mesa/swrast/s_context.c

/*
 * Mesa 3-D graphics library
 * Version:  6.1
 *
 * Copyright (C) 1999-2004  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.
 *
 * Authors:
 *    Keith Whitwell <keith@tungstengraphics.com>
 *    Brian Paul
 */

#include "imports.h"
#include "bufferobj.h"
#include "context.h"
#include "colormac.h"
#include "mtypes.h"
#include "program.h"
#include "texobj.h"
#include "nvfragprog.h"

#include "swrast.h"
#include "s_blend.h"
#include "s_context.h"
#include "s_lines.h"
#include "s_points.h"
#include "s_span.h"
#include "s_triangle.h"
#include "s_texture.h"


/**
 * Recompute the value of swrast->_RasterMask, etc. according to
 * the current context.  The _RasterMask field can be easily tested by
 * drivers to determine certain basic GL state (does the primitive need
 * stenciling, logic-op, fog, etc?).
 */
static void
_swrast_update_rasterflags( GLcontext *ctx )
{
   GLuint rasterMask = 0;

   if (ctx->Color.AlphaEnabled)           rasterMask |= ALPHATEST_BIT;
   if (ctx->Color.BlendEnabled)           rasterMask |= BLEND_BIT;
   if (ctx->Depth.Test)                   rasterMask |= DEPTH_BIT;
   if (ctx->Fog.Enabled)                  rasterMask |= FOG_BIT;
   if (ctx->Scissor.Enabled)              rasterMask |= CLIP_BIT;
   if (ctx->Stencil.Enabled)              rasterMask |= STENCIL_BIT;
   if (ctx->Visual.rgbMode) {
      const GLuint colorMask = *((GLuint *) &ctx->Color.ColorMask);
      if (colorMask != 0xffffffff)        rasterMask |= MASKING_BIT;
      if (ctx->Color._LogicOpEnabled)     rasterMask |= LOGIC_OP_BIT;
      if (ctx->Texture._EnabledUnits)     rasterMask |= TEXTURE_BIT;
   }
   else {
      if (ctx->Color.IndexMask != 0xffffffff) rasterMask |= MASKING_BIT;
      if (ctx->Color.IndexLogicOpEnabled)     rasterMask |= LOGIC_OP_BIT;
   }

   if (ctx->DrawBuffer->UseSoftwareAlphaBuffers
       && ctx->Color.ColorMask[ACOMP]
       && ctx->Color.DrawBuffer != GL_NONE)
      rasterMask |= ALPHABUF_BIT;

   if (   ctx->Viewport.X < 0
       || ctx->Viewport.X + ctx->Viewport.Width > (GLint) ctx->DrawBuffer->Width
       || ctx->Viewport.Y < 0
       || ctx->Viewport.Y + ctx->Viewport.Height > (GLint) ctx->DrawBuffer->Height) {
      rasterMask |= CLIP_BIT;
   }

   if (ctx->Depth.OcclusionTest || ctx->Occlusion.Active)
      rasterMask |= OCCLUSION_BIT;


   /* If we're not drawing to exactly one color buffer set the
    * MULTI_DRAW_BIT flag.  Also set it if we're drawing to no
    * buffers or the RGBA or CI mask disables all writes.
    */
   if (_mesa_bitcount(ctx->Color._DrawDestMask) != 1) {
      /* more than one color buffer designated for writing (or zero buffers) */
      rasterMask |= MULTI_DRAW_BIT;
   }
   else if (ctx->Visual.rgbMode && *((GLuint *) ctx->Color.ColorMask) == 0) {
      rasterMask |= MULTI_DRAW_BIT; /* all RGBA channels disabled */
   }
   else if (!ctx->Visual.rgbMode && ctx->Color.IndexMask==0) {
      rasterMask |= MULTI_DRAW_BIT; /* all color index bits disabled */
   }

