text: /**
   * \file polygon.c
   * Polygon operations.
   */
  
  /*
   * Mesa 3-D graphics library
   * Version:  6.3
   *
   * 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.
   */
  
  
  #include "glheader.h"
  #include "imports.h"
  #include "bufferobj.h"
  #include "context.h"
  #include "image.h"
  #include "enums.h"
  #include "macros.h"
  #include "polygon.h"
  #include "mtypes.h"
  
  
  /**
   * Specify whether to cull front- or back-facing facets.
   *
   * \param mode culling mode.
   *
   * \sa glCullFace().
   *
   * Verifies the parameter and updates gl_polygon_attrib::CullFaceMode. On
   * change, flushes the vertices and notifies the driver via
   * the dd_function_table::CullFace callback.
   */
  void GLAPIENTRY
  _mesa_CullFace( GLenum mode )
  {
     GET_CURRENT_CONTEXT(ctx);
     ASSERT_OUTSIDE_BEGIN_END(ctx);
  
     if (MESA_VERBOSE&VERBOSE_API)
        _mesa_debug(ctx, "glCullFace %s\n", _mesa_lookup_enum_by_nr(mode));
  
     if (mode!=GL_FRONT && mode!=GL_BACK && mode!=GL_FRONT_AND_BACK) {
        _mesa_error( ctx, GL_INVALID_ENUM, "glCullFace" );
        return;
     }
  
     if (ctx->Polygon.CullFaceMode == mode)
        return;
  
     FLUSH_VERTICES(ctx, _NEW_POLYGON);
     ctx->Polygon.CullFaceMode = mode;
  
     if (ctx->Driver.CullFace)
        ctx->Driver.CullFace( ctx, mode );
  }
  
  
  /**
   * Define front- and back-facing 
   *
   * \param mode orientation of front-facing polygons.
   *
   * \sa glFrontFace().
   *
   * Verifies the parameter and updates gl_polygon_attrib::FrontFace. On change
   * flushes the vertices and notifies the driver via
   * the dd_function_table::FrontFace callback.
   */
  void GLAPIENTRY
  _mesa_FrontFace( GLenum mode )
  {
     GET_CURRENT_CONTEXT(ctx);
     ASSERT_OUTSIDE_BEGIN_END(ctx);
  
     if (MESA_VERBOSE&VERBOSE_API)
        _mesa_debug(ctx, "glFrontFace %s\n", _mesa_lookup_enum_by_nr(mode));
  
     if (mode!=GL_CW && mode!=GL_CCW) {
        _mesa_error( ctx, GL_INVALID_ENUM, "glFrontFace" );
        return;
     }
  
     if (ctx->Polygon.FrontFace == mode)
        return;
  
     FLUSH_VERTICES(ctx, _NEW_POLYGON);
     ctx->Polygon.FrontFace = mode;
  
     ctx->Polygon._FrontBit = (GLboolean) (mode == GL_CW);
  
     if (ctx->Driver.FrontFace)
        ctx->Driver.FrontFace( ctx, mode );
  }
  
  
  /**
   * Set the polygon rasterization mode.
   *
   * \param face the polygons which \p mode applies to.
   * \param mode how polygons should be rasterized.
   *
   * \sa glPolygonMode(). 
   * 
   * Verifies the parameters and updates gl_polygon_attrib::FrontMode and
   * gl_polygon_attrib::BackMode. On change flushes the vertices and notifies the
   * driver via the dd_function_table::PolygonMode callback.
   */
  void GLAPIENTRY
  _mesa_PolygonMode( GLenum face, GLenum mode )
  {
     GET_CURRENT_CONTEXT(ctx);
     ASSERT_OUTSIDE_BEGIN_END(ctx);
  
     if (MESA_VERBOSE&VERBOSE_API)
        _mesa_debug(ctx, "glPolygonMode %s %s\n",
                    _mesa_lookup_enum_by_nr(face),
                    _mesa_lookup_enum_by_nr(mode));
  
     if (mode!=GL_POINT && mode!=GL_LINE && mode!=GL_FILL) {
        _mesa_error( ctx, GL_INVALID_ENUM, "glPolygonMode(mode)" );
        return;
     }
  
