222 lines
8.9 KiB
C++
222 lines
8.9 KiB
C++
/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield
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*
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* This library is open source and may be redistributed and/or modified under
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* the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
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* (at your option) any later version. The full license is in LICENSE file
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* included with this distribution, and on the openscenegraph.org website.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* OpenSceneGraph Public License for more details.
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*/
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#ifndef OSG_BLENDFUNC
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#define OSG_BLENDFUNC 1
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#include <osg/StateAttribute>
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#ifndef GL_VERSION_1_2
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#define GL_CONSTANT_COLOR 0x8001
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#define GL_ONE_MINUS_CONSTANT_COLOR 0x8002
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#define GL_CONSTANT_ALPHA 0x8003
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#define GL_ONE_MINUS_CONSTANT_ALPHA 0x8004
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#define GL_BLEND_COLOR 0x8005
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#endif
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#ifndef GL_VERSION_1_4
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#define GL_BLEND_DST_RGB 0x80C8
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#define GL_BLEND_SRC_RGB 0x80C9
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#define GL_BLEND_DST_ALPHA 0x80CA
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#define GL_BLEND_SRC_ALPHA 0x80CB
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#endif
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namespace osg {
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/** Encapsulates OpenGL blend/transparency state.
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*
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* Blending combines incoming fragment with a fragment
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* already present in the target buffer.
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*
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* OpenGL 1.1 supports following source and destination blending factors:
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* GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA,
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* GL_DST_ALPHA, GL_ONE_MINUS_DST_ALPHA,
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* GL_ZERO, GL_ONE.
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*
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* Moreover, there are three source-only blending factors:
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* GL_DST_COLOR, GL_ONE_MINUS_DST_COLOR, GL_SRC_ALPHA_SATURATE
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* and two destination-only blending factors:
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* GL_SRC_COLOR, GL_ONE_MINUS_SRC_COLOR.
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* OpenGL 1.4 allowed to use these five blending factors
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* as both - source and destination blending factors.
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*
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* Following four source and destination blending factors
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* were added by Imaging subset of OpenGL 1.2
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* and made mandatory by OpenGL 1.4:
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* GL_CONSTANT_COLOR, GL_ONE_MINUS_CONSTANT_COLOR,
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* GL_CONSTANT_ALPHA, GL_ONE_MINUS_CONSTANT_ALPHA
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*
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* OpenGL 1.4 further provides glBlendFuncSeparate
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* (promoted from GL_EXT_blend_func_separate).
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* It makes possible to set blending functions for RGB and Alpha separately.
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* Before, it was possible to set just one blending function for RGBA.
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*/
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class OSG_EXPORT BlendFunc : public StateAttribute
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{
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public :
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BlendFunc();
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BlendFunc(GLenum source, GLenum destination);
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BlendFunc(GLenum source, GLenum destination, GLenum source_alpha, GLenum destination_alpha);
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/** Copy constructor using CopyOp to manage deep vs shallow copy. */
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BlendFunc(const BlendFunc& trans,const CopyOp& copyop=CopyOp::SHALLOW_COPY):
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StateAttribute(trans,copyop),
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_source_factor(trans._source_factor),
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_destination_factor(trans._destination_factor),
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_source_factor_alpha(trans._source_factor_alpha),
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_destination_factor_alpha(trans._destination_factor_alpha) {}
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META_StateAttribute(osg, BlendFunc,BLENDFUNC);
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/** Return -1 if *this < *rhs, 0 if *this==*rhs, 1 if *this>*rhs. */
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virtual int compare(const StateAttribute& sa) const
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{
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// Check for equal types, then create the rhs variable
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// used by the COMPARE_StateAttribute_Parameter macros below.
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COMPARE_StateAttribute_Types(BlendFunc,sa)
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// Compare each parameter in turn against the rhs.
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COMPARE_StateAttribute_Parameter(_source_factor)
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COMPARE_StateAttribute_Parameter(_destination_factor)
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COMPARE_StateAttribute_Parameter(_source_factor_alpha)
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COMPARE_StateAttribute_Parameter(_destination_factor_alpha)
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return 0; // Passed all the above comparison macros, so must be equal.