   if (ctx->FragmentProgram._Enabled) {
      rasterMask |= FRAGPROG_BIT;
   }

   SWRAST_CONTEXT(ctx)->_RasterMask = rasterMask;
}


/**
 * Examine polycon culls tate to compute the _BackfaceSign field.
 * _BackfaceSign will be 0 if no culling, -1 if culling back-faces,
 * and 1 if culling front-faces.  The Polygon FrontFace state also
 * factors in.
 */
static void
_swrast_update_polygon( GLcontext *ctx )
{
   GLfloat backface_sign = 1;

   if (ctx->Polygon.CullFlag) {
      backface_sign = 1;
      switch(ctx->Polygon.CullFaceMode) {
      case GL_BACK:
	 if(ctx->Polygon.FrontFace==GL_CCW)
	    backface_sign = -1;
	 break;
      case GL_FRONT:
	 if(ctx->Polygon.FrontFace!=GL_CCW)
	    backface_sign = -1;
	 break;
      default:
      case GL_FRONT_AND_BACK:
	 backface_sign = 0;
	 break;
      }
   }
   else {
      backface_sign = 0;
   }

   SWRAST_CONTEXT(ctx)->_BackfaceSign = backface_sign;
}


/**
 * Update the _PreferPixelFog field to indicate if we need to compute
 * fog factors per-fragment.
 */
static void
_swrast_update_fog_hint( GLcontext *ctx )
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);
   swrast->_PreferPixelFog = (!swrast->AllowVertexFog ||
                              ctx->FragmentProgram._Enabled ||
			      (ctx->Hint.Fog == GL_NICEST &&
			       swrast->AllowPixelFog));
}


/**
 * Update the swrast->_AnyTextureCombine flag.
 */
static void
_swrast_update_texture_env( GLcontext *ctx )
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);
   GLuint i;
   swrast->_AnyTextureCombine = GL_FALSE;
   for (i = 0; i < ctx->Const.MaxTextureUnits; i++) {
      if (ctx->Texture.Unit[i].EnvMode == GL_COMBINE_EXT ||
          ctx->Texture.Unit[i].EnvMode == GL_COMBINE4_NV) {
         swrast->_AnyTextureCombine = GL_TRUE;
         return;
      }
   }
}


/**
 * Update swrast->_FogColor and swrast->_FogEnable values.
 */
static void
_swrast_update_fog_state( GLcontext *ctx )
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);

   /* convert fog color to GLchan values */
   CLAMPED_FLOAT_TO_CHAN(swrast->_FogColor[RCOMP], ctx->Fog.Color[RCOMP]);
   CLAMPED_FLOAT_TO_CHAN(swrast->_FogColor[GCOMP], ctx->Fog.Color[GCOMP]);
   CLAMPED_FLOAT_TO_CHAN(swrast->_FogColor[BCOMP], ctx->Fog.Color[BCOMP]);

   /* determine if fog is needed */
   swrast->_FogEnabled = GL_FALSE;
   if (ctx->Fog.Enabled) {
      swrast->_FogEnabled = GL_TRUE;
   }
   else if (ctx->FragmentProgram._Enabled &&
        ctx->FragmentProgram.Current->Base.Target == GL_FRAGMENT_PROGRAM_ARB) {
      const struct fragment_program *p;
      p = (struct fragment_program *) ctx->FragmentProgram.Current;
      if (p->FogOption != GL_NONE) {
         swrast->_FogEnabled = GL_TRUE;
      }
   }
}


/**
 * Update state for running fragment programs.  Basically, load the
 * program parameters with current state values.
 */
static void
_swrast_update_fragment_program( GLcontext *ctx )
{
   if (ctx->FragmentProgram._Enabled) {
      struct fragment_program *program = ctx->FragmentProgram.Current;
      _mesa_load_state_parameters(ctx, program->Parameters);
   }
}