     switch (face) {
     case GL_FRONT:
        if (ctx->Polygon.FrontMode == mode)
  	 return;
        FLUSH_VERTICES(ctx, _NEW_POLYGON);
        ctx->Polygon.FrontMode = mode;
        break;
     case GL_FRONT_AND_BACK:
        if (ctx->Polygon.FrontMode == mode &&
  	  ctx->Polygon.BackMode == mode)
  	 return;
        FLUSH_VERTICES(ctx, _NEW_POLYGON);
        ctx->Polygon.FrontMode = mode;
        ctx->Polygon.BackMode = mode;
        break;
     case GL_BACK:
        if (ctx->Polygon.BackMode == mode)
  	 return;
        FLUSH_VERTICES(ctx, _NEW_POLYGON);
        ctx->Polygon.BackMode = mode;
        break;
     default:
        _mesa_error( ctx, GL_INVALID_ENUM, "glPolygonMode(face)" );
        return;
     }
  
     ctx->_TriangleCaps &= ~DD_TRI_UNFILLED;
     if (ctx->Polygon.FrontMode!=GL_FILL || ctx->Polygon.BackMode!=GL_FILL)
        ctx->_TriangleCaps |= DD_TRI_UNFILLED;
  
     if (ctx->Driver.PolygonMode) {
        (*ctx->Driver.PolygonMode)( ctx, face, mode );
     }
  }
  
  #if _HAVE_FULL_GL
  
  
  /**
   * This routine updates the ctx->Polygon.Stipple state.
   * If we're getting the stipple data from a PBO, we map the buffer
   * in order to access the data.
   * In any case, we obey the current pixel unpacking parameters when fetching
   * the stipple data.
   *
   * In the future, this routine should be used as a fallback, called via
   * ctx->Driver.PolygonStipple().  We'll have to update all the DRI drivers
   * too.
   */
  void
  _mesa_polygon_stipple(GLcontext *ctx, const GLubyte *pattern)
  {
     if (ctx->Unpack.BufferObj->Name) {
        /* Get/unpack the stipple pattern from a PBO */
        GLubyte *buf;
        if (!_mesa_validate_pbo_access(2, &ctx->Unpack, 32, 32, 1,
                                       GL_COLOR_INDEX, GL_BITMAP, pattern)) {
           _mesa_error(ctx, GL_INVALID_OPERATION,
                       "glPolygonStipple(bad PBO access)");
           return;
        }
        buf = (GLubyte *) ctx->Driver.MapBuffer(ctx, GL_PIXEL_UNPACK_BUFFER_EXT,
                                                GL_READ_ONLY_ARB,
                                                ctx->Unpack.BufferObj);
        if (!buf) {
           _mesa_error(ctx, GL_INVALID_OPERATION,
                       "glPolygonStipple(PBO mapped)");
           return;
        }
        buf = ADD_POINTERS(buf, pattern);
        _mesa_unpack_polygon_stipple(buf, ctx->PolygonStipple, &ctx->Unpack);
        ctx->Driver.UnmapBuffer(ctx, GL_PIXEL_UNPACK_BUFFER_EXT,
                                ctx->Unpack.BufferObj);
     }
     else {
        /* Get/unpack the stipple pattern from user memory */
        _mesa_unpack_polygon_stipple(pattern, ctx->PolygonStipple, &ctx->Unpack);
     }
  }
  
  
  /**
   * Called by glPolygonStipple.
   */
  void GLAPIENTRY
  _mesa_PolygonStipple( const GLubyte *pattern )
  {
     GET_CURRENT_CONTEXT(ctx);
     ASSERT_OUTSIDE_BEGIN_END(ctx);
  
     if (MESA_VERBOSE&VERBOSE_API)
        _mesa_debug(ctx, "glPolygonStipple\n");
  
     FLUSH_VERTICES(ctx, _NEW_POLYGONSTIPPLE);
  
     _mesa_polygon_stipple(ctx, pattern);
  
     if (ctx->Driver.PolygonStipple)
        ctx->Driver.PolygonStipple(ctx, pattern);
  }
  
  
  /**
   * Called by glPolygonStipple.
   */
  void GLAPIENTRY
  _mesa_GetPolygonStipple( GLubyte *dest )
  {
     GET_CURRENT_CONTEXT(ctx);
     ASSERT_OUTSIDE_BEGIN_END(ctx);
  
     if (MESA_VERBOSE&VERBOSE_API)
        _mesa_debug(ctx, "glGetPolygonStipple\n");
  
