src/gallium/drivers/i965simple/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 "brw_defines.h"
  33 #include "brw_context.h"
  34 #include "brw_eu.h"
  35 #include "brw_util.h"
  36 #include "brw_clip.h"
  37
  38
  39
  40 static void brw_clip_line_alloc_regs( struct brw_clip_compile *c )
  41 {
  42    unsigned i = 0,j;
  43
  44    /* Register usage is static, precompute here:
  45     */
  46    c->reg.R0 = retype(brw_vec8_grf(i, 0), BRW_REGISTER_TYPE_UD); i++;
  47
  48    if (c->key.nr_userclip) {
  49       c->reg.fixed_planes = brw_vec4_grf(i, 0);
  50       i += (6 + c->key.nr_userclip + 1) / 2;
  51
  52       c->prog_data.curb_read_length = (6 + c->key.nr_userclip + 1) / 2;
  53    }
  54    else
  55       c->prog_data.curb_read_length = 0;
  56
  57
  58    /* Payload vertices plus space for more generated vertices:
  59     */
  60    for (j = 0; j < 4; j++) {
  61       c->reg.vertex[j] = brw_vec4_grf(i, 0);
  62       i += c->nr_regs;
  63    }
  64
  65    c->reg.t           = brw_vec1_grf(i, 0);
  66    c->reg.t0          = brw_vec1_grf(i, 1);
  67    c->reg.t1          = brw_vec1_grf(i, 2);
  68    c->reg.planemask   = retype(brw_vec1_grf(i, 3), BRW_REGISTER_TYPE_UD);
  69    c->reg.plane_equation = brw_vec4_grf(i, 4);
  70    i++;
  71
  72    c->reg.dp0         = brw_vec1_grf(i, 0); /* fixme - dp4 will clobber r.1,2,3 */
  73    c->reg.dp1         = brw_vec1_grf(i, 4);
  74    i++;
  75
  76    if (!c->key.nr_userclip) {
  77       c->reg.fixed_planes = brw_vec8_grf(i, 0);
  78       i++;
  79    }
  80
  81
  82    c->first_tmp = i;
  83    c->last_tmp = i;
  84
  85    c->prog_data.urb_read_length = c->nr_regs; /* ? */
  86    c->prog_data.total_grf = i;
  87 }
  88
  89
  90
  91 /* Line clipping, more or less following the following algorithm:
  92  *
  93  *  for (p=0;p<MAX_PLANES;p++) {
  94  *     if (clipmask & (1 << p)) {
  95  *        float dp0 = DOTPROD( vtx0, plane[p] );
  96  *        float dp1 = DOTPROD( vtx1, plane[p] );
  97  *
  98  *        if (IS_NEGATIVE(dp1)) {
  99  *           float t = dp1 / (dp1 - dp0);
 100  *           if (t > t1) t1 = t;
 101  *        } else {
 102  *           float t = dp0 / (dp0 - dp1);
 103  *           if (t > t0) t0 = t;
 104  *        }
 105  *
 106  *        if (t0 + t1 >= 1.0)
 107  *           return;
 108  *     }
 109  *  }
 110  *
 111  *  interp( ctx, newvtx0, vtx0, vtx1, t0 );
 112  *  interp( ctx, newvtx1, vtx1, vtx0, t1 );
 113  *
 114  */
 115 static void clip_and_emit_line( struct brw_clip_compile *c )
 116 {
 117    struct brw_compile *p = &c->func;
 118    struct brw_indirect vtx0     = brw_indirect(0, 0);
 119    struct brw_indirect vtx1      = brw_indirect(1, 0);
 120    struct brw_indirect newvtx0   = brw_indirect(2, 0);
 121    struct brw_indirect newvtx1   = brw_indirect(3, 0);
 122    struct brw_indirect plane_ptr = brw_indirect(4, 0);
 123    struct brw_instruction *plane_loop;
 124    struct brw_instruction *plane_active;
 125    struct brw_instruction *is_negative;
 126    struct brw_instruction *is_neg2;
 127    struct brw_instruction *not_culled;
 128    struct brw_reg v1_null_ud = retype(vec1(brw_null_reg()), BRW_REGISTER_TYPE_UD);
 129
 130    brw_MOV(p, get_addr_reg(vtx0),      brw_address(c->reg.vertex[0]));
 131    brw_MOV(p, get_addr_reg(vtx1),      brw_address(c->reg.vertex[1]));
 132    brw_MOV(p, get_addr_reg(newvtx0),   brw_address(c->reg.vertex[2]));
 133    brw_MOV(p, get_addr_reg(newvtx1),   brw_address(c->reg.vertex[3]));
 134    brw_MOV(p, get_addr_reg(plane_ptr), brw_clip_plane0_address(c));
 135
 136    /* Note: init t0, t1 together:
 137     */
 138    brw_MOV(p, vec2(c->reg.t0), brw_imm_f(0));
 139
 140    brw_clip_init_planes(c);
 141    brw_clip_init_clipmask(c);
 142
 143    /* -ve rhw workaround */
 144    brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 145    brw_AND(p, brw_null_reg(), get_element_ud(c->reg.R0, 2),
 146            brw_imm_ud(1<<20));