#define _SWRAST_NEW_DERIVED (_SWRAST_NEW_RASTERMASK |	\
			     _NEW_TEXTURE |		\
			     _NEW_HINT |		\
			     _NEW_POLYGON )

/* State referenced by _swrast_choose_triangle, _swrast_choose_line.
 */
#define _SWRAST_NEW_TRIANGLE (_SWRAST_NEW_DERIVED |		\
			      _NEW_RENDERMODE|			\
                              _NEW_POLYGON|			\
                              _NEW_DEPTH|			\
                              _NEW_STENCIL|			\
                              _NEW_COLOR|			\
                              _NEW_TEXTURE|			\
                              _SWRAST_NEW_RASTERMASK|		\
                              _NEW_LIGHT|			\
                              _NEW_FOG |			\
			      _DD_NEW_SEPARATE_SPECULAR)

#define _SWRAST_NEW_LINE (_SWRAST_NEW_DERIVED |		\
			  _NEW_RENDERMODE|		\
                          _NEW_LINE|			\
                          _NEW_TEXTURE|			\
                          _NEW_LIGHT|			\
                          _NEW_FOG|			\
                          _NEW_DEPTH |			\
                          _DD_NEW_SEPARATE_SPECULAR)

#define _SWRAST_NEW_POINT (_SWRAST_NEW_DERIVED |	\
			   _NEW_RENDERMODE |		\
			   _NEW_POINT |			\
			   _NEW_TEXTURE |		\
			   _NEW_LIGHT |			\
			   _NEW_FOG |			\
                           _DD_NEW_SEPARATE_SPECULAR)

#define _SWRAST_NEW_TEXTURE_SAMPLE_FUNC _NEW_TEXTURE

#define _SWRAST_NEW_TEXTURE_ENV_MODE _NEW_TEXTURE

#define _SWRAST_NEW_BLEND_FUNC _NEW_COLOR


/**
 * Stub for swrast->Triangle to select a true triangle function
 * after a state change.
 */
static void
_swrast_validate_triangle( GLcontext *ctx,
			   const SWvertex *v0,
                           const SWvertex *v1,
                           const SWvertex *v2 )
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);

   _swrast_validate_derived( ctx );
   swrast->choose_triangle( ctx );

   if (ctx->Texture._EnabledUnits == 0
       && NEED_SECONDARY_COLOR(ctx)
       && !ctx->FragmentProgram._Enabled) {
      /* separate specular color, but no texture */
      swrast->SpecTriangle = swrast->Triangle;
      swrast->Triangle = _swrast_add_spec_terms_triangle;
   }

   swrast->Triangle( ctx, v0, v1, v2 );
}

/**
 * Called via swrast->Line.  Examine current GL state and choose a software
 * line routine.  Then call it.
 */
static void
_swrast_validate_line( GLcontext *ctx, const SWvertex *v0, const SWvertex *v1 )
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);

   _swrast_validate_derived( ctx );
   swrast->choose_line( ctx );

   if (ctx->Texture._EnabledUnits == 0
       && NEED_SECONDARY_COLOR(ctx)
       && !ctx->FragmentProgram._Enabled) {
      swrast->SpecLine = swrast->Line;
      swrast->Line = _swrast_add_spec_terms_line;
   }


   swrast->Line( ctx, v0, v1 );
}

/**
 * Called via swrast->Point.  Examine current GL state and choose a software
 * point routine.  Then call it.
 */
static void
_swrast_validate_point( GLcontext *ctx, const SWvertex *v0 )
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);

   _swrast_validate_derived( ctx );
   swrast->choose_point( ctx );

   if (ctx->Texture._EnabledUnits == 0
       && NEED_SECONDARY_COLOR(ctx)
       && !ctx->FragmentProgram._Enabled) {
      swrast->SpecPoint = swrast->Point;
      swrast->Point = _swrast_add_spec_terms_point;
   }

   swrast->Point( ctx, v0 );
}


/**
 * Called via swrast->BlendFunc.  Examine GL state to choose a blending
 * function, then call it.
 */
static void _ASMAPI
_swrast_validate_blend_func( GLcontext *ctx, GLuint n,
			     const GLubyte mask[],
			     GLchan src[][4],
			     CONST GLchan dst[][4] )
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);

