src/mesa/main/clip.c

   1 /* $Id: clip.c,v 1.21 2001/03/07 05:06:11 brianp Exp $ */
   2
   3 /*
   4  * Mesa 3-D graphics library
   5  * Version:  3.3
   6  *
   7  * Copyright (C) 1999  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 #ifdef PC_HEADER
  29 #include "all.h"
  30 #else
  31 #include "glheader.h"
  32 #include "clip.h"
  33 #include "context.h"
  34 #include "macros.h"
  35 #include "mmath.h"
  36 #include "mtypes.h"
  37
  38 #include "math/m_xform.h"
  39 #include "math/m_matrix.h"
  40 #endif
  41
  42
  43
  44
  45
  46
  47 /**********************************************************************/
  48 /*                     Get/Set User clip-planes.                      */
  49 /**********************************************************************/
  50
  51
  52
  53 void
  54 _mesa_ClipPlane( GLenum plane, const GLdouble *eq )
  55 {
  56    GET_CURRENT_CONTEXT(ctx);
  57    GLint p;
  58    GLfloat equation[4];
  59    ASSERT_OUTSIDE_BEGIN_END(ctx);
  60
  61    p = (GLint) plane - (GLint) GL_CLIP_PLANE0;
  62    if (p < 0 || p >= (GLint) ctx->Const.MaxClipPlanes) {
  63       _mesa_error( ctx, GL_INVALID_ENUM, "glClipPlane" );
  64       return;
  65    }
  66
  67    equation[0] = eq[0];
  68    equation[1] = eq[1];
  69    equation[2] = eq[2];
  70    equation[3] = eq[3];
  71
  72    /*
  73     * The equation is transformed by the transpose of the inverse of the
  74     * current modelview matrix and stored in the resulting eye coordinates.
  75     *
  76     * KW: Eqn is then transformed to the current clip space, where user
  77     * clipping now takes place.  The clip-space equations are recalculated
  78     * whenever the projection matrix changes.
  79     */
  80    if (ctx->ModelView.flags & MAT_DIRTY)
  81       _math_matrix_analyse( &ctx->ModelView );
  82
  83    _mesa_transform_vector( equation, equation, ctx->ModelView.inv );
  84
  85    if (TEST_EQ_4V(ctx->Transform.EyeUserPlane[p], equation))
  86       return;
  87
  88    FLUSH_VERTICES(ctx, _NEW_TRANSFORM);
  89    COPY_4FV(ctx->Transform.EyeUserPlane[p], equation);
  90
  91    /* Update derived state.  This state also depends on the projection
  92     * matrix, and is recalculated on changes to the projection matrix by
  93     * code in _mesa_update_state().
  94     */
  95    if (ctx->Transform.ClipEnabled[p]) {
  96       if (ctx->ProjectionMatrix.flags & MAT_DIRTY)
  97          _math_matrix_analyse( &ctx->ProjectionMatrix );
  98
  99       _mesa_transform_vector( ctx->Transform._ClipUserPlane[p],
 100                            ctx->Transform.EyeUserPlane[p],
 101                            ctx->ProjectionMatrix.inv );
 102    }
 103
 104    if (ctx->Driver.ClipPlane)
 105       ctx->Driver.ClipPlane( ctx, plane, equation );
 106 }
 107
 108
 109 void
 110 _mesa_GetClipPlane( GLenum plane, GLdouble *equation )
 111 {
 112    GET_CURRENT_CONTEXT(ctx);
 113    GLint p;
 114    ASSERT_OUTSIDE_BEGIN_END(ctx);
 115
 116    p = (GLint) (plane - GL_CLIP_PLANE0);
 117    if (p < 0 || p >= (GLint) ctx->Const.MaxClipPlanes) {
 118       _mesa_error( ctx, GL_INVALID_ENUM, "glGetClipPlane" );
 119       return;
 120    }
 121
 122    equation[0] = (GLdouble) ctx->Transform.EyeUserPlane[p][0];
 123    equation[1] = (GLdouble) ctx->Transform.EyeUserPlane[p][1];
 124    equation[2] = (GLdouble) ctx->Transform.EyeUserPlane[p][2];
 125    equation[3] = (GLdouble) ctx->Transform.EyeUserPlane[p][3];
 126 }