TwoSidedSurfaceShader.h

/***********************************************************************
TwoSidedSurfaceShader - Class to simulate OpenGL two-sided lighting
without the ridiculous and arbitrary performance penalty it incurs on
newer Nvidia Geforce graphics cards (shame on you, Nvidia!).
Copyright (c) 2012-2023 Oliver Kreylos

This file is part of the 3D Data Visualizer (Visualizer).

The 3D Data Visualizer is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as published
by the Free Software Foundation; either version 2 of the License, or (at
your option) any later version.

The 3D Data Visualizer 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 GNU
General Public License for more details.

You should have received a copy of the GNU General Public License along
with the 3D Data Visualizer; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
***********************************************************************/

#ifndef TWOSIDEDSURFACESHADER_INCLUDED
#define TWOSIDEDSURFACESHADER_INCLUDED

#include <Threads/Spinlock.h>
#include <GL/GLObject.h>
#include <GL/GLShader.h>

/* Forward declarations: */
class GLLightTracker;
class GLClipPlaneTracker;
namespace SceneGraph {
class GLRenderState;
}

class TwoSidedSurfaceShader:public GLObject
	{
	struct DataItem:public GLObject::DataItem
		{
		/* Elements: */
		public:
		GLShader shader; // The GLSL shader object containing the linked shader program
		unsigned int lightTrackerVersion; // Version number of the OpenGL lighting state for which the shader program was built
		unsigned int clipPlaneTrackerVersion; // Version number of the OpenGL clipping plane state for which the shader program was built
		
		/* Constructors and destructors: */
		DataItem(void);
		virtual ~DataItem(void);
		
		/* Methods: */
		void buildShader(GLLightTracker& lt,GLClipPlaneTracker& cpt); // Rebuilds the shader program according to the given OpenGL state trackers' current states
		};
	
	/* Elements: */
	private:
	static Threads::Spinlock theShaderMutex; // Mutex protecting the shared shader object and its reference counter
	static unsigned int theShaderRefCount; // Reference counter for the shared shader object
	static TwoSidedSurfaceShader* theShader; // Pointer to the shared two-sided surface shader object
	
	/* Constructors and destructors: */
	public:
	static bool isSupported(GLContextData& contextData); // Returns true if simulated two-sided lighting is supported in the given OpenGL context
	static TwoSidedSurfaceShader* acquireShader(void); // Returns a pointer to a shared two-sided surface shader
	static void releaseShader(TwoSidedSurfaceShader* shader); // Releases the given two-sided surface shader
	private:
	TwoSidedSurfaceShader(void); // Creates a two-sided surface shader
	virtual ~TwoSidedSurfaceShader(void); // Destroys the shader
	
	/* Methods from class GLObject: */
	public:
	virtual void initContext(GLContextData& contextData) const;
	
	/* New methods: */
	void set(SceneGraph::GLRenderState& renderState) const; // Sets up two-sided surface shading for the given render state
	};

#endif