   _swrast_validate_derived( ctx );
   _swrast_choose_blend_func( ctx );

   swrast->BlendFunc( ctx, n, mask, src, dst );
}


/**
 * Called via the swrast->TextureSample[i] function pointer.
 * Basically, given a texture object, an array of texture coords
 * and an array of level-of-detail values, return an array of colors.
 * In this case, determine the correct texture sampling routine
 * (depending on filter mode, texture dimensions, etc) then call the
 * sampler routine.
 */
static void
_swrast_validate_texture_sample( GLcontext *ctx, GLuint texUnit,
				 const struct gl_texture_object *tObj,
				 GLuint n, const GLfloat texcoords[][4],
				 const GLfloat lambda[], GLchan rgba[][4] )
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);

   _swrast_validate_derived( ctx );

   /* Compute min/mag filter threshold */
   if (tObj && tObj->MinFilter != tObj->MagFilter) {
      if (tObj->MagFilter == GL_LINEAR
          && (tObj->MinFilter == GL_NEAREST_MIPMAP_NEAREST ||
              tObj->MinFilter == GL_NEAREST_MIPMAP_LINEAR)) {
         swrast->_MinMagThresh[texUnit] = 0.5F;
      }
      else {
         swrast->_MinMagThresh[texUnit] = 0.0F;
      }
   }

   swrast->TextureSample[texUnit] =
      _swrast_choose_texture_sample_func( ctx, tObj );

   swrast->TextureSample[texUnit]( ctx, texUnit, tObj, n, texcoords,
                                   lambda, rgba );
}


static void
_swrast_sleep( GLcontext *ctx, GLuint new_state )
{
   (void) ctx; (void) new_state;
}


static void
_swrast_invalidate_state( GLcontext *ctx, GLuint new_state )
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);
   GLuint i;

   swrast->NewState |= new_state;

   /* After 10 statechanges without any swrast functions being called,
    * put the module to sleep.
    */
   if (++swrast->StateChanges > 10) {
      swrast->InvalidateState = _swrast_sleep;
      swrast->NewState = ~0;
      new_state = ~0;
   }

   if (new_state & swrast->invalidate_triangle)
      swrast->Triangle = _swrast_validate_triangle;

   if (new_state & swrast->invalidate_line)
      swrast->Line = _swrast_validate_line;

   if (new_state & swrast->invalidate_point)
      swrast->Point = _swrast_validate_point;

   if (new_state & _SWRAST_NEW_BLEND_FUNC)
      swrast->BlendFunc = _swrast_validate_blend_func;

   if (new_state & _SWRAST_NEW_TEXTURE_SAMPLE_FUNC)
      for (i = 0 ; i < ctx->Const.MaxTextureUnits ; i++)
	 swrast->TextureSample[i] = _swrast_validate_texture_sample;

   /* Debug checks */
   if (ctx->Visual.rgbMode) {
      ASSERT(swrast->Driver.WriteRGBASpan);
      ASSERT(swrast->Driver.WriteRGBSpan);
      ASSERT(swrast->Driver.WriteMonoRGBASpan);
      ASSERT(swrast->Driver.WriteRGBAPixels);
      ASSERT(swrast->Driver.WriteMonoRGBAPixels);
      ASSERT(swrast->Driver.ReadRGBASpan);
      ASSERT(swrast->Driver.ReadRGBAPixels);
   }
   else {
      ASSERT(swrast->Driver.WriteCI32Span);
      ASSERT(swrast->Driver.WriteCI8Span);
      ASSERT(swrast->Driver.WriteMonoCISpan);
      ASSERT(swrast->Driver.WriteCI32Pixels);
      ASSERT(swrast->Driver.WriteMonoCIPixels);
      ASSERT(swrast->Driver.ReadCI32Span);
      ASSERT(swrast->Driver.ReadCI32Pixels);
   }
}


