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
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  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.
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  24  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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  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   *quad )
  47 {
  48    const float fx = (float) quad->input.x0;
  49    const float fy = (float) quad->input.y0;
  50    const float dzdx = quad->posCoef->dadx[2];
  51    const float dzdy = quad->posCoef->dady[2];
  52    const float z0 = quad->posCoef->a0[2] + dzdx * fx + dzdy * fy;
  53
  54    quad->output.depth[0] = z0;
  55    quad->output.depth[1] = z0 + dzdx;
  56    quad->output.depth[2] = z0 + dzdy;
  57    quad->output.depth[3] = z0 + dzdx + dzdy;
  58
  59    qs->next->run( qs->next, quad );
  60 }
  61
  62 static void
  63 earlyz_begin(
  64    struct quad_stage *qs )
  65 {
  66    qs->next->begin( qs->next );
  67 }
  68
  69 static void
  70 earlyz_destroy(
  71    struct quad_stage *qs )
  72 {
  73    FREE( qs );
  74 }
  75
  76 struct quad_stage *
  77 sp_quad_earlyz_stage(
  78    struct softpipe_context *softpipe )
  79 {
  80    struct quad_stage *stage = CALLOC_STRUCT( quad_stage );
  81
  82    stage->softpipe = softpipe;
  83    stage->begin = earlyz_begin;
  84    stage->run = earlyz_quad;
  85    stage->destroy = earlyz_destroy;
  86
  87    return stage;
  88 }