 147    brw_OR(p, c->reg.planemask, c->reg.planemask, brw_imm_ud(0x3f));
 148    brw_set_predicate_control(p, BRW_PREDICATE_NONE);
 149
 150    plane_loop = brw_DO(p, BRW_EXECUTE_1);
 151    {
 152       /* if (planemask & 1)
 153        */
 154       brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 155       brw_AND(p, v1_null_ud, c->reg.planemask, brw_imm_ud(1));
 156
 157       plane_active = brw_IF(p, BRW_EXECUTE_1);
 158       {
 159          if (c->key.nr_userclip)
 160             brw_MOV(p, c->reg.plane_equation, deref_4f(plane_ptr, 0));
 161          else
 162             brw_MOV(p, c->reg.plane_equation, deref_4b(plane_ptr, 0));
 163
 164 #if 0
 165          /* dp = DP4(vtx->position, plane)
 166           */
 167          brw_DP4(p, vec4(c->reg.dp0), deref_4f(vtx0, c->offset[VERT_RESULT_HPOS]), c->reg.plane_equation);
 168
 169          /* if (IS_NEGATIVE(dp1))
 170           */
 171          brw_set_conditionalmod(p, BRW_CONDITIONAL_L);
 172          brw_DP4(p, vec4(c->reg.dp1), deref_4f(vtx1, c->offset[VERT_RESULT_HPOS]), c->reg.plane_equation);
 173 #else
 174          #warning "disabled"
 175 #endif
 176          is_negative = brw_IF(p, BRW_EXECUTE_1);
 177          {
 178             brw_ADD(p, c->reg.t, c->reg.dp1, negate(c->reg.dp0));
 179             brw_math_invert(p, c->reg.t, c->reg.t);
 180             brw_MUL(p, c->reg.t, c->reg.t, c->reg.dp1);
 181
 182             brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_G, c->reg.t, c->reg.t1 );
 183             brw_MOV(p, c->reg.t1, c->reg.t);
 184             brw_set_predicate_control(p, BRW_PREDICATE_NONE);
 185          }
 186          is_negative = brw_ELSE(p, is_negative);
 187          {
 188             /* Coming back in.  We know that both cannot be negative
 189              * because the line would have been culled in that case.
 190              */
 191
 192             /* If both are positive, do nothing */
 193              brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_L, c->reg.dp0, brw_imm_f(0.0));
 194              is_neg2 = brw_IF(p, BRW_EXECUTE_1);
 195              {
 196                 brw_ADD(p, c->reg.t, c->reg.dp0, negate(c->reg.dp1));
 197                 brw_math_invert(p, c->reg.t, c->reg.t);
 198                 brw_MUL(p, c->reg.t, c->reg.t, c->reg.dp0);
 199
 200                 brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_G, c->reg.t, c->reg.t0 );
 201                 brw_MOV(p, c->reg.t0, c->reg.t);
 202                 brw_set_predicate_control(p, BRW_PREDICATE_NONE);
 203              }
 204              brw_ENDIF(p, is_neg2);
 205          }
 206          brw_ENDIF(p, is_negative);
 207       }
 208       brw_ENDIF(p, plane_active);
 209
 210       /* plane_ptr++;
 211        */
 212       brw_ADD(p, get_addr_reg(plane_ptr), get_addr_reg(plane_ptr), brw_clip_plane_stride(c));
 213
 214       /* while (planemask>>=1) != 0
 215        */
 216       brw_set_conditionalmod(p, BRW_CONDITIONAL_NZ);
 217       brw_SHR(p, c->reg.planemask, c->reg.planemask, brw_imm_ud(1));
 218    }
 219    brw_WHILE(p, plane_loop);
 220
 221    brw_ADD(p, c->reg.t, c->reg.t0, c->reg.t1);
 222    brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_L, c->reg.t, brw_imm_f(1.0));
 223    not_culled = brw_IF(p, BRW_EXECUTE_1);
 224    {
 225       brw_clip_interp_vertex(c, newvtx0, vtx0, vtx1, c->reg.t0, FALSE);
 226       brw_clip_interp_vertex(c, newvtx1, vtx1, vtx0, c->reg.t1, FALSE);
 227
 228       brw_clip_emit_vue(c, newvtx0, 1, 0, (_3DPRIM_LINESTRIP << 2) | R02_PRIM_START);
 229       brw_clip_emit_vue(c, newvtx1, 0, 1, (_3DPRIM_LINESTRIP << 2) | R02_PRIM_END);
 230    }
 231    brw_ENDIF(p, not_culled);
 232    brw_clip_kill_thread(c);
 233 }
 234
 235
 236
 237 void brw_emit_line_clip( struct brw_clip_compile *c )
 238 {
 239    brw_clip_line_alloc_regs(c);
 240
 241    if (c->key.do_flat_shading)
 242       brw_clip_copy_colors(c, 0, 1);
 243
 244    clip_and_emit_line(c);
 245 }