void
_swrast_validate_derived( GLcontext *ctx )
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);

   if (swrast->NewState) {
      if (swrast->NewState & _SWRAST_NEW_RASTERMASK)
 	 _swrast_update_rasterflags( ctx );

      if (swrast->NewState & _NEW_POLYGON)
	 _swrast_update_polygon( ctx );

      if (swrast->NewState & (_NEW_HINT | _NEW_PROGRAM))
	 _swrast_update_fog_hint( ctx );

      if (swrast->NewState & _SWRAST_NEW_TEXTURE_ENV_MODE)
	 _swrast_update_texture_env( ctx );

      if (swrast->NewState & _NEW_FOG)
         _swrast_update_fog_state( ctx );

      if (swrast->NewState & _NEW_PROGRAM)
	 _swrast_update_fragment_program( ctx );

      swrast->NewState = 0;
      swrast->StateChanges = 0;
      swrast->InvalidateState = _swrast_invalidate_state;
   }
}

#define SWRAST_DEBUG 0

/* Public entrypoints:  See also s_accum.c, s_bitmap.c, etc.
 */
void
_swrast_Quad( GLcontext *ctx,
	      const SWvertex *v0, const SWvertex *v1,
              const SWvertex *v2, const SWvertex *v3 )
{
   if (SWRAST_DEBUG) {
      _mesa_debug(ctx, "_swrast_Quad\n");
      _swrast_print_vertex( ctx, v0 );
      _swrast_print_vertex( ctx, v1 );
      _swrast_print_vertex( ctx, v2 );
      _swrast_print_vertex( ctx, v3 );
   }
   SWRAST_CONTEXT(ctx)->Triangle( ctx, v0, v1, v3 );
   SWRAST_CONTEXT(ctx)->Triangle( ctx, v1, v2, v3 );
}

void
_swrast_Triangle( GLcontext *ctx, const SWvertex *v0,
                  const SWvertex *v1, const SWvertex *v2 )
{
   if (SWRAST_DEBUG) {
      _mesa_debug(ctx, "_swrast_Triangle\n");
      _swrast_print_vertex( ctx, v0 );
      _swrast_print_vertex( ctx, v1 );
      _swrast_print_vertex( ctx, v2 );
   }
   SWRAST_CONTEXT(ctx)->Triangle( ctx, v0, v1, v2 );
}

void
_swrast_Line( GLcontext *ctx, const SWvertex *v0, const SWvertex *v1 )
{
   if (SWRAST_DEBUG) {
      _mesa_debug(ctx, "_swrast_Line\n");
      _swrast_print_vertex( ctx, v0 );
      _swrast_print_vertex( ctx, v1 );
   }
   SWRAST_CONTEXT(ctx)->Line( ctx, v0, v1 );
}

void
_swrast_Point( GLcontext *ctx, const SWvertex *v0 )
{
   if (SWRAST_DEBUG) {
      _mesa_debug(ctx, "_swrast_Point\n");
      _swrast_print_vertex( ctx, v0 );
   }
   SWRAST_CONTEXT(ctx)->Point( ctx, v0 );
}

void
_swrast_InvalidateState( GLcontext *ctx, GLuint new_state )
{
   if (SWRAST_DEBUG) {
      _mesa_debug(ctx, "_swrast_InvalidateState\n");
   }
   SWRAST_CONTEXT(ctx)->InvalidateState( ctx, new_state );
}

void
_swrast_ResetLineStipple( GLcontext *ctx )
{
   if (SWRAST_DEBUG) {
      _mesa_debug(ctx, "_swrast_ResetLineStipple\n");
   }
   SWRAST_CONTEXT(ctx)->StippleCounter = 0;
}

