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 *not_culled;
 134    struct brw_reg v1_null_ud = retype(vec1(brw_null_reg()), BRW_REGISTER_TYPE_UD);
 135
 136    brw_MOV(p, get_addr_reg(vtx0),      brw_address(c->reg.vertex[0]));
 137    brw_MOV(p, get_addr_reg(vtx1),      brw_address(c->reg.vertex[1]));
 138    brw_MOV(p, get_addr_reg(newvtx0),   brw_address(c->reg.vertex[2]));
 139    brw_MOV(p, get_addr_reg(newvtx1),   brw_address(c->reg.vertex[3]));
 140    brw_MOV(p, get_addr_reg(plane_ptr), brw_clip_plane0_address(c));
 141
 142    /* Note: init t0, t1 together:
 143     */
 144    brw_MOV(p, vec2(c->reg.t0), brw_imm_f(0));
 145
 146    brw_clip_init_planes(c);
 147    brw_clip_init_clipmask(c);
 148
 149    plane_loop = brw_DO(p, BRW_EXECUTE_1);
 150    {
 151       /* if (planemask & 1)
 152        */
 153       brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 154       brw_AND(p, v1_null_ud, c->reg.planemask, brw_imm_ud(1));
 155
 156       plane_active = brw_IF(p, BRW_EXECUTE_1);
 157       {
 158          if (c->key.nr_userclip)
 159             brw_MOV(p, c->reg.plane_equation, deref_4f(plane_ptr, 0));
 160          else
 161             brw_MOV(p, c->reg.plane_equation, deref_4b(plane_ptr, 0));
 162
 163          /* dp = DP4(vtx->position, plane)
 164           */
 165          brw_DP4(p, vec4(c->reg.dp0), deref_4f(vtx0, c->offset[VERT_RESULT_HPOS]), c->reg.plane_equation);
 166
 167          /* if (IS_NEGATIVE(dp1))
 168           */
 169          brw_set_conditionalmod(p, BRW_CONDITIONAL_L);
 170          brw_DP4(p, vec4(c->reg.dp1), deref_4f(vtx1, c->offset[VERT_RESULT_HPOS]), c->reg.plane_equation);
 171          is_negative = brw_IF(p, BRW_EXECUTE_1);
 172          {
 173             brw_ADD(p, c->reg.t, c->reg.dp1, negate(c->reg.dp0));
 174             brw_math_invert(p, c->reg.t, c->reg.t);
 175             brw_MUL(p, c->reg.t, c->reg.t, c->reg.dp1);
 176
 177             brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_G, c->reg.t, c->reg.t1 );
 178             brw_MOV(p, c->reg.t1, c->reg.t);
 179             brw_set_predicate_control(p, BRW_PREDICATE_NONE);
 180          }
 181          is_negative = brw_ELSE(p, is_negative);
 182          {
 183             /* Coming back in.  We know that both cannot be negative
 184              * because the line would have been culled in that case.
 185              */
 186             brw_ADD(p, c->reg.t, c->reg.dp0, negate(c->reg.dp1));
 187             brw_math_invert(p, c->reg.t, c->reg.t);
 188             brw_MUL(p, c->reg.t, c->reg.t, c->reg.dp0);
 189
 190             brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_G, c->reg.t, c->reg.t0 );
 191             brw_MOV(p, c->reg.t0, c->reg.t);
 192             brw_set_predicate_control(p, BRW_PREDICATE_NONE);
 193          }
 194          brw_ENDIF(p, is_negative);
 195       }
 196       brw_ENDIF(p, plane_active);
 197
 198       /* plane_ptr++;
 199        */
 200       brw_ADD(p, get_addr_reg(plane_ptr), get_addr_reg(plane_ptr), brw_clip_plane_stride(c));
 201
 202       /* while (planemask>>=1) != 0
 203        */
 204       brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 205       brw_SHR(p, c->reg.planemask, c->reg.planemask, brw_imm_ud(1));
 206    }
 207    brw_WHILE(p, plane_loop);
 208
 209    brw_ADD(p, c->reg.t, c->reg.t0, c->reg.t1);
 210    brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_L, c->reg.t, brw_imm_f(1.0));
 211    not_culled = brw_IF(p, BRW_EXECUTE_1);
 212    {
 213       brw_clip_interp_vertex(c, newvtx0, vtx0, vtx1, c->reg.t0, GL_FALSE);
 214       brw_clip_interp_vertex(c, newvtx1, vtx1, vtx0, c->reg.t1, GL_FALSE);
 215
 216       brw_clip_emit_vue(c, newvtx0, 1, 0, (_3DPRIM_LINESTRIP << 2) | R02_PRIM_START);
 217       brw_clip_emit_vue(c, newvtx1, 0, 1, (_3DPRIM_LINESTRIP << 2) | R02_PRIM_END);
 218    }
 219    brw_ENDIF(p, not_culled);
 220    brw_clip_kill_thread(c);
 221 }
 222
 223
 224
 225 void brw_emit_line_clip( struct brw_clip_compile *c )
 226 {
 227    brw_clip_line_alloc_regs(c);
 228
 229    if (c->key.do_flat_shading)
 230       brw_clip_copy_colors(c, 0, 1);
 231
 232    clip_and_emit_line(c);
 233 }