src/mesa/main/clip.c

   1 /* $Id: clip.c,v 1.26 2002/10/24 23:57:19 brianp Exp $ */
   2
   3 /*
   4  * Mesa 3-D graphics library
   5  * Version:  3.5
   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 "mmath.h"
  33 #include "mtypes.h"
  34
  35 #include "math/m_xform.h"
  36 #include "math/m_matrix.h"
  37
  38
  39
  40 /**********************************************************************/
  41 /*                     Get/Set User clip-planes.                      */
  42 /**********************************************************************/
  43
  44
  45
  46 void
  47 _mesa_ClipPlane( GLenum plane, const GLdouble *eq )
  48 {
  49    GET_CURRENT_CONTEXT(ctx);
  50    GLint p;
  51    GLfloat equation[4];
  52    ASSERT_OUTSIDE_BEGIN_END(ctx);
  53
  54    p = (GLint) plane - (GLint) GL_CLIP_PLANE0;
  55    if (p < 0 || p >= (GLint) ctx->Const.MaxClipPlanes) {
  56       _mesa_error( ctx, GL_INVALID_ENUM, "glClipPlane" );
  57       return;
  58    }
  59
  60    equation[0] = (GLfloat) eq[0];
  61    equation[1] = (GLfloat) eq[1];
  62    equation[2] = (GLfloat) eq[2];
  63    equation[3] = (GLfloat) eq[3];
  64
  65    /*
  66     * The equation is transformed by the transpose of the inverse of the
  67     * current modelview matrix and stored in the resulting eye coordinates.
  68     *
  69     * KW: Eqn is then transformed to the current clip space, where user
  70     * clipping now takes place.  The clip-space equations are recalculated
  71     * whenever the projection matrix changes.
  72     */
  73    if (ctx->ModelviewMatrixStack.Top->flags & MAT_DIRTY)
  74       _math_matrix_analyse( ctx->ModelviewMatrixStack.Top );
  75
  76    _mesa_transform_vector( equation, equation,
  77                            ctx->ModelviewMatrixStack.Top->inv );
  78
  79    if (TEST_EQ_4V(ctx->Transform.EyeUserPlane[p], equation))
  80       return;
  81
  82    FLUSH_VERTICES(ctx, _NEW_TRANSFORM);
  83    COPY_4FV(ctx->Transform.EyeUserPlane[p], equation);
  84
  85    /* Update derived state.  This state also depends on the projection
  86     * matrix, and is recalculated on changes to the projection matrix by
  87     * code in _mesa_update_state().
  88     */
  89    if (ctx->Transform.ClipPlanesEnabled & (1 << p)) {
  90       if (ctx->ProjectionMatrixStack.Top->flags & MAT_DIRTY)
  91          _math_matrix_analyse( ctx->ProjectionMatrixStack.Top );
  92
  93       _mesa_transform_vector( ctx->Transform._ClipUserPlane[p],
  94                            ctx->Transform.EyeUserPlane[p],
  95                            ctx->ProjectionMatrixStack.Top->inv );
  96    }
  97
  98    if (ctx->Driver.ClipPlane)
  99       ctx->Driver.ClipPlane( ctx, plane, equation );
 100 }
 101
 102
 103 void
 104 _mesa_GetClipPlane( GLenum plane, GLdouble *equation )
 105 {
 106    GET_CURRENT_CONTEXT(ctx);
 107    GLint p;
 108    ASSERT_OUTSIDE_BEGIN_END(ctx);
 109
 110    p = (GLint) (plane - GL_CLIP_PLANE0);
 111    if (p < 0 || p >= (GLint) ctx->Const.MaxClipPlanes) {
 112       _mesa_error( ctx, GL_INVALID_ENUM, "glGetClipPlane" );
 113       return;
 114    }
 115
 116    equation[0] = (GLdouble) ctx->Transform.EyeUserPlane[p][0];
 117    equation[1] = (GLdouble) ctx->Transform.EyeUserPlane[p][1];
 118    equation[2] = (GLdouble) ctx->Transform.EyeUserPlane[p][2];
 119    equation[3] = (GLdouble) ctx->Transform.EyeUserPlane[p][3];
 120 }