void
_swrast_allow_vertex_fog( GLcontext *ctx, GLboolean value )
{
   if (SWRAST_DEBUG) {
      _mesa_debug(ctx, "_swrast_allow_vertex_fog %d\n", value);
   }
   SWRAST_CONTEXT(ctx)->InvalidateState( ctx, _NEW_HINT );
   SWRAST_CONTEXT(ctx)->AllowVertexFog = value;
}

void
_swrast_allow_pixel_fog( GLcontext *ctx, GLboolean value )
{
   if (SWRAST_DEBUG) {
      _mesa_debug(ctx, "_swrast_allow_pixel_fog %d\n", value);
   }
   SWRAST_CONTEXT(ctx)->InvalidateState( ctx, _NEW_HINT );
   SWRAST_CONTEXT(ctx)->AllowPixelFog = value;
}


GLboolean
_swrast_CreateContext( GLcontext *ctx )
{
   GLuint i;
   SWcontext *swrast = (SWcontext *)CALLOC(sizeof(SWcontext));

   if (SWRAST_DEBUG) {
      _mesa_debug(ctx, "_swrast_CreateContext\n");
   }

   if (!swrast)
      return GL_FALSE;

   swrast->NewState = ~0;

   swrast->choose_point = _swrast_choose_point;
   swrast->choose_line = _swrast_choose_line;
   swrast->choose_triangle = _swrast_choose_triangle;

   swrast->invalidate_point = _SWRAST_NEW_POINT;
   swrast->invalidate_line = _SWRAST_NEW_LINE;
   swrast->invalidate_triangle = _SWRAST_NEW_TRIANGLE;

   swrast->Point = _swrast_validate_point;
   swrast->Line = _swrast_validate_line;
   swrast->Triangle = _swrast_validate_triangle;
   swrast->InvalidateState = _swrast_sleep;
   swrast->BlendFunc = _swrast_validate_blend_func;

   swrast->AllowVertexFog = GL_TRUE;
   swrast->AllowPixelFog = GL_TRUE;

   if (ctx->Visual.doubleBufferMode)
      swrast->CurrentBufferBit = DD_BACK_LEFT_BIT;
   else
      swrast->CurrentBufferBit = DD_FRONT_LEFT_BIT;

   /* Optimized Accum buffer */
   swrast->_IntegerAccumMode = GL_TRUE;
   swrast->_IntegerAccumScaler = 0.0;

   for (i = 0; i < MAX_TEXTURE_IMAGE_UNITS; i++)
      swrast->TextureSample[i] = _swrast_validate_texture_sample;

   swrast->SpanArrays = MALLOC_STRUCT(span_arrays);
   if (!swrast->SpanArrays) {
      FREE(swrast);
      return GL_FALSE;
   }

   /* init point span buffer */
   swrast->PointSpan.primitive = GL_POINT;
   swrast->PointSpan.start = 0;
   swrast->PointSpan.end = 0;
   swrast->PointSpan.facing = 0;
   swrast->PointSpan.array = swrast->SpanArrays;

   assert(ctx->Const.MaxTextureUnits > 0);
   assert(ctx->Const.MaxTextureUnits <= MAX_TEXTURE_UNITS);

   swrast->TexelBuffer = (GLchan *) MALLOC(ctx->Const.MaxTextureUnits *
                                           MAX_WIDTH * 4 * sizeof(GLchan));
   if (!swrast->TexelBuffer) {
      FREE(swrast->SpanArrays);
      FREE(swrast);
      return GL_FALSE;
   }

   ctx->swrast_context = swrast;

   return GL_TRUE;
}

void
_swrast_DestroyContext( GLcontext *ctx )
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);

   if (SWRAST_DEBUG) {
      _mesa_debug(ctx, "_swrast_DestroyContext\n");
   }

   FREE( swrast->SpanArrays );
   FREE( swrast->TexelBuffer );
   FREE( swrast );

