xref: /xsrc/external/mit/MesaLib/dist/src/mesa/main/depth.c

/*
 * Mesa 3-D graphics library
 * Version:  6.5
 *
 * Copyright (C) 1999-2005  Brian Paul   All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */


#include "glheader.h"
#include "imports.h"
#include "context.h"
#include "depth.h"
#include "enums.h"
#include "hash.h"
#include "macros.h"
#include "mtypes.h"


/**********************************************************************/
/*****                          API Functions                     *****/
/**********************************************************************/



void GLAPIENTRY
_mesa_ClearDepth( GLclampd depth )
{
   GET_CURRENT_CONTEXT(ctx);
   ASSERT_OUTSIDE_BEGIN_END(ctx);

   depth = CLAMP( depth, 0.0, 1.0 );

   if (ctx->Depth.Clear == depth)
      return;

   FLUSH_VERTICES(ctx, _NEW_DEPTH);
   ctx->Depth.Clear = depth;
   if (ctx->Driver.ClearDepth)
      (*ctx->Driver.ClearDepth)( ctx, ctx->Depth.Clear );
}



void GLAPIENTRY
_mesa_DepthFunc( GLenum func )
{
   GET_CURRENT_CONTEXT(ctx);
   ASSERT_OUTSIDE_BEGIN_END(ctx);

   if (MESA_VERBOSE & (VERBOSE_API|VERBOSE_TEXTURE))
      _mesa_debug(ctx, "glDepthFunc %s\n", _mesa_lookup_enum_by_nr(func));

   switch (func) {
   case GL_LESS:    /* (default) pass if incoming z < stored z */
   case GL_GEQUAL:
   case GL_LEQUAL:
   case GL_GREATER:
   case GL_NOTEQUAL:
   case GL_EQUAL:
   case GL_ALWAYS:
   case GL_NEVER:
      break;
   default:
      _mesa_error( ctx, GL_INVALID_ENUM, "glDepth.Func" );
      return;
   }

   if (ctx->Depth.Func == func)
      return;

   FLUSH_VERTICES(ctx, _NEW_DEPTH);
   ctx->Depth.Func = func;

   if (ctx->Driver.DepthFunc)
      ctx->Driver.DepthFunc( ctx, func );
}



void GLAPIENTRY
_mesa_DepthMask( GLboolean flag )
{
   GET_CURRENT_CONTEXT(ctx);
   ASSERT_OUTSIDE_BEGIN_END(ctx);

   if (MESA_VERBOSE & (VERBOSE_API|VERBOSE_TEXTURE))
      _mesa_debug(ctx, "glDepthMask %d\n", flag);

   /*
    * GL_TRUE indicates depth buffer writing is enabled (default)
    * GL_FALSE indicates depth buffer writing is disabled
    */
   if (ctx->Depth.Mask == flag)
      return;

   FLUSH_VERTICES(ctx, _NEW_DEPTH);
   ctx->Depth.Mask = flag;

   if (ctx->Driver.DepthMask)
      ctx->Driver.DepthMask( ctx, flag );
}



/**
 * Specified by the GL_EXT_depth_bounds_test extension.
 */
void GLAPIENTRY
_mesa_DepthBoundsEXT( GLclampd zmin, GLclampd zmax )
{
   GET_CURRENT_CONTEXT(ctx);
   ASSERT_OUTSIDE_BEGIN_END(ctx);

   if (zmin > zmax) {
      _mesa_error(ctx, GL_INVALID_VALUE, "glDepthBoundsEXT(zmin > zmax)");
      return;
   }

   zmin = CLAMP(zmin, 0.0, 1.0);
   zmax = CLAMP(zmax, 0.0, 1.0);

   if (ctx->Depth.BoundsMin == zmin && ctx->Depth.BoundsMax == zmax)
      return;

   FLUSH_VERTICES(ctx, _NEW_DEPTH);
   ctx->Depth.BoundsMin = (GLfloat) zmin;
   ctx->Depth.BoundsMax = (GLfloat) zmax;
}


/**********************************************************************/
/*****                      Initialization                        *****/
/**********************************************************************/


/**
 * Initialize the depth buffer attribute group in the given context.
 */
void _mesa_init_depth( GLcontext * ctx )
{
   /* Depth buffer group */
   ctx->Depth.Test = GL_FALSE;
   ctx->Depth.Clear = 1.0;
   ctx->Depth.Func = GL_LESS;
   ctx->Depth.Mask = GL_TRUE;

   /* XXX this is now per-framebuffer state */
#if 00
   /* Z buffer stuff */
   if (ctx->Visual.depthBits == 0) {
      /* Special case.  Even if we don't have a depth buffer we need
       * good values for DepthMax for Z vertex transformation purposes
       * and for per-fragment fog computation.
       */
      ctx->DepthMax = (1 << 16) - 1;
      ctx->DepthMaxF = (GLfloat) ctx->DepthMax;
   }
   else if (ctx->Visual.depthBits < 32) {
      ctx->DepthMax = (1 << ctx->Visual.depthBits) - 1;
      ctx->DepthMaxF = (GLfloat) ctx->DepthMax;
   }
   else {
      /* Special case since shift values greater than or equal to the
       * number of bits in the left hand expression's type are undefined.
       */
      ctx->DepthMax = 0xffffffff;
      ctx->DepthMaxF = (GLfloat) ctx->DepthMax;
   }
   ctx->MRD = 1.0;  /* Minimum resolvable depth value, for polygon offset */
#endif
}