     /* XXX someday we may put this code into a separate function and call
      * it with ctx->Driver.GetPolygonStipple().
      */
     if (ctx->Pack.BufferObj->Name) {
        /* Put/pack the stipple pattern into a PBO */
        GLubyte *buf;
        if (!_mesa_validate_pbo_access(2, &ctx->Pack, 32, 32, 1,
                                       GL_COLOR_INDEX, GL_BITMAP, dest)) {
           _mesa_error(ctx, GL_INVALID_OPERATION,
                       "glGetPolygonStipple(bad PBO access)");
           return;
        }
        buf = (GLubyte *) ctx->Driver.MapBuffer(ctx, GL_PIXEL_PACK_BUFFER_EXT,
                                                GL_WRITE_ONLY_ARB,
                                                ctx->Pack.BufferObj);
        if (!buf) {
           _mesa_error(ctx, GL_INVALID_OPERATION,
                       "glGetPolygonStipple(PBO mapped)");
           return;
        }
        buf = ADD_POINTERS(buf, dest);
        _mesa_pack_polygon_stipple(ctx->PolygonStipple, buf, &ctx->Pack);
        ctx->Driver.UnmapBuffer(ctx, GL_PIXEL_PACK_BUFFER_EXT,
                                ctx->Pack.BufferObj);
     }
     else {
        /* Put/pack the stipple pattern into user memory */
        _mesa_pack_polygon_stipple(ctx->PolygonStipple, dest, &ctx->Pack);
     }
  }
  
  
  void GLAPIENTRY
  _mesa_PolygonOffset( GLfloat factor, GLfloat units )
  {
     GET_CURRENT_CONTEXT(ctx);
     ASSERT_OUTSIDE_BEGIN_END(ctx);
  
     if (MESA_VERBOSE&VERBOSE_API)
        _mesa_debug(ctx, "glPolygonOffset %f %f\n", factor, units);
  
     if (ctx->Polygon.OffsetFactor == factor &&
         ctx->Polygon.OffsetUnits == units)
        return;
  
     FLUSH_VERTICES(ctx, _NEW_POLYGON);
     ctx->Polygon.OffsetFactor = factor;
     ctx->Polygon.OffsetUnits = units;
  
     if (ctx->Driver.PolygonOffset)
        ctx->Driver.PolygonOffset( ctx, factor, units );
  }
  
  
  void GLAPIENTRY
  _mesa_PolygonOffsetEXT( GLfloat factor, GLfloat bias )
  {
     GET_CURRENT_CONTEXT(ctx);
     /* XXX mult by DepthMaxF here??? */
     _mesa_PolygonOffset(factor, bias * ctx->DrawBuffer->_DepthMaxF );
  }
  
  #endif
  
  
  /**********************************************************************/
  /** \name State Management */
  /*@{*/
  
  /*
   * Check polygon state and set DD_TRI_CULL_FRONT_BACK and/or DD_TRI_OFFSET
   * in ctx->_TriangleCaps if needed.
   */
  void _mesa_update_polygon( GLcontext *ctx )
  {
     ctx->_TriangleCaps &= ~(DD_TRI_CULL_FRONT_BACK | DD_TRI_OFFSET);
  
     if (ctx->Polygon.CullFlag && ctx->Polygon.CullFaceMode == GL_FRONT_AND_BACK)
        ctx->_TriangleCaps |= DD_TRI_CULL_FRONT_BACK;
  
     /* Any Polygon offsets enabled? */
     if (ctx->Polygon.OffsetPoint ||
         ctx->Polygon.OffsetLine ||
         ctx->Polygon.OffsetFill) {
        ctx->_TriangleCaps |= DD_TRI_OFFSET;
     }
  }
  
  /*@}*/
  
  
  /**********************************************************************/
  /** \name Initialization */
  /*@{*/
  
  /**
   * Initialize the context polygon state.
   *
   * \param ctx GL context.
   *
   * Initializes __GLcontextRec::Polygon and __GLcontextRec::PolygonStipple
   * attribute groups.
   */
  void _mesa_init_polygon( GLcontext * ctx )
  {
     /* Polygon group */
     ctx->Polygon.CullFlag = GL_FALSE;
     ctx->Polygon.CullFaceMode = GL_BACK;
     ctx->Polygon.FrontFace = GL_CCW;
     ctx->Polygon._FrontBit = 0;
     ctx->Polygon.FrontMode = GL_FILL;
     ctx->Polygon.BackMode = GL_FILL;
     ctx->Polygon.SmoothFlag = GL_FALSE;
     ctx->Polygon.StippleFlag = GL_FALSE;
     ctx->Polygon.OffsetFactor = 0.0F;
     ctx->Polygon.OffsetUnits = 0.0F;
     ctx->Polygon.OffsetPoint = GL_FALSE;
     ctx->Polygon.OffsetLine = GL_FALSE;
     ctx->Polygon.OffsetFill = GL_FALSE;
  
  
     /* Polygon Stipple group */
     MEMSET( ctx->PolygonStipple, 0xff, 32*sizeof(GLuint) );
  }
  
  /*@}*/
  