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 "glheader.h"
  33 #include "macros.h"
  34 #include "enums.h"
  35
  36 #include "shader/program.h"
  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    brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 152    brw_AND(p, brw_null_reg(), get_element_ud(c->reg.R0, 2),
 153            brw_imm_ud(1<<20));
 154    brw_OR(p, c->reg.planemask, c->reg.planemask, brw_imm_ud(0x3f));
 155    brw_set_predicate_control(p, BRW_PREDICATE_NONE);
 156
 157    plane_loop = brw_DO(p, BRW_EXECUTE_1);
 158    {
 159       /* if (planemask & 1)
 160        */
 161       brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 162       brw_AND(p, v1_null_ud, c->reg.planemask, brw_imm_ud(1));
 163
 164       plane_active = brw_IF(p, BRW_EXECUTE_1);
 165       {
 166          if (c->key.nr_userclip)
 167             brw_MOV(p, c->reg.plane_equation, deref_4f(plane_ptr, 0));
 168          else
 169             brw_MOV(p, c->reg.plane_equation, deref_4b(plane_ptr, 0));
 170
 171          /* dp = DP4(vtx->position, plane)
 172           */
 173          brw_DP4(p, vec4(c->reg.dp0), deref_4f(vtx0, c->offset[VERT_RESULT_HPOS]), c->reg.plane_equation);
 174
 175          /* if (IS_NEGATIVE(dp1))
 176           */
 177          brw_set_conditionalmod(p, BRW_CONDITIONAL_L);
 178          brw_DP4(p, vec4(c->reg.dp1), deref_4f(vtx1, c->offset[VERT_RESULT_HPOS]), c->reg.plane_equation);
 179          is_negative = brw_IF(p, BRW_EXECUTE_1);
 180          {
 181             brw_ADD(p, c->reg.t, c->reg.dp1, negate(c->reg.dp0));
 182             brw_math_invert(p, c->reg.t, c->reg.t);
 183             brw_MUL(p, c->reg.t, c->reg.t, c->reg.dp1);
 184
 185             brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_G, c->reg.t, c->reg.t1 );
 186             brw_MOV(p, c->reg.t1, c->reg.t);
 187             brw_set_predicate_control(p, BRW_PREDICATE_NONE);
 188          }
 189          is_negative = brw_ELSE(p, is_negative);
 190          {
 191             /* Coming back in.  We know that both cannot be negative
 192              * because the line would have been culled in that case.
 193              */
 194
 195             /* If both are positive, do nothing */
 196              brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_L, c->reg.dp0, brw_imm_f(0.0));
 197              is_neg2 = brw_IF(p, BRW_EXECUTE_1);
 198              {
 199                 brw_ADD(p, c->reg.t, c->reg.dp0, negate(c->reg.dp1));
 200                 brw_math_invert(p, c->reg.t, c->reg.t);
 201                 brw_MUL(p, c->reg.t, c->reg.t, c->reg.dp0);
 202
 203                 brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_G, c->reg.t, c->reg.t0 );
 204                 brw_MOV(p, c->reg.t0, c->reg.t);
 205                 brw_set_predicate_control(p, BRW_PREDICATE_NONE);
 206              }
 207              brw_ENDIF(p, is_neg2);
 208          }
 209          brw_ENDIF(p, is_negative);
 210       }
 211       brw_ENDIF(p, plane_active);
 212
 213       /* plane_ptr++;
 214        */
 215       brw_ADD(p, get_addr_reg(plane_ptr), get_addr_reg(plane_ptr), brw_clip_plane_stride(c));
 216
 217       /* while (planemask>>=1) != 0
 218        */
 219       brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 220       brw_SHR(p, c->reg.planemask, c->reg.planemask, brw_imm_ud(1));
 221    }
 222    brw_WHILE(p, plane_loop);
 223
 224    brw_ADD(p, c->reg.t, c->reg.t0, c->reg.t1);
 225    brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_L, c->reg.t, brw_imm_f(1.0));
 226    not_culled = brw_IF(p, BRW_EXECUTE_1);
 227    {
 228       brw_clip_interp_vertex(c, newvtx0, vtx0, vtx1, c->reg.t0, GL_FALSE);
 229       brw_clip_interp_vertex(c, newvtx1, vtx1, vtx0, c->reg.t1, GL_FALSE);
 230
 231       brw_clip_emit_vue(c, newvtx0, 1, 0, (_3DPRIM_LINESTRIP << 2) | R02_PRIM_START);
 232       brw_clip_emit_vue(c, newvtx1, 0, 1, (_3DPRIM_LINESTRIP << 2) | R02_PRIM_END);
 233    }
 234    brw_ENDIF(p, not_culled);
 235    brw_clip_kill_thread(c);
 236 }
 237
 238
 239
 240 void brw_emit_line_clip( struct brw_clip_compile *c )
 241 {
 242    brw_clip_line_alloc_regs(c);
 243
 244    if (c->key.do_flat_shading)
 245       brw_clip_copy_colors(c, 0, 1);
 246
 247    clip_and_emit_line(c);
 248 }