src/gallium/drivers/softpipe/sp_quad_earlyz.c

   1 /**************************************************************************
   2  *
   3  * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
   4  * All Rights Reserved.
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a
   7  * 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, sub license, 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 portions
  16  * of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  19  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  20  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
  21  * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
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  24  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  25  *
  26  **************************************************************************/
  27
  28 /**
  29  * \brief  Quad early-z testing
  30  */
  31
  32 #include "pipe/p_defines.h"
  33 #include "util/u_memory.h"
  34 #include "sp_quad.h"
  35 #include "sp_quad_pipe.h"
  36
  37
  38 /**
  39  * All this stage does is compute the quad's Z values (which is normally
  40  * done by the shading stage).
  41  * The next stage will do the actual depth test.
  42  */
  43 static void
  44 earlyz_quad(
  45    struct quad_stage    *qs,
  46    struct quad_header   *quads[],
  47    unsigned nr )
  48 {
  49    const float a0z = quads[0]->posCoef->a0[2];
  50    const float dzdx = quads[0]->posCoef->dadx[2];
  51    const float dzdy = quads[0]->posCoef->dady[2];
  52    unsigned i;
  53
  54    for (i = 0; i < nr; i++) {
  55       const float fx = (float) quads[i]->input.x0;
  56       const float fy = (float) quads[i]->input.y0;
  57       const float z0 = a0z + dzdx * fx + dzdy * fy;
  58
  59       quads[i]->output.depth[0] = z0;
  60       quads[i]->output.depth[1] = z0 + dzdx;
  61       quads[i]->output.depth[2] = z0 + dzdy;
  62       quads[i]->output.depth[3] = z0 + dzdx + dzdy;
  63    }
  64
  65    qs->next->run( qs->next, quads, nr );
  66 }
  67
  68 static void
  69 earlyz_begin(
  70    struct quad_stage *qs )
  71 {
  72    qs->next->begin( qs->next );
  73 }
  74
  75 static void
  76 earlyz_destroy(
  77    struct quad_stage *qs )
  78 {
  79    FREE( qs );
  80 }
  81
  82 struct quad_stage *
  83 sp_quad_earlyz_stage(
  84    struct softpipe_context *softpipe )
  85 {
  86    struct quad_stage *stage = CALLOC_STRUCT( quad_stage );
  87
  88    stage->softpipe = softpipe;
  89    stage->begin = earlyz_begin;
  90    stage->run = earlyz_quad;
  91    stage->destroy = earlyz_destroy;
  92
  93    return stage;
  94 }