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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