
  91       i++;
  92    }
  93
  94    c->first_tmp = i;
  95    c->last_tmp = i;
  96
  97    c->prog_data.urb_read_length = c->nr_regs; /* ? */
  98    c->prog_data.total_grf = i;
  99 }
 100
 101
 102
 103 /* Line clipping, more or less following the following algorithm:
 104  *
 105  *  for (p=0;p<MAX_PLANES;p++) {
 106  *     if (clipmask & (1 << p)) {
 107  *        GLfloat dp0 = DOTPROD( vtx0, plane[p] );
 108  *        GLfloat dp1 = DOTPROD( vtx1, plane[p] );
 109  *
 110  *        if (IS_NEGATIVE(dp1)) {
 111  *           GLfloat t = dp1 / (dp1 - dp0);
 112  *           if (t > t1) t1 = t;
 113  *        } else {
 114  *           GLfloat t = dp0 / (dp0 - dp1);
 115  *           if (t > t0) t0 = t;
 116  *        }
 117  *
 118  *        if (t0 + t1 >= 1.0)
 119  *           return;
 120  *     }
 121  *  }
 122  *
 123  *  interp( ctx, newvtx0, vtx0, vtx1, t0 );
 124  *  interp( ctx, newvtx1, vtx1, vtx0, t1 );
 125  *
 126  */
 127 static void clip_and_emit_line( struct brw_clip_compile *c )
 128 {
 129    struct brw_compile *p = &c->func;
 130    struct brw_context *brw = p->brw;
 131    struct brw_indirect vtx0     = brw_indirect(0, 0);
 132    struct brw_indirect vtx1      = brw_indirect(1, 0);
 133    struct brw_indirect newvtx0   = brw_indirect(2, 0);
 134    struct brw_indirect newvtx1   = brw_indirect(3, 0);
 135    struct brw_indirect plane_ptr = brw_indirect(4, 0);
 136    struct brw_instruction *plane_loop;
 137    struct brw_instruction *plane_active;
 138    struct brw_instruction *is_negative;
 139    struct brw_instruction *is_neg2 = NULL;
 140    struct brw_instruction *not_culled;
 141    struct brw_reg v1_null_ud = retype(vec1(brw_null_reg()), BRW_REGISTER_TYPE_UD);
 142
 143    brw_MOV(p, get_addr_reg(vtx0),      brw_address(c->reg.vertex[0]));
 144    brw_MOV(p, get_addr_reg(vtx1),      brw_address(c->reg.vertex[1]));
 145    brw_MOV(p, get_addr_reg(newvtx0),   brw_address(c->reg.vertex[2]));
 146    brw_MOV(p, get_addr_reg(newvtx1),   brw_address(c->reg.vertex[3]));
 147    brw_MOV(p, get_addr_reg(plane_ptr), brw_clip_plane0_address(c));
 148
 149    /* Note: init t0, t1 together:
 150     */
 151    brw_MOV(p, vec2(c->reg.t0), brw_imm_f(0));
 152
 153    brw_clip_init_planes(c);
 154    brw_clip_init_clipmask(c);
 155
 156    /* -ve rhw workaround */
 157    if (brw->has_negative_rhw_bug) {
 158       brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 159       brw_AND(p, brw_null_reg(), get_element_ud(c->reg.R0, 2),
 160               brw_imm_ud(1<<20));
 161       brw_OR(p, c->reg.planemask, c->reg.planemask, brw_imm_ud(0x3f));
 162    }
 163
 164    brw_set_predicate_control(p, BRW_PREDICATE_NONE);
 165
 166    plane_loop = brw_DO(p, BRW_EXECUTE_1);
 167    {
 168       /* if (planemask & 1)
 169        */
 170       brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 171       brw_AND(p, v1_null_ud, c->reg.planemask, brw_imm_ud(1));
 172
 173       plane_active = brw_IF(p, BRW_EXECUTE_1);
 174       {
 175          if (c->key.nr_userclip)
 176             brw_MOV(p, c->reg.plane_equation, deref_4f(plane_ptr, 0));
 177          else
 178             brw_MOV(p, c->reg.plane_equation, deref_4b(plane_ptr, 0));
 179
 180          /* dp = DP4(vtx->position, plane)
 181           */
 182          brw_DP4(p, vec4(c->reg.dp0), deref_4f(vtx0, c->offset[VERT_RESULT_HPOS]), c->reg.plane_equation);
 183
 184          /* if (IS_NEGATIVE(dp1))
 185           */
 186          brw_set_conditionalmod(p, BRW_CONDITIONAL_L);
 187          brw_DP4(p, vec4(c->reg.dp1), deref_4f(vtx1, c->offset[VERT_RESULT_HPOS]), c->reg.plane_equation);
 188          is_negative = brw_IF(p, BRW_EXECUTE_1);
 189          {
 190              /*
 191               * Both can be negative on GM965/G965 due to RHW workaround
 192               * if so, this object should be rejected.
