#ifndef _SKYPREETHAM_H__
#define _SKYPREETHAM_H__

#include "glInterface.h"
#include "common.h"
#include <Cg/cg.h>
#include <Cg/cgGL.h>


namespace CHCDemoEngine{
class Vector3;
class SceneEntity;
class RenderState;
class Camera;
}

class SkyPreetham
{
public:
	/// Constructor taking sky turbitity as parameter and the sky dome geometry
	SkyPreetham(float turbitity, CHCDemoEngine::SceneEntity *skyDome);
	virtual ~SkyPreetham();

	void RenderSkyDome(const CHCDemoEngine::Vector3 &sunDir, CHCDemoEngine::Camera *camera, CHCDemoEngine::RenderState *state);

	static void Init(CGcontext context);

	void ComputeFactors(const CHCDemoEngine::Vector3 &sunDir, 
		                CHCDemoEngine::Vector3 &zenithColor, 
						std::vector<CHCDemoEngine::Vector3> &ABCDE, 
						std::pair<float, float> &sunThetha) const;

	void ComputeSunColor(const CHCDemoEngine::Vector3 &sunDir, CHCDemoEngine::Vector3 &ambient, CHCDemoEngine::Vector3 &diffuse) const;


protected:

	void RenderSunDisk(const CHCDemoEngine::Vector3 &lightDir, CHCDemoEngine::Camera *camera);
	void CreateSunQuad();


	/// Members.
/*	FEffect*		mEffect;

	FEffect*		mSunEffect;
	FTexture2D*		mSunTexture;
	FVertexBuffer*	mSunQuad;
*/
	CHCDemoEngine::SceneEntity *mSkyDome;

	float mTurbidity;
};

#endif //_SKYPREETHAM_H__