// Copyright (C) 2002-2009 Nikolaus Gebhardt
// This file is part of the "Irrlicht Engine".
// For conditions of distribution and use, see copyright notice in irrlicht.h

#ifndef __S_MATERIAL_LAYER_H_INCLUDED__
#define __S_MATERIAL_LAYER_H_INCLUDED__

#include "matrix4.h"
#include "irrAllocator.h"

namespace irr
{
namespace video
{
	class ITexture;

	//! Texture coord clamp mode outside [0.0, 1.0]
	enum E_TEXTURE_CLAMP
	{
		//! Texture repeats
		ETC_REPEAT = 0,
		//! Texture is clamped to the last pixel
		ETC_CLAMP,
		//! Texture is clamped to the edge pixel
		ETC_CLAMP_TO_EDGE,
		//! Texture is clamped to the border pixel (if exists)
		ETC_CLAMP_TO_BORDER,
		//! Texture is alternatingly mirrored (0..1..0..1..0..)
		ETC_MIRROR
	};
	static const char* const aTextureClampNames[] = {
			"texture_clamp_repeat",
			"texture_clamp_clamp",
			"texture_clamp_clamp_to_edge",
			"texture_clamp_clamp_to_border",
			"texture_clamp_mirror", 0};

	//! Struct for holding material parameters which exist per texture layer
	class SMaterialLayer
	{
	public:
		//! Default constructor
		SMaterialLayer()
			: Texture(0),
				TextureWrap(ETC_REPEAT),
				BilinearFilter(true),
				TrilinearFilter(false),
				AnisotropicFilter(0),
				LODBias(0),
				TextureMatrix(0)
			{}

		//! Copy constructor
		/** \param other Material layer to copy from. */
		SMaterialLayer(const SMaterialLayer& other)
		{
			// This pointer is checked during assignment
			TextureMatrix = 0;
			*this = other;
		}

		//! Destructor
		~SMaterialLayer()
		{
			MatrixAllocator.destruct(TextureMatrix);
			MatrixAllocator.deallocate(TextureMatrix); 
		}

		//! Assignment operator
		/** \param other Material layer to copy from.
		\return This material layer, updated. */
		SMaterialLayer& operator=(const SMaterialLayer& other)
		{
			// Check for self-assignment!
			if (this == &other)
				return *this;

			Texture = other.Texture;
			if (TextureMatrix)
			{
				if (other.TextureMatrix)
					*TextureMatrix = *other.TextureMatrix;
				else
				{
					MatrixAllocator.destruct(TextureMatrix);
					MatrixAllocator.deallocate(TextureMatrix); 
					TextureMatrix = 0;
				}
			}
			else
			{
				if (other.TextureMatrix)
				{
					TextureMatrix = MatrixAllocator.allocate(1);
					MatrixAllocator.construct(TextureMatrix,*other.TextureMatrix);
				}
				else
					TextureMatrix = 0;
			}
			TextureWrap = other.TextureWrap;
			BilinearFilter = other.BilinearFilter;
			TrilinearFilter = other.TrilinearFilter;
			AnisotropicFilter = other.AnisotropicFilter;
			LODBias = other.LODBias;

			return *this;
		}

		//! Texture
		ITexture* Texture;

		//! Texture Clamp Mode
		u8 TextureWrap;

		//! Is bilinear filtering enabled? Default: true
		bool BilinearFilter:1;

		//! Is trilinear filtering enabled? Default: false
		/** If the trilinear filter flag is enabled,
		the bilinear filtering flag is ignored. */
		bool TrilinearFilter:1;

		//! Is anisotropic filtering enabled? Default: 0, disabled
		/** In Irrlicht you can use anisotropic texture filtering
		in conjunction with bilinear or trilinear texture
		filtering to improve rendering results. Primitives
		will look less blurry with this flag switched on. The number gives 
		the maximal anisotropy degree, and is often in the range 2-16. 
		Value 1 is equivalent to 0, but should be avoided. */
		u8 AnisotropicFilter;

		//! Bias for the mipmap choosing decision.
		/** This value can make the textures more or less blurry than with the
		default value of 0. The value (divided by 8.f) is added to the mipmap level
		chosen initially, and thus takes a smaller mipmap for a region
		if the value is positive. */
		s8 LODBias;

		//! Gets the texture transformation matrix
		/** \return Texture matrix of this layer. */
		core::matrix4& getTextureMatrix()
		{
			if (!TextureMatrix)
			{
				TextureMatrix = MatrixAllocator.allocate(1);
				MatrixAllocator.construct(TextureMatrix,core::IdentityMatrix);
			}
			return *TextureMatrix;
		}

		//! Gets the immutable texture transformation matrix
		/** \return Texture matrix of this layer. */
		const core::matrix4& getTextureMatrix() const
		{
			if (TextureMatrix)
				return *TextureMatrix;
			else
				return core::IdentityMatrix;
		}

		//! Sets the texture transformation matrix to mat
		/** \param mat New texture matrix for this layer. */
		void setTextureMatrix(const core::matrix4& mat)
		{
			if (!TextureMatrix)
			{
				TextureMatrix = MatrixAllocator.allocate(1);
				MatrixAllocator.construct(TextureMatrix,mat);
			}
			else
				*TextureMatrix = mat;
		}

		//! Inequality operator
		/** \param b Layer to compare to.
		\return True if layers are different, else false. */
		inline bool operator!=(const SMaterialLayer& b) const
		{
			bool different =
				Texture != b.Texture ||
				TextureWrap != b.TextureWrap ||
				BilinearFilter != b.BilinearFilter ||
				TrilinearFilter != b.TrilinearFilter ||
				AnisotropicFilter != b.AnisotropicFilter ||
				LODBias != b.LODBias;
			if (different)
				return true;
			else
				different |= (TextureMatrix != b.TextureMatrix) &&
					TextureMatrix && b.TextureMatrix &&
					(*TextureMatrix != *(b.TextureMatrix));
			return different;
		}

		//! Equality operator
		/** \param b Layer to compare to.
		\return True if layers are equal, else false. */
		inline bool operator==(const SMaterialLayer& b) const
		{ return !(b!=*this); }

	private:
		friend class SMaterial;
		irr::core::irrAllocator<irr::core::matrix4> MatrixAllocator;

		//! Texture Matrix
		/** Do not access this element directly as the internal
		ressource management has to cope with Null pointers etc. */
		core::matrix4* TextureMatrix;
	};

} // end namespace video
} // end namespace irr

#endif // __S_MATERIAL_LAYER_H_INCLUDED__
