root/OpenSceneGraph/trunk/include/osg/StencilTwoSided @ 13041

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1/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield
2 *
3 * This library is open source and may be redistributed and/or modified under
4 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
5 * (at your option) any later version.  The full license is in LICENSE file
6 * included with this distribution, and on the openscenegraph.org website.
7 *
8 * This library is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11 * OpenSceneGraph Public License for more details.
12*/
13
14#ifndef OSG_STENCILTWOSIDED
15#define OSG_STENCILTWOSIDED 1
16
17#include <osg/Stencil>
18
19namespace osg {
20
21#ifndef GL_STENCIL_TEST_TWO_SIDE
22#define GL_STENCIL_TEST_TWO_SIDE 0x8910
23#endif
24
25/** Provides OpenGL two sided stencil functionality, also known as separate stencil.
26 *  It enables to specify different stencil function for front and back facing polygons.
27 *  Two sided stenciling is used usually to eliminate the need of two rendering passes
28 *  when using standard stenciling functions. See also \sa osg::Stencil.
29 *
30 *  Two sided stenciling is available since OpenGL 2.0. It is also supported by
31 *  EXT_stencil_two_side extension especially on Nvidia cards.
32 *  Another extension introduced by ATI is ATI_separate_stencil. However, ATI's extension
33 *  is limited to have reference and mask value the same for both faces.
34 *  ATI's extension is currently not supported by the current implementation.
35 *
36 *  osg::StencilTwoSided does nothing if OpenGL 2.0 or EXT_stencil_two_side are not available.
37*/
38class OSG_EXPORT StencilTwoSided : public StateAttribute
39{
40    public :
41
42
43        StencilTwoSided();
44
45        /** Copy constructor using CopyOp to manage deep vs shallow copy.*/
46        StencilTwoSided(const StencilTwoSided& stencil,const CopyOp& copyop=CopyOp::SHALLOW_COPY);
47
48        META_StateAttribute(osg, StencilTwoSided, STENCIL);
49
50        /** return -1 if *this < *rhs, 0 if *this==*rhs, 1 if *this>*rhs.*/
51        virtual int compare(const StateAttribute& sa) const;
52
53        virtual bool getModeUsage(StateAttribute::ModeUsage& usage) const
54        {
55            usage.usesMode(GL_STENCIL_TEST);
56            return true;
57        }
58
59        enum Face
60        {
61            FRONT = 0,
62            BACK = 1
63        };
64
65        enum Function
66        {
67            NEVER = GL_NEVER,
68            LESS = GL_LESS,
69            EQUAL = GL_EQUAL,
70            LEQUAL = GL_LEQUAL,
71            GREATER = GL_GREATER,
72            NOTEQUAL = GL_NOTEQUAL,
73            GEQUAL = GL_GEQUAL,
74            ALWAYS = GL_ALWAYS
75        };
76
77        inline void setFunction(Face face, Function func,int ref,unsigned int mask)
78        {
79            _func[face] = func;
80            _funcRef[face] = ref;
81            _funcMask[face] = mask;
82        }
83
84        inline void setFunction(Face face, Function func) { _func[face] = func; }
85        inline Function getFunction(Face face) const { return _func[face]; }
86
87        inline void setFunctionRef(Face face, int ref) { _funcRef[face]=ref; }
88        inline int getFunctionRef(Face face) const { return _funcRef[face]; }
89
90        inline void setFunctionMask(Face face, unsigned int mask) { _funcMask[face]=mask; }
91        inline unsigned int getFunctionMask(Face face) const { return _funcMask[face]; }
92
93
94        enum Operation
95        {
96            KEEP = GL_KEEP,
97            ZERO = GL_ZERO,
98            REPLACE = GL_REPLACE,
99            INCR = GL_INCR,
100            DECR = GL_DECR,
101            INVERT = GL_INVERT,
102            INCR_WRAP = GL_INCR_WRAP,
103            DECR_WRAP = GL_DECR_WRAP
104        };
105
106        /** set the operations to apply when the various stencil and depth
107          * tests fail or pass.  First parameter is to control the operation
108          * when the stencil test fails.  The second parameter is to control the
109          * operation when the stencil test passes, but depth test fails. The
110          * third parameter controls the operation when both the stencil test
111          * and depth pass.  Ordering of parameter is the same as if using
112          * glStencilOp(,,).*/
113        inline void setOperation(Face face, Operation sfail, Operation zfail, Operation zpass)
114        {
115            _sfail[face] = sfail;
116            _zfail[face] = zfail;
117            _zpass[face] = zpass;
118        }
119
120        /** set the operation when the stencil test fails.*/
121        inline void setStencilFailOperation(Face face, Operation sfail) { _sfail[face] = sfail; }
122
123        /** get the operation when the stencil test fails.*/
124        inline Operation getStencilFailOperation(Face face) const { return _sfail[face]; }
125
126        /** set the operation when the stencil test passes but the depth test fails.*/
127        inline void setStencilPassAndDepthFailOperation(Face face, Operation zfail) { _zfail[face]=zfail; }
128
129        /** get the operation when the stencil test passes but the depth test fails.*/
130        inline Operation getStencilPassAndDepthFailOperation(Face face) const { return _zfail[face]; }
131
132        /** set the operation when both the stencil test and the depth test pass.*/
133        inline void setStencilPassAndDepthPassOperation(Face face, Operation zpass) { _zpass[face]=zpass; }
134
135        /** get the operation when both the stencil test and the depth test pass.*/
136        inline Operation getStencilPassAndDepthPassOperation(Face face) const { return _zpass[face]; }
137
138
139        inline void setWriteMask(Face face, unsigned int mask) { _writeMask[face] = mask; }
140
141        inline unsigned int getWriteMask(Face face) const { return _writeMask[face]; }
142
143
144        virtual void apply(State& state) const;
145
146    public:
147
148        /** Extensions class which encapsulates the querying of extensions and
149          * associated function pointers, and provide convenience wrappers to
150          * check for the extensions or use the associated functions.
