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 */
38void
39_mesa_update_clip_plane(struct gl_context *ctx, GLuint plane)
40{
41   /* make sure the inverse is up to date */
42   if (_math_matrix_is_dirty(ctx->ProjectionMatrixStack.Top))
43      _math_matrix_analyse( ctx->ProjectionMatrixStack.Top );
44
45   /* Clip-Space Plane = Eye-Space Plane * Projection Matrix */
46   _mesa_transform_vector(ctx->Transform._ClipUserPlane[plane],
47                          ctx->Transform.EyeUserPlane[plane],
48                          ctx->ProjectionMatrixStack.Top->inv);
49}
50
51
52void GLAPIENTRY
53_mesa_ClipPlane( GLenum plane, const GLdouble *eq )
54{
55   GET_CURRENT_CONTEXT(ctx);
56   GLint p;
57   GLfloat equation[4];
58
59   p = (GLint) plane - (GLint) GL_CLIP_PLANE0;
60   if (p < 0 || p >= (GLint) ctx->Const.MaxClipPlanes) {
61      _mesa_error( ctx, GL_INVALID_ENUM, "glClipPlane" );
62      return;
63   }
64
65   equation[0] = (GLfloat) eq[0];
66   equation[1] = (GLfloat) eq[1];
67   equation[2] = (GLfloat) eq[2];
68   equation[3] = (GLfloat) eq[3];
69
70   /*
71    * The equation is transformed by the transpose of the inverse of the
72    * current modelview matrix and stored in the resulting eye coordinates.
73    *
74    * KW: Eqn is then transformed to the current clip space, where user
75    * clipping now takes place.  The clip-space equations are recalculated
76    * whenever the projection matrix changes.
77    */
78   if (_math_matrix_is_dirty(ctx->ModelviewMatrixStack.Top))
79      _math_matrix_analyse( ctx->ModelviewMatrixStack.Top );
80
81   _mesa_transform_vector( equation, equation,
82                           ctx->ModelviewMatrixStack.Top->inv );
83
84   if (TEST_EQ_4V(ctx->Transform.EyeUserPlane[p], equation))
85      return;
86
87   /* EyeUserPlane is used by program state constants. */
88   FLUSH_VERTICES(ctx, _NEW_TRANSFORM, GL_TRANSFORM_BIT);
89   ctx->NewDriverState |= ctx->DriverFlags.NewClipPlane;
90   COPY_4FV(ctx->Transform.EyeUserPlane[p], equation);
91
92   if (ctx->Transform.ClipPlanesEnabled & (1 << p)) {
93      _mesa_update_clip_plane(ctx, p);
94   }
95
96   if (ctx->Driver.ClipPlane)
97      ctx->Driver.ClipPlane( ctx, plane, equation );
98}
99
100
101void GLAPIENTRY
102_mesa_GetClipPlane( GLenum plane, GLdouble *equation )
103{
104   GET_CURRENT_CONTEXT(ctx);
105   GLint p;
106
107   p = (GLint) (plane - GL_CLIP_PLANE0);
108   if (p < 0 || p >= (GLint) ctx->Const.MaxClipPlanes) {
109      _mesa_error( ctx, GL_INVALID_ENUM, "glGetClipPlane" );
110      return;
111   }
112
113   equation[0] = (GLdouble) ctx->Transform.EyeUserPlane[p][0];
114   equation[1] = (GLdouble) ctx->Transform.EyeUserPlane[p][1];
115   equation[2] = (GLdouble) ctx->Transform.EyeUserPlane[p][2];
116   equation[3] = (GLdouble) ctx->Transform.EyeUserPlane[p][3];
117}
118