 193               */
 194              if (brw->has_negative_rhw_bug) {
 195                  brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_LE, c->reg.dp0, brw_imm_f(0.0));
 196                  is_neg2 = brw_IF(p, BRW_EXECUTE_1);
 197                  {
 198                      brw_clip_kill_thread(c);
 199                  }
 200                  brw_ENDIF(p, is_neg2);
 201              }
 202
 203              brw_ADD(p, c->reg.t, c->reg.dp1, negate(c->reg.dp0));
 204              brw_math_invert(p, c->reg.t, c->reg.t);
 205              brw_MUL(p, c->reg.t, c->reg.t, c->reg.dp1);
 206
 207              brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_G, c->reg.t, c->reg.t1 );
 208              brw_MOV(p, c->reg.t1, c->reg.t);
 209              brw_set_predicate_control(p, BRW_PREDICATE_NONE);
 210          }
 211          is_negative = brw_ELSE(p, is_negative);
 212          {
 213              /* Coming back in.  We know that both cannot be negative
 214               * because the line would have been culled in that case.
 215               */
 216
 217              /* If both are positive, do nothing */
 218              /* Only on GM965/G965 */
 219              if (brw->has_negative_rhw_bug) {
 220                  brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_L, c->reg.dp0, brw_imm_f(0.0));
 221                  is_neg2 = brw_IF(p, BRW_EXECUTE_1);
 222              }
 223
 224              {
 225                  brw_ADD(p, c->reg.t, c->reg.dp0, negate(c->reg.dp1));
 226                  brw_math_invert(p, c->reg.t, c->reg.t);
 227                  brw_MUL(p, c->reg.t, c->reg.t, c->reg.dp0);
 228
 229                  brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_G, c->reg.t, c->reg.t0 );
 230                  brw_MOV(p, c->reg.t0, c->reg.t);
 231                  brw_set_predicate_control(p, BRW_PREDICATE_NONE);
 232              }
 233
 234              if (brw->has_negative_rhw_bug) {
 235                  brw_ENDIF(p, is_neg2);
 236              }
 237          }
 238          brw_ENDIF(p, is_negative);
 239       }
 240       brw_ENDIF(p, plane_active);
 241
 242       /* plane_ptr++;
 243        */
 244       brw_ADD(p, get_addr_reg(plane_ptr), get_addr_reg(plane_ptr), brw_clip_plane_stride(c));
 245
 246       /* while (planemask>>=1) != 0
 247        */
 248       brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 249       brw_SHR(p, c->reg.planemask, c->reg.planemask, brw_imm_ud(1));
 250    }
 251    brw_WHILE(p, plane_loop);
 252
 253    brw_ADD(p, c->reg.t, c->reg.t0, c->reg.t1);
 254    brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_L, c->reg.t, brw_imm_f(1.0));
 255    not_culled = brw_IF(p, BRW_EXECUTE_1);
 256    {
 257       brw_clip_interp_vertex(c, newvtx0, vtx0, vtx1, c->reg.t0, GL_FALSE);
 258       brw_clip_interp_vertex(c, newvtx1, vtx1, vtx0, c->reg.t1, GL_FALSE);
 259
 260       brw_clip_emit_vue(c, newvtx0, 1, 0, (_3DPRIM_LINESTRIP << 2) | R02_PRIM_START);
 261       brw_clip_emit_vue(c, newvtx1, 0, 1, (_3DPRIM_LINESTRIP << 2) | R02_PRIM_END);
 262    }
 263    brw_ENDIF(p, not_culled);
 264    brw_clip_kill_thread(c);
 265 }
 266
 267
 268
 269 void brw_emit_line_clip( struct brw_clip_compile *c )
 270 {
 271    brw_clip_line_alloc_regs(c);
 272    brw_clip_init_ff_sync(c);
 273
 274    if (c->key.do_flat_shading) {
 275       if (c->key.pv_first)
 276          brw_clip_copy_colors(c, 1, 0);
 277       else
 278          brw_clip_copy_colors(c, 0, 1);
 279    }
 280
 281    clip_and_emit_line(c);
 282 }