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_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_instruction *plane_loop;
 136    struct brw_instruction *plane_active;
 137    struct brw_instruction *is_negative;
 138    struct brw_instruction *is_neg2 = NULL;
 139    struct brw_instruction *not_culled;
 140    struct brw_reg v1_null_ud = retype(vec1(brw_null_reg()), BRW_REGISTER_TYPE_UD);
 141
 142    brw_MOV(p, get_addr_reg(vtx0),      brw_address(c->reg.vertex[0]));
 143    brw_MOV(p, get_addr_reg(vtx1),      brw_address(c->reg.vertex[1]));
 144    brw_MOV(p, get_addr_reg(newvtx0),   brw_address(c->reg.vertex[2]));
 145    brw_MOV(p, get_addr_reg(newvtx1),   brw_address(c->reg.vertex[3]));
 146    brw_MOV(p, get_addr_reg(plane_ptr), brw_clip_plane0_address(c));
 147
 148    /* Note: init t0, t1 together:
 149     */
 150    brw_MOV(p, vec2(c->reg.t0), brw_imm_f(0));
 151
 152    brw_clip_init_planes(c);
 153    brw_clip_init_clipmask(c);
 154
 155    /* -ve rhw workaround */
 156    if (brw->has_negative_rhw_bug) {
 157       brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 158       brw_AND(p, brw_null_reg(), get_element_ud(c->reg.R0, 2),
 159               brw_imm_ud(1<<20));
 160       brw_OR(p, c->reg.planemask, c->reg.planemask, brw_imm_ud(0x3f));
 161    }
 162
 163    brw_set_predicate_control(p, BRW_PREDICATE_NONE);
 164
 165    plane_loop = brw_DO(p, BRW_EXECUTE_1);
 166    {
 167       /* if (planemask & 1)
 168        */
 169       brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 170       brw_AND(p, v1_null_ud, c->reg.planemask, brw_imm_ud(1));
 171
 172       plane_active = brw_IF(p, BRW_EXECUTE_1);
 173       {
 174          if (c->key.nr_userclip)
 175             brw_MOV(p, c->reg.plane_equation, deref_4f(plane_ptr, 0));
 176          else
 177             brw_MOV(p, c->reg.plane_equation, deref_4b(plane_ptr, 0));
 178
 179          /* dp = DP4(vtx->position, plane)
 180           */
 181          brw_DP4(p, vec4(c->reg.dp0), deref_4f(vtx0, c->offset[VERT_RESULT_HPOS]), c->reg.plane_equation);
 182
 183          /* if (IS_NEGATIVE(dp1))
 184           */
 185          brw_set_conditionalmod(p, BRW_CONDITIONAL_L);
 186          brw_DP4(p, vec4(c->reg.dp1), deref_4f(vtx1, c->offset[VERT_RESULT_HPOS]), c->reg.plane_equation);
 187          is_negative = brw_IF(p, BRW_EXECUTE_1);
 188          {
 189              /*
 190               * Both can be negative on GM965/G965 due to RHW workaround
 191               * if so, this object should be rejected.
 192               */
 193              if (brw->has_negative_rhw_bug) {
 194                  brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_LE, c->reg.dp0, brw_imm_f(0.0));
 195                  is_neg2 = brw_IF(p, BRW_EXECUTE_1);
 196                  {
 197                      brw_clip_kill_thread(c);
 198                  }
 199                  brw_ENDIF(p, is_neg2);
 200              }
 201
 202              brw_ADD(p, c->reg.t, c->reg.dp1, negate(c->reg.dp0));
 203              brw_math_invert(p, c->reg.t, c->reg.t);
 204              brw_MUL(p, c->reg.t, c->reg.t, c->reg.dp1);
 205
 206              brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_G, c->reg.t, c->reg.t1 );
 207              brw_MOV(p, c->reg.t1, c->reg.t);
 208              brw_set_predicate_control(p, BRW_PREDICATE_NONE);
 209          }
 210          is_negative = brw_ELSE(p, is_negative);
 211          {
 212              /* Coming back in.  We know that both cannot be negative
 213               * because the line would have been culled in that case.
 214               */
 215
 216              /* If both are positive, do nothing */
 217              /* Only on GM965/G965 */
 218              if (brw->has_negative_rhw_bug) {
 219                  brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_L, c->reg.dp0, brw_imm_f(0.0));
 220                  is_neg2 = brw_IF(p, BRW_EXECUTE_1);
 221              }
 222
 223              {
 224                  brw_ADD(p, c->reg.t, c->reg.dp0, negate(c->reg.dp1));
 225                  brw_math_invert(p, c->reg.t, c->reg.t);
 226                  brw_MUL(p, c->reg.t, c->reg.t, c->reg.dp0);
 227
 228                  brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_G, c->reg.t, c->reg.t0 );
 229                  brw_MOV(p, c->reg.t0, c->reg.t);
 230                  brw_set_predicate_control(p, BRW_PREDICATE_NONE);
 231              }
 232
 233              if (brw->has_negative_rhw_bug) {
 234                  brw_ENDIF(p, is_neg2);
 235              }
 236          }
 237          brw_ENDIF(p, is_negative);
 238       }
 239       brw_ENDIF(p, plane_active);
 240
 241       /* plane_ptr++;
 242        */
 243       brw_ADD(p, get_addr_reg(plane_ptr), get_addr_reg(plane_ptr), brw_clip_plane_stride(c));
 244
 245       /* while (planemask>>=1) != 0
 246        */
 247       brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 248       brw_SHR(p, c->reg.planemask, c->reg.planemask, brw_imm_ud(1));
 249    }
 250    brw_WHILE(p, plane_loop);
 251
 252    brw_ADD(p, c->reg.t, c->reg.t0, c->reg.t1);
 253    brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_L, c->reg.t, brw_imm_f(1.0));
 254    not_culled = brw_IF(p, BRW_EXECUTE_1);
 255    {
 256       brw_clip_interp_vertex(c, newvtx0, vtx0, vtx1, c->reg.t0, GL_FALSE);
 257       brw_clip_interp_vertex(c, newvtx1, vtx1, vtx0, c->reg.t1, GL_FALSE);
 258
 259       brw_clip_emit_vue(c, newvtx0, 1, 0, (_3DPRIM_LINESTRIP << 2) | R02_PRIM_START);
 260       brw_clip_emit_vue(c, newvtx1, 0, 1, (_3DPRIM_LINESTRIP << 2) | R02_PRIM_END);
 261    }
 262    brw_ENDIF(p, not_culled);
 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 }