TexEnvCombine

/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield 
 *
 * This library is open source and may be redistributed and/or modified under  
 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or 
 * (at your option) any later version.  The full license is in LICENSE file
 * included with this distribution, and on the openscenegraph.org website.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 * OpenSceneGraph Public License for more details.
*/

#ifndef OSG_TEXENVCOMBINE
#define OSG_TEXENVCOMBINE 1

#include <osg/TexEnv>
#include <osg/Vec3>
#include <osg/Vec4>

// If not defined by gl.h use the definition found in:
// http://oss.sgi.com/projects/ogl-sample/registry/ARB/texture_env_combine.txt
#ifndef GL_ARB_texture_env_combine
#define GL_COMBINE_ARB                                     0x8570
#define GL_COMBINE_RGB_ARB                                 0x8571
#define GL_COMBINE_ALPHA_ARB                               0x8572
#define GL_SOURCE0_RGB_ARB                                 0x8580
#define GL_SOURCE1_RGB_ARB                                 0x8581
#define GL_SOURCE2_RGB_ARB                                 0x8582
#define GL_SOURCE0_ALPHA_ARB                               0x8588
#define GL_SOURCE1_ALPHA_ARB                               0x8589
#define GL_SOURCE2_ALPHA_ARB                               0x858A
#define GL_OPERAND0_RGB_ARB                                0x8590
#define GL_OPERAND1_RGB_ARB                                0x8591
#define GL_OPERAND2_RGB_ARB                                0x8592
#define GL_OPERAND0_ALPHA_ARB                              0x8598
#define GL_OPERAND1_ALPHA_ARB                              0x8599
#define GL_OPERAND2_ALPHA_ARB                              0x859A
#define GL_RGB_SCALE_ARB                                   0x8573
#define GL_ADD_SIGNED_ARB                                  0x8574
#define GL_INTERPOLATE_ARB                                 0x8575
#define GL_SUBTRACT_ARB                                    0x84E7
#define GL_CONSTANT_ARB                                    0x8576
#define GL_PRIMARY_COLOR_ARB                               0x8577
#define GL_PREVIOUS_ARB                                    0x8578
#endif

#ifndef GL_ARB_texture_env_dot3
#define GL_DOT3_RGB_ARB                                    0x86AE
#define GL_DOT3_RGBA_ARB                                   0x86AF
#endif

#ifndef GL_TEXTURE0
#define GL_TEXTURE0 0x84C0
#endif

namespace osg {

/** TexEnvCombine encapsulates the OpenGL glTexEnvCombine (texture
  * environment) state. */
class OSG_EXPORT TexEnvCombine : public StateAttribute
{
    public :

        TexEnvCombine();
        
        /** Copy constructor using CopyOp to manage deep vs shallow copy. */
        TexEnvCombine(const TexEnvCombine& texenv,const CopyOp& copyop=CopyOp::SHALLOW_COPY):
            StateAttribute(texenv,copyop),
            _needsTexEnvCrossbar(texenv._needsTexEnvCrossbar),
            _combine_RGB(texenv._combine_RGB),
            _combine_Alpha(texenv._combine_Alpha),
            _source0_RGB(texenv._source0_RGB),
            _source1_RGB(texenv._source1_RGB),
            _source2_RGB(texenv._source2_RGB),
            _source0_Alpha(texenv._source0_Alpha),
            _source1_Alpha(texenv._source1_Alpha),
            _source2_Alpha(texenv._source2_Alpha),
            _operand0_RGB(texenv._operand0_RGB),
            _operand1_RGB(texenv._operand1_RGB),
            _operand2_RGB(texenv._operand2_RGB),
            _operand0_Alpha(texenv._operand0_Alpha),
            _operand1_Alpha(texenv._operand1_Alpha),
            _operand2_Alpha(texenv._operand2_Alpha),
            _scale_RGB(texenv._scale_RGB),
            _scale_Alpha(texenv._scale_Alpha),
            _constantColor(texenv._constantColor) {}


