/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2005 Robert Osfield 
 * Copyright (C) 2003-2005 3Dlabs Inc. Ltd.
 *
 * This application is open source and may be redistributed and/or modified   
 * freely and without restriction, both in commericial and non commericial
 * applications, as long as this copyright notice is maintained.
 * 
 * This application 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.
*/

/* file:	include/osg/Program
 * author:	Mike Weiblen 2005-02-20
*/

// NOTICE: This code is CLOSED during construction and/or renovation!
// It is in active development, so DO NOT yet use in application code.
// This notice will be removed when the code is open for business.
// For development plan and status see:
// http://www.openscenegraph.org/index.php?page=Community.DevelopmentWork


#ifndef OSG_SHADER
#define OSG_SHADER 1

#include <osg/Program>

namespace osg {

///////////////////////////////////////////////////////////////////////////
/** osg::Shader is an application-level abstraction of an OpenGL glShader.
  * It is a container to load the shader source code text and manage its
  * compilation.
  * A Shader may be attached to more than one osg::Program.
  * Shader will automatically manage per-context instancing of the
  * internal objects, if that is necessary for a particular display
  * configuration.
  */

class SG_EXPORT Shader : public osg::Referenced
{
    public:

	enum Type {
	    VERTEX = GL_VERTEX_SHADER,
	    FRAGMENT = GL_FRAGMENT_SHADER,
	};

        Shader( Type type, const char* sourceText = 0 );

        /** Copy constructor using CopyOp to manage deep vs shallow copy.*/
        Shader(const Shader& rhs, const osg::CopyOp& copyop=osg::CopyOp::SHALLOW_COPY);

        int compare(const Shader& rhs) const;

        // data access methods.

	/** Load the Shader's source code text from a string. */
	void setShaderSource( const char* sourceText );

	/** Load the Shader's source code text from a file. */
	bool loadShaderSourceFromFile( const char* fileName );

	/** Query the shader's source code text */
	inline const std::string& getShaderSource() const { return _shaderSource; }

	/** Get the Shader type as an enum. */
	inline Type getType() const { return _type; }

	/** Get the Shader type as a descriptive string. */
	const char* getTypename() const;

        /** Mark us as "dirty" and in need of recompilation */
        void dirtyShader();        

        /** Mark internal GL glShader for deletion.
	  * Deletion requests are queued until they can be executed
	  * in the proper GL context. */
        static void deleteShader(unsigned int contextID, GLuint shader);

	/** Perform a recompilation of all our PCSOs */
	void compileShader(unsigned int contextID) const;

	/** For a given GL context, attach a glShader to a glProgram */
	void attachShader(unsigned int contextID, GLuint program) const;

	/** An annotation/comment for use by the application */
	void setComment( const std::string& comment ) { _comment = comment; }
	void setComment( const char* comment ) { _comment = comment; }
	const std::string& getComment() const { return _comment; };


    protected:
	/** PCSO is an OSG-internal encapsulation of glShader per-GL context. */
	class PerContextShaderObj : public osg::Referenced
	{
	    public:
		PerContextShaderObj(const Shader* shader, unsigned int contextID);
		PerContextShaderObj(const PerContextShaderObj& rhs);

		const GLuint getHandle() {return _glShaderHandle;}

		bool isDirty() const {return _dirty;}
		void markAsDirty() {_dirty = true; }
		void compileShader();

		/** Attach our glShader to a glProgram */
		void attachShader(GLuint program) const;

	    protected:	/*methods*/
		PerContextShaderObj();
		~PerContextShaderObj();

	    protected:	/*data*/
		/** Pointer to our parent Shader */
		const Shader* _shader;
		/** Pointer to this context's extension functions. */
		osg::ref_ptr<GL2Extensions> _extensions;
		/** Handle to the actual glShader. */
		GLuint _glShaderHandle;
		/** Do we need to be recompiled? */
		bool _dirty;
		const unsigned int _contextID;
	};

    protected:	/*methods*/
        virtual ~Shader();
        PerContextShaderObj* getPCSO(unsigned int contextID) const;

	friend void Program::addShader( Shader* shader );	// to access addProgObjRef()
	void addProgObjRef( Program* program );

    protected:	/*data*/
	const Type _type;
	std::string _comment;
	std::string _shaderSource;
	/** list of Programs that this Shader is attached to */
	std::vector< ProgramPtr > _programList;
        mutable osg::buffered_value< osg::ref_ptr<PerContextShaderObj> > _pcsoList;

    private:
        Shader();	// disallowed
        Shader& operator=(const Shader&);	// disallowed
};


}

#endif

/*EOF*/