#ifndef _SKYPREETHAM_H__
#define _SKYPREETHAM_H__

#include "common.h"
#include "ShaderProgram.h"



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

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

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

	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,
						 bool scaleToRange) const;

	void InitCG();


protected:

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


	//////////

	/*	FEffect*		mEffect;

	FEffect*		mSunEffect;
	FTexture2D*		mSunTexture;
	FVertexBuffer*	mSunQuad;
	*/

	CHCDemoEngine::SceneEntity *mSkyDome;

	/// the turbidity of the sky
	float mTurbidity;

	CHCDemoEngine::ShaderProgram *mSkyVtxProgram;
	CHCDemoEngine::ShaderProgram *mSkyFragProgram;
};

#endif //_SKYPREETHAM_H__