151        */
152        class OSG_EXPORT Extensions : public osg::Referenced
153        {
154            public:
155                Extensions(unsigned int contextID);
156
157                Extensions(const Extensions& rhs);
158
159                void lowestCommonDenominator(const Extensions& rhs);
160
161                void setupGLExtensions(unsigned int contextID);
162
163                void setStencilTwoSidedSupported(bool flag) { _isStencilTwoSidedSupported=flag; }
164                bool isStencilTwoSidedSupported() const { return _isStencilTwoSidedSupported; }
165                void setOpenGL20Supported(bool flag) { _isOpenGL20Supported=flag; }
166                bool isOpenGL20Supported() const { return _isOpenGL20Supported; }
167                void setSeparateStencilSupported(bool flag) { _isSeparateStencilSupported=flag; }
168                bool isSeparateStencilSupported() const { return _isSeparateStencilSupported; }
169
170                void glActiveStencilFace(GLenum face) const;
171                void glStencilOpSeparate(GLenum face, GLenum sfail, GLenum dpfail, GLenum dppass) const;
172                void glStencilMaskSeparate(GLenum face, GLuint mask) const;
173                void glStencilFuncSeparate(GLenum face, GLenum func, GLint ref, GLuint mask) const;
174                void glStencilFuncSeparateATI(GLenum frontfunc, GLenum backfunc, GLint ref, GLuint mask) const;
175
176            protected:
177
178                ~Extensions() {}
179
180                bool _isStencilTwoSidedSupported;
181                bool _isOpenGL20Supported;
182                bool _isSeparateStencilSupported;
183
184                typedef void (GL_APIENTRY * ActiveStencilFaceProc) (GLenum);
185                typedef void (GL_APIENTRY * StencilOpSeparate) (GLenum face, GLenum sfail, GLenum dpfail, GLenum dppass);
186                typedef void (GL_APIENTRY * StencilMaskSeparate) (GLenum face, GLuint mask);
187                typedef void (GL_APIENTRY * StencilFuncSeparate) (GLenum face, GLenum func, GLint ref, GLuint mask);
188                typedef void (GL_APIENTRY * StencilFuncSeparateATI) (GLenum frontfunc, GLenum backfunc, GLint ref, GLuint mask);
189
190                ActiveStencilFaceProc _glActiveStencilFace;
191                StencilOpSeparate _glStencilOpSeparate;
192                StencilMaskSeparate _glStencilMaskSeparate;
193                StencilFuncSeparate _glStencilFuncSeparate;
194                StencilFuncSeparate _glStencilFuncSeparateATI;
195        };
196
197        /** Function to call to get the extension of a specified context.
198          * If the Extension object for that context has not yet been created
199          * and the 'createIfNotInitalized' flag been set to false then returns NULL.
200          * If 'createIfNotInitalized' is true then the Extensions object is
201          * automatically created. However, in this case the extension object
202          * will only be created with the graphics context associated with ContextID.
203        */
204        static Extensions* getExtensions(unsigned int contextID,bool createIfNotInitalized);
205
206        /** The setExtensions method allows users to override the extensions across graphics contexts.
207          * Typically used when you have different extensions supported across graphics pipes
208          * but need to ensure that they all use the same low common denominator extensions.
209        */
210        static void setExtensions(unsigned int contextID,Extensions* extensions);
211
212
213    protected:
214
215        virtual ~StencilTwoSided();
216
217        Function            _func[2];
218        int                 _funcRef[2];
219        unsigned int        _funcMask[2];
220
221        Operation           _sfail[2];
222        Operation           _zfail[2];
223        Operation           _zpass[2];
224
225        unsigned int        _writeMask[2];
226
227};
228
229}
230
231#endif
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