        META_StateAttribute(osg, TexEnvCombine, TEXENV);


        virtual bool isTextureAttribute() const { return true; }

        /** Return -1 if *this < *rhs, 0 if *this==*rhs, 1 if *this>*rhs. */
        virtual int compare(const StateAttribute& sa) const
        {
            // Check for equal types, then create the rhs variable
            // used by the COMPARE_StateAttribute_parameter macros below.
            COMPARE_StateAttribute_Types(TexEnvCombine,sa)

            // Compare each parameter in turn against the rhs.
            COMPARE_StateAttribute_Parameter(_needsTexEnvCrossbar)
            COMPARE_StateAttribute_Parameter(_combine_RGB)
            COMPARE_StateAttribute_Parameter(_combine_Alpha)
            COMPARE_StateAttribute_Parameter(_source0_RGB)
            COMPARE_StateAttribute_Parameter(_source1_RGB)
            COMPARE_StateAttribute_Parameter(_source2_RGB)
            COMPARE_StateAttribute_Parameter(_source0_Alpha)
            COMPARE_StateAttribute_Parameter(_source1_Alpha)
            COMPARE_StateAttribute_Parameter(_source2_Alpha)
            COMPARE_StateAttribute_Parameter(_operand0_RGB)
            COMPARE_StateAttribute_Parameter(_operand1_RGB)
            COMPARE_StateAttribute_Parameter(_operand2_RGB)
            COMPARE_StateAttribute_Parameter(_operand0_Alpha)
            COMPARE_StateAttribute_Parameter(_operand1_Alpha)
            COMPARE_StateAttribute_Parameter(_operand2_Alpha)
            COMPARE_StateAttribute_Parameter(_scale_RGB)
            COMPARE_StateAttribute_Parameter(_scale_Alpha)
            COMPARE_StateAttribute_Parameter(_constantColor)

            return 0; // Passed all the above comparison macros, so must be equal.
        }


        enum CombineParam
        {
            REPLACE         = GL_REPLACE,
            MODULATE        = GL_MODULATE,
            ADD             = GL_ADD,
            ADD_SIGNED      = GL_ADD_SIGNED_ARB,
            INTERPOLATE     = GL_INTERPOLATE_ARB,
            SUBTRACT        = GL_SUBTRACT_ARB,
            DOT3_RGB        = GL_DOT3_RGB_ARB,
            DOT3_RGBA       = GL_DOT3_RGBA_ARB
        };

        void setCombine_RGB(GLint cm);
        void setCombine_Alpha(GLint cm);

        GLint getCombine_RGB() const { return _combine_RGB; }
        GLint getCombine_Alpha() const { return _combine_Alpha; }
        
        enum SourceParam
        {
            CONSTANT        = GL_CONSTANT_ARB,
            PRIMARY_COLOR   = GL_PRIMARY_COLOR_ARB,
            PREVIOUS        = GL_PREVIOUS_ARB,
            TEXTURE         = GL_TEXTURE,
            TEXTURE0        = GL_TEXTURE0,
            TEXTURE1        = GL_TEXTURE0+1,
            TEXTURE2        = GL_TEXTURE0+2,
            TEXTURE3        = GL_TEXTURE0+3,
            TEXTURE4        = GL_TEXTURE0+4,
            TEXTURE5        = GL_TEXTURE0+5,
            TEXTURE6        = GL_TEXTURE0+6,
            TEXTURE7        = GL_TEXTURE0+7
        };
        
        void setSource0_RGB(GLint sp);
        void setSource1_RGB(GLint sp);
        void setSource2_RGB(GLint sp);
        
        void setSource0_Alpha(GLint sp);
        void setSource1_Alpha(GLint sp);
        void setSource2_Alpha(GLint sp);

