src/mesa/main/clip.c

   1 /*
   2  * Mesa 3-D graphics library
   3  *
   4  * Copyright (C) 1999-2005  Brian Paul   All Rights Reserved.
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a
   7  * copy of this software and associated documentation files (the "Software"),
   8  * to deal in the Software without restriction, including without limitation
   9  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  10  * and/or sell copies of the Software, and to permit persons to whom the
  11  * Software is furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included
  14  * in all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  17  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  20  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  21  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  22  * OTHER DEALINGS IN THE SOFTWARE.
  23  */
  24
  25
  26 #include "glheader.h"
  27 #include "clip.h"
  28 #include "context.h"
  29 #include "macros.h"
  30 #include "mtypes.h"
  31
  32 #include "math/m_matrix.h"
  33
  34
  35 /**
  36  * Update derived clip plane state.
  37  */
  38 void
  39 _mesa_update_clip_plane(struct gl_context *ctx, GLuint plane)
  40 {
  41    if (_math_matrix_is_dirty(ctx->ProjectionMatrixStack.Top))
  42       _math_matrix_analyse( ctx->ProjectionMatrixStack.Top );
  43
  44    /* Clip-Space Plane = Eye-Space Plane * Projection Matrix */
  45    _mesa_transform_vector(ctx->Transform._ClipUserPlane[plane],
  46                           ctx->Transform.EyeUserPlane[plane],
  47                           ctx->ProjectionMatrixStack.Top->inv);
  48 }
  49
  50
  51 void GLAPIENTRY
  52 _mesa_ClipPlane( GLenum plane, const GLdouble *eq )
  53 {
  54    GET_CURRENT_CONTEXT(ctx);
  55    GLint p;
  56    GLfloat equation[4];
  57
  58    p = (GLint) plane - (GLint) GL_CLIP_PLANE0;
  59    if (p < 0 || p >= (GLint) ctx->Const.MaxClipPlanes) {
  60       _mesa_error( ctx, GL_INVALID_ENUM, "glClipPlane" );
  61       return;
  62    }
  63
  64    equation[0] = (GLfloat) eq[0];
  65    equation[1] = (GLfloat) eq[1];
  66    equation[2] = (GLfloat) eq[2];
  67    equation[3] = (GLfloat) eq[3];
  68
  69    /*
  70     * The equation is transformed by the transpose of the inverse of the
  71     * current modelview matrix and stored in the resulting eye coordinates.
  72     *
  73     * KW: Eqn is then transformed to the current clip space, where user
  74     * clipping now takes place.  The clip-space equations are recalculated
  75     * whenever the projection matrix changes.
  76     */
  77    if (_math_matrix_is_dirty(ctx->ModelviewMatrixStack.Top))
  78       _math_matrix_analyse( ctx->ModelviewMatrixStack.Top );
  79
  80    _mesa_transform_vector( equation, equation,
  81                            ctx->ModelviewMatrixStack.Top->inv );
  82
  83    if (TEST_EQ_4V(ctx->Transform.EyeUserPlane[p], equation))
  84       return;
  85
  86    /* EyeUserPlane is used by program state constants. */
  87    FLUSH_VERTICES(ctx, _NEW_TRANSFORM);
  88    ctx->NewDriverState |= ctx->DriverFlags.NewClipPlane;
  89    COPY_4FV(ctx->Transform.EyeUserPlane[p], equation);
  90
  91    if (ctx->Transform.ClipPlanesEnabled & (1 << p)) {
  92       _mesa_update_clip_plane(ctx, p);
  93    }
  94
  95    if (ctx->Driver.ClipPlane)
  96       ctx->Driver.ClipPlane( ctx, plane, equation );
  97 }
  98
  99
 100 void GLAPIENTRY
 101 _mesa_GetClipPlane( GLenum plane, GLdouble *equation )
 102 {
 103    GET_CURRENT_CONTEXT(ctx);
 104    GLint p;
 105
 106    p = (GLint) (plane - GL_CLIP_PLANE0);
 107    if (p < 0 || p >= (GLint) ctx->Const.MaxClipPlanes) {
 108       _mesa_error( ctx, GL_INVALID_ENUM, "glGetClipPlane" );
 109       return;
 110    }
 111
 112    equation[0] = (GLdouble) ctx->Transform.EyeUserPlane[p][0];
 113    equation[1] = (GLdouble) ctx->Transform.EyeUserPlane[p][1];
 114    equation[2] = (GLdouble) ctx->Transform.EyeUserPlane[p][2];
 115    equation[3] = (GLdouble) ctx->Transform.EyeUserPlane[p][3];
 116 }