// Copyright (C) 2002-2012 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"

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,
		//! Texture is mirrored once and then clamped (0..1..0)
		ETC_MIRROR_CLAMP,
		//! Texture is mirrored once and then clamped to edge
		ETC_MIRROR_CLAMP_TO_EDGE,
		//! Texture is mirrored once and then clamped to border
		ETC_MIRROR_CLAMP_TO_BORDER
	};
	static const char* const aTextureClampNames[] = {
			"texture_clamp_repeat",
			"texture_clamp_clamp",
			"texture_clamp_clamp_to_edge",
			"texture_clamp_clamp_to_border",
			"texture_clamp_mirror",
			"texture_clamp_mirror_clamp",
			"texture_clamp_mirror_clamp_to_edge",
			"texture_clamp_mirror_clamp_to_border", 0};


	//! Texture minification filter.
	/** Used when scaling textures down. */
	enum E_TEXTURE_MIN_FILTER {
		//! Nearest-neighbor interpolation.
		ETMINF_NEAREST = 0,
		//! Linear interpolation.
		ETMINF_BILINEAR,
		//! Linear interpolation across mipmaps.
		/** Is equivalent to ETMINF_BILINEAR if mipmaps are disabled.
		Only available as a minification filter since mipmaps are only used
		when scaling down. */
		ETMINF_TRILINEAR,
	};

	//! Texture magnification filter.
	/** Used when scaling textures up. */
	enum E_TEXTURE_MAG_FILTER {
		//! Nearest-neighbor interpolation.
		ETMAGF_NEAREST = 0,
		//! Linear interpolation.
		ETMAGF_BILINEAR,
	};

	//! Struct for holding material parameters which exist per texture layer
	// Note for implementors: Serialization is in CNullDriver
	class SMaterialLayer
	{
	public:
		//! Default constructor
		SMaterialLayer() : Texture(0), TextureWrapU(ETC_REPEAT), TextureWrapV(ETC_REPEAT), TextureWrapW(ETC_REPEAT),
			MinFilter(ETMINF_BILINEAR), MagFilter(ETMAGF_BILINEAR), 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()
		{
			if ( TextureMatrix )
			{
				delete 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
				{
					delete TextureMatrix;
					TextureMatrix = 0;
				}
			}
			else
			{
				if (other.TextureMatrix)
				{
					TextureMatrix = new core::matrix4(*other.TextureMatrix);
				}
				else
					TextureMatrix = 0;
			}
			TextureWrapU = other.TextureWrapU;
			TextureWrapV = other.TextureWrapV;
			TextureWrapW = other.TextureWrapW;
			MinFilter = other.MinFilter;
			MagFilter = other.MagFilter;
			AnisotropicFilter = other.AnisotropicFilter;
			LODBias = other.LODBias;

			return *this;
		}

		//! Gets the texture transformation matrix
		/** \return Texture matrix of this layer. */
		core::matrix4& getTextureMatrix()
		{
			if (!TextureMatrix)
			{
				TextureMatrix = new core::matrix4();
			}
			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
		/** NOTE: Pipelines can ignore this matrix when the 
		texture	is 0.
		\param mat New texture matrix for this layer. */
		void setTextureMatrix(const core::matrix4& mat)
		{
			if (!TextureMatrix)
			{
				TextureMatrix = new core::matrix4(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 ||
				TextureWrapU != b.TextureWrapU ||
				TextureWrapV != b.TextureWrapV ||
				TextureWrapW != b.TextureWrapW ||
				MinFilter != b.MinFilter ||
				MagFilter != b.MagFilter ||
				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); }

		//! Texture
		ITexture* Texture;

		//! Texture Clamp Mode
		/** Values are taken from E_TEXTURE_CLAMP. */
		u8 TextureWrapU:4;
		u8 TextureWrapV:4;
		u8 TextureWrapW:4;

		//! Minification (downscaling) filter
		E_TEXTURE_MIN_FILTER MinFilter;

		//! Magnification (upscaling) filter
		E_TEXTURE_MAG_FILTER MagFilter;

		//! 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;

		//! Sets the MinFilter, MagFilter and AnisotropicFilter properties according
		//! to the three relevant boolean values found in the Minetest settings.
		/** The value of `trilinear` takes precedence over the value of `bilinear`. */
		void setFiltersMinetest(bool bilinear, bool trilinear, bool anisotropic) {
			MinFilter = trilinear ? ETMINF_TRILINEAR :
					(bilinear ? ETMINF_BILINEAR : ETMINF_NEAREST);
			MagFilter = (trilinear || bilinear) ? ETMAGF_BILINEAR : ETMAGF_NEAREST;
			AnisotropicFilter = anisotropic ? 0xFF : 0;
		}

	private:
		friend class SMaterial;

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

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

#endif // __S_MATERIAL_LAYER_H_INCLUDED__