src/mesa/main/clip.c

   1 /* $Id: clip.c,v 1.27 2003/03/01 01:50:20 brianp Exp $ */
   2
   3 /*
   4  * Mesa 3-D graphics library
   5  * Version:  5.1
   6  *
   7  * Copyright (C) 1999-2001  Brian Paul   All Rights Reserved.
   8  *
   9  * Permission is hereby granted, free of charge, to any person obtaining a
  10  * copy of this software and associated documentation files (the "Software"),
  11  * to deal in the Software without restriction, including without limitation
  12  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  13  * and/or sell copies of the Software, and to permit persons to whom the
  14  * Software is furnished to do so, subject to the following conditions:
  15  *
  16  * The above copyright notice and this permission notice shall be included
  17  * in all copies or substantial portions of the Software.
  18  *
  19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  20  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  21  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  22  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  23  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  24  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  25  */
  26
  27
  28 #include "glheader.h"
  29 #include "clip.h"
  30 #include "context.h"
  31 #include "macros.h"
  32 #include "mtypes.h"
  33
  34 #include "math/m_xform.h"
  35 #include "math/m_matrix.h"
  36
  37
  38
  39 /**********************************************************************/
  40 /*                     Get/Set User clip-planes.                      */
  41 /**********************************************************************/
  42
  43
  44
  45 void
  46 _mesa_ClipPlane( GLenum plane, const GLdouble *eq )
  47 {
  48    GET_CURRENT_CONTEXT(ctx);
  49    GLint p;
  50    GLfloat equation[4];
  51    ASSERT_OUTSIDE_BEGIN_END(ctx);
  52
  53    p = (GLint) plane - (GLint) GL_CLIP_PLANE0;
  54    if (p < 0 || p >= (GLint) ctx->Const.MaxClipPlanes) {
  55       _mesa_error( ctx, GL_INVALID_ENUM, "glClipPlane" );
  56       return;
  57    }
  58
  59    equation[0] = (GLfloat) eq[0];
  60    equation[1] = (GLfloat) eq[1];
  61    equation[2] = (GLfloat) eq[2];
  62    equation[3] = (GLfloat) eq[3];
  63
  64    /*
  65     * The equation is transformed by the transpose of the inverse of the
  66     * current modelview matrix and stored in the resulting eye coordinates.
  67     *
  68     * KW: Eqn is then transformed to the current clip space, where user
  69     * clipping now takes place.  The clip-space equations are recalculated
  70     * whenever the projection matrix changes.
  71     */
  72    if (ctx->ModelviewMatrixStack.Top->flags & MAT_DIRTY)
  73       _math_matrix_analyse( ctx->ModelviewMatrixStack.Top );
  74
  75    _mesa_transform_vector( equation, equation,
  76                            ctx->ModelviewMatrixStack.Top->inv );
  77
  78    if (TEST_EQ_4V(ctx->Transform.EyeUserPlane[p], equation))
  79       return;
  80
  81    FLUSH_VERTICES(ctx, _NEW_TRANSFORM);
  82    COPY_4FV(ctx->Transform.EyeUserPlane[p], equation);
  83
  84    /* Update derived state.  This state also depends on the projection
  85     * matrix, and is recalculated on changes to the projection matrix by
  86     * code in _mesa_update_state().
  87     */
  88    if (ctx->Transform.ClipPlanesEnabled & (1 << p)) {
  89       if (ctx->ProjectionMatrixStack.Top->flags & MAT_DIRTY)
  90          _math_matrix_analyse( ctx->ProjectionMatrixStack.Top );
  91
  92       _mesa_transform_vector( ctx->Transform._ClipUserPlane[p],
  93                            ctx->Transform.EyeUserPlane[p],
  94                            ctx->ProjectionMatrixStack.Top->inv );
  95    }
  96
  97    if (ctx->Driver.ClipPlane)
  98       ctx->Driver.ClipPlane( ctx, plane, equation );
  99 }
 100
 101
 102 void
 103 _mesa_GetClipPlane( GLenum plane, GLdouble *equation )
 104 {
 105    GET_CURRENT_CONTEXT(ctx);
 106    GLint p;
 107    ASSERT_OUTSIDE_BEGIN_END(ctx);
 108
 109    p = (GLint) (plane - GL_CLIP_PLANE0);
 110    if (p < 0 || p >= (GLint) ctx->Const.MaxClipPlanes) {
 111       _mesa_error( ctx, GL_INVALID_ENUM, "glGetClipPlane" );
 112       return;
 113    }
 114
 115    equation[0] = (GLdouble) ctx->Transform.EyeUserPlane[p][0];
 116    equation[1] = (GLdouble) ctx->Transform.EyeUserPlane[p][1];
 117    equation[2] = (GLdouble) ctx->Transform.EyeUserPlane[p][2];
 118    equation[3] = (GLdouble) ctx->Transform.EyeUserPlane[p][3];
 119 }