   ctx->swrast_context = 0;
}


struct swrast_device_driver *
_swrast_GetDeviceDriverReference( GLcontext *ctx )
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);
   return &swrast->Driver;
}

void
_swrast_flush( GLcontext *ctx )
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);
   /* flush any pending fragments from rendering points */
   if (swrast->PointSpan.end > 0) {
      if (ctx->Visual.rgbMode) {
         if (ctx->Texture._EnabledCoordUnits)
            _swrast_write_texture_span(ctx, &(swrast->PointSpan));
         else
            _swrast_write_rgba_span(ctx, &(swrast->PointSpan));
      }
      else {
         _swrast_write_index_span(ctx, &(swrast->PointSpan));
      }
      swrast->PointSpan.end = 0;
   }
}

void
_swrast_render_primitive( GLcontext *ctx, GLenum prim )
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);
   if (swrast->Primitive == GL_POINTS && prim != GL_POINTS) {
      _swrast_flush(ctx);
   }
   swrast->Primitive = prim;
}


void
_swrast_render_start( GLcontext *ctx )
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);
   if (swrast->Driver.SpanRenderStart)
      swrast->Driver.SpanRenderStart( ctx );
   swrast->PointSpan.end = 0;
}

void
_swrast_render_finish( GLcontext *ctx )
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);
   if (swrast->Driver.SpanRenderFinish)
      swrast->Driver.SpanRenderFinish( ctx );

   _swrast_flush(ctx);
}


#define SWRAST_DEBUG_VERTICES 0

void
_swrast_print_vertex( GLcontext *ctx, const SWvertex *v )
{
   GLuint i;

   if (SWRAST_DEBUG_VERTICES) {
      _mesa_debug(ctx, "win %f %f %f %f\n",
                  v->win[0], v->win[1], v->win[2], v->win[3]);

      for (i = 0 ; i < ctx->Const.MaxTextureUnits ; i++)
	 if (ctx->Texture.Unit[i]._ReallyEnabled)
	    _mesa_debug(ctx, "texcoord[%d] %f %f %f %f\n", i,
                        v->texcoord[i][0], v->texcoord[i][1],
                        v->texcoord[i][2], v->texcoord[i][3]);

#if CHAN_TYPE == GL_FLOAT
      _mesa_debug(ctx, "color %f %f %f %f\n",
                  v->color[0], v->color[1], v->color[2], v->color[3]);
      _mesa_debug(ctx, "spec %f %f %f %f\n",
                  v->specular[0], v->specular[1],
                  v->specular[2], v->specular[3]);
#else
      _mesa_debug(ctx, "color %d %d %d %d\n",
                  v->color[0], v->color[1], v->color[2], v->color[3]);
      _mesa_debug(ctx, "spec %d %d %d %d\n",
                  v->specular[0], v->specular[1],
                  v->specular[2], v->specular[3]);
#endif
      _mesa_debug(ctx, "fog %f\n", v->fog);
      _mesa_debug(ctx, "index %d\n", v->index);
      _mesa_debug(ctx, "pointsize %f\n", v->pointSize);
      _mesa_debug(ctx, "\n");
   }
}


/**
 * Validate access to a PBO to be sure we're not going to read/write
 * out of buffer bounds.
 */
GLvoid *
_swrast_validate_pbo_access(const struct gl_pixelstore_attrib *pack,
                            GLsizei width, GLsizei height, GLsizei depth,
                            GLenum format, GLenum type, GLvoid *ptr)
{
   if (pack->BufferObj->Name == 0) {
      /* no PBO */
      return ptr;
   }
   else if (_mesa_validate_pbo_access(pack, width, height, depth, format,
                                      type, ptr)) {
      return ADD_POINTERS(pack->BufferObj->Data, ptr);
   }
   /* bad access! */
   return NULL;
}