sp_quad_earlyz.c

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/**************************************************************************
 * 
 * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
 * All Rights Reserved.
 * 
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 * 
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 * 
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 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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#include "pipe/p_defines.h"
#include "util/u_memory.h"
#include "sp_headers.h"
#include "sp_quad.h"


static void
earlyz_quad(
   struct quad_stage    *qs,
   struct quad_header   *quad )
{
   const float fx = (float) quad->input.x0;
   const float fy = (float) quad->input.y0;
   const float dzdx = quad->posCoef->dadx[2];
   const float dzdy = quad->posCoef->dady[2];
   const float z0 = quad->posCoef->a0[2] + dzdx * fx + dzdy * fy;

   quad->output.depth[0] = z0;
   quad->output.depth[1] = z0 + dzdx;
   quad->output.depth[2] = z0 + dzdy;
   quad->output.depth[3] = z0 + dzdx + dzdy;

   qs->next->run( qs->next, quad );
}

static void
earlyz_begin(
   struct quad_stage *qs )
{
   qs->next->begin( qs->next );
}

static void
earlyz_destroy(
   struct quad_stage *qs )
{
   FREE( qs );
}

struct quad_stage *
sp_quad_earlyz_stage(
   struct softpipe_context *softpipe )
{
   struct quad_stage *stage = CALLOC_STRUCT( quad_stage );

   stage->softpipe = softpipe;
   stage->begin = earlyz_begin;
   stage->run = earlyz_quad;
   stage->destroy = earlyz_destroy;

   return stage;
}

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