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  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.    FLUSH_VERTICES(ctx, _NEW_TRANSFORM);
  87.    COPY_4FV(ctx->Transform.EyeUserPlane[p], equation);
  88.  
  89.    if (ctx->Transform.ClipPlanesEnabled & (1 << p)) {
  90.       _mesa_update_clip_plane(ctx, p);
  91.    }
  92.  
  93.    if (ctx->Driver.ClipPlane)
  94.       ctx->Driver.ClipPlane( ctx, plane, equation );
  95. }
  96.  
  97.  
  98. void GLAPIENTRY
  99. _mesa_GetClipPlane( GLenum plane, GLdouble *equation )
  100. {
  101.    GET_CURRENT_CONTEXT(ctx);
  102.    GLint p;
  103.  
  104.    p = (GLint) (plane - GL_CLIP_PLANE0);
  105.    if (p < 0 || p >= (GLint) ctx->Const.MaxClipPlanes) {
  106.       _mesa_error( ctx, GL_INVALID_ENUM, "glGetClipPlane" );
  107.       return;
  108.    }
  109.  
  110.    equation[0] = (GLdouble) ctx->Transform.EyeUserPlane[p][0];
  111.    equation[1] = (GLdouble) ctx->Transform.EyeUserPlane[p][1];
  112.    equation[2] = (GLdouble) ctx->Transform.EyeUserPlane[p][2];
  113.    equation[3] = (GLdouble) ctx->Transform.EyeUserPlane[p][3];
  114. }
  115.