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}
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virtual bool getModeUsage(StateAttribute::ModeUsage& usage) const
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{
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usage.usesMode(GL_BLEND);
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return true;
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}
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enum BlendFuncMode {
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DST_ALPHA = GL_DST_ALPHA,
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DST_COLOR = GL_DST_COLOR,
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ONE = GL_ONE,
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ONE_MINUS_DST_ALPHA = GL_ONE_MINUS_DST_ALPHA,
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ONE_MINUS_DST_COLOR = GL_ONE_MINUS_DST_COLOR,
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ONE_MINUS_SRC_ALPHA = GL_ONE_MINUS_SRC_ALPHA,
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ONE_MINUS_SRC_COLOR = GL_ONE_MINUS_SRC_COLOR,
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SRC_ALPHA = GL_SRC_ALPHA,
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SRC_ALPHA_SATURATE = GL_SRC_ALPHA_SATURATE,
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SRC_COLOR = GL_SRC_COLOR,
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CONSTANT_COLOR = GL_CONSTANT_COLOR,
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ONE_MINUS_CONSTANT_COLOR = GL_ONE_MINUS_CONSTANT_COLOR,
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CONSTANT_ALPHA = GL_CONSTANT_ALPHA,
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ONE_MINUS_CONSTANT_ALPHA = GL_ONE_MINUS_CONSTANT_ALPHA,
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ZERO = GL_ZERO
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};
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inline void setFunction( GLenum source, GLenum destination )
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{
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_source_factor = source;
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_destination_factor = destination;
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_source_factor_alpha = source;
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_destination_factor_alpha = destination;
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}
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inline void setFunction( GLenum source_rgb, GLenum destination_rgb, GLenum source_alpha, GLenum destination_alpha )
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{
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_source_factor = source_rgb;
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_destination_factor = destination_rgb;
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_source_factor_alpha = source_alpha;
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_destination_factor_alpha = destination_alpha;
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}
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void setSource(GLenum source) { _source_factor = _source_factor_alpha = source; }
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inline GLenum getSource() const { return _source_factor; }
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void setSourceRGB(GLenum source) { _source_factor = source; }
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inline GLenum getSourceRGB() const { return _source_factor; }
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void setSourceAlpha(GLenum source) { _source_factor_alpha = source; }
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inline GLenum getSourceAlpha() const { return _source_factor_alpha; }
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void setDestination(GLenum destination) { _destination_factor = _destination_factor_alpha = destination; }
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inline GLenum getDestination() const { return _destination_factor; }
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void setDestinationRGB(GLenum destination) { _destination_factor = destination; }
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inline GLenum getDestinationRGB() const { return _destination_factor; }
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void setDestinationAlpha(GLenum destination) { _destination_factor_alpha = destination; }
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inline GLenum getDestinationAlpha() const { return _destination_factor_alpha; }
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virtual void apply(State& state) const;
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/** Encapsulates queries of extension availability, obtains extension
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* function pointers, and provides convenience wrappers for
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* calling extension functions. */
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class OSG_EXPORT Extensions : public osg::Referenced
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{
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public:
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Extensions(unsigned int contextID);
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Extensions(const Extensions& rhs);
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void lowestCommonDenominator(const Extensions& rhs);
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void setupGLExtensions(unsigned int contextID);
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void setBlendFuncSeparateSupported(bool flag) { _isBlendFuncSeparateSupported=flag; }
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bool isBlendFuncSeparateSupported() const { return _isBlendFuncSeparateSupported; }
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void glBlendFuncSeparate(GLenum sfactorRGB,
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GLenum dfactorRGB,
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GLenum sfactorAlpha,
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GLenum dfactorAlpha) const;
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protected:
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~Extensions() {}
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typedef void (GL_APIENTRY * GLBlendFuncSeparateProc) (GLenum sfactorRGB,
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GLenum dfactorRGB,
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GLenum sfactorAlpha,
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GLenum dfactorAlpha);
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bool _isBlendFuncSeparateSupported;
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GLBlendFuncSeparateProc _glBlendFuncSeparate;
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};
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/** Returns the Extensions object for the given context.
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* If createIfNotInitalized is true and the Extensions object doesn't
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* exist, getExtensions() creates it on the given context.
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* Returns NULL if createIfNotInitalized is false and the Extensions
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* object doesn't exist. */
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static Extensions* getExtensions(unsigned int contextID,bool createIfNotInitalized);
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/** setExtensions() allows users to override the extensions across graphics contexts.
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* Typically used when you have different extensions supported across graphics pipes,
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* but need to ensure that they all use the same low common denominator extensions. */
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static void setExtensions(unsigned int contextID,Extensions* extensions);
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protected :
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virtual ~BlendFunc();
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GLenum _source_factor;
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GLenum _destination_factor;
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GLenum _source_factor_alpha;
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GLenum _destination_factor_alpha;
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};
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}
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#endif
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