        GLint getSource0_RGB() const { return _source0_RGB; }
        GLint getSource1_RGB() const { return _source1_RGB; }
        GLint getSource2_RGB() const { return _source2_RGB; }
        
        GLint getSource0_Alpha() const { return _source0_Alpha; }
        GLint getSource1_Alpha() const { return _source1_Alpha; }
        GLint getSource2_Alpha() const { return _source2_Alpha; }

        enum OperandParam
        {
            SRC_COLOR           = GL_SRC_COLOR,
            ONE_MINUS_SRC_COLOR = GL_ONE_MINUS_SRC_COLOR,
            SRC_ALPHA           = GL_SRC_ALPHA,
            ONE_MINUS_SRC_ALPHA = GL_ONE_MINUS_SRC_ALPHA
        };
        
        void setOperand0_RGB(GLint op);
        void setOperand1_RGB(GLint op);
        void setOperand2_RGB(GLint op);
        
        void setOperand0_Alpha(GLint op);
        void setOperand1_Alpha(GLint op);
        void setOperand2_Alpha(GLint op);

        GLint getOperand0_RGB() const { return _operand0_RGB; }
        GLint getOperand1_RGB() const { return _operand1_RGB; }
        GLint getOperand2_RGB() const { return _operand2_RGB; }
        
        GLint getOperand0_Alpha() const { return _operand0_Alpha; }
        GLint getOperand1_Alpha() const { return _operand1_Alpha; }
        GLint getOperand2_Alpha() const { return _operand2_Alpha; }


        void setScale_RGB(float scale);
        void setScale_Alpha(float scale);

        float getScale_RGB() const { return _scale_RGB; }
        float getScale_Alpha() const { return _scale_Alpha; }

        void setConstantColor( const Vec4& color ) { _constantColor = color; }
        const Vec4& getConstantColor() const { return _constantColor; }

        /** Set the constant color attribute to the given light direction
          * for use with DOT3 combine operation. */
        void setConstantColorAsLightDirection(const Vec3& direction)
        {
            _constantColor.set((direction.x()+1.0f)*0.5f,(direction.y()+1.0f)*0.5f,(direction.z()+1.0f)*0.5f,1.0f);
        }

        Vec3 getConstantColorAsLightDirection() const
        {
            return Vec3(_constantColor.x()*2.0f-1.0f, _constantColor.y()*2.0f-1.0f, _constantColor.z()*2.0f-1.0f);
        }

        virtual void apply(State& state) const;

    protected :

        virtual ~TexEnvCombine();

        inline bool needsTexEnvCombiner(GLint value) const
        {
            switch(value)
            {
                case(CONSTANT):
                case(PRIMARY_COLOR):
                case(PREVIOUS):
                case(TEXTURE):
                    return false;
            }
            return true;
        }

        void computeNeedForTexEnvCombiners()
        {
            _needsTexEnvCrossbar = (needsTexEnvCombiner(_source0_RGB) ||
                                    needsTexEnvCombiner(_source1_RGB) ||
                                    needsTexEnvCombiner(_source2_RGB) ||
                                    needsTexEnvCombiner(_source0_Alpha) ||
                                    needsTexEnvCombiner(_source1_Alpha) ||
                                    needsTexEnvCombiner(_source2_Alpha)); 
        }
        

        


        bool            _needsTexEnvCrossbar;

        GLint           _combine_RGB;
        GLint           _combine_Alpha;
    
        GLint           _source0_RGB;
        GLint           _source1_RGB;
        GLint           _source2_RGB;
        
        GLint           _source0_Alpha;
        GLint           _source1_Alpha;
        GLint           _source2_Alpha;


        GLint           _operand0_RGB;
        GLint           _operand1_RGB;
        GLint           _operand2_RGB;
        
        GLint           _operand0_Alpha;
        GLint           _operand1_Alpha;
        GLint           _operand2_Alpha;


        float           _scale_RGB;
        float           _scale_Alpha;
        
        osg::Vec4       _constantColor;

};

}

#endif