/** Helper structures for the Collada loader */

/*
Open Asset Import Library (ASSIMP)
----------------------------------------------------------------------

Copyright (c) 2006-2008, ASSIMP Development Team
All rights reserved.

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* Redistributions in binary form must reproduce the above
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
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*/

#ifndef AI_COLLADAHELPER_H_INC
#define AI_COLLADAHELPER_H_INC

namespace Assimp
{
namespace Collada
{

/** Transformation types that can be applied to a node */
enum TransformType
{
	TF_LOOKAT,
	TF_ROTATE,
	TF_TRANSLATE,
	TF_SCALE,
	TF_SKEW,
	TF_MATRIX
};

/** Contains all data for one of the different transformation types */
struct Transform
{
	TransformType mType;
	float f[16]; ///< Interpretation of data depends on the type of the transformation 
};

/** A reference to a mesh inside a node, including materials assigned to the various subgroups */
struct MeshInstance
{
	std::string mMesh; ///< ID of the mesh
	std::map<std::string, std::string> mMaterials; ///< Map of materials by the subgroup ID they're applied to
};

/** A node in a scene hierarchy */
struct Node
{
	std::string mName;
	std::string mID;
	Node* mParent;
	std::vector<Node*> mChildren;

	/** Operations in order to calculate the resulting transformation to parent. */
	std::vector<Transform> mTransforms;

	std::vector<MeshInstance> mMeshes; ///< Meshes at this node

	Node() { mParent = NULL; }
	~Node() { for( std::vector<Node*>::iterator it = mChildren.begin(); it != mChildren.end(); ++it) delete *it; }
};

/** Data source array */
struct Data
{
	std::vector<float> mValues;
};

/** Accessor to a data array */
struct Accessor
{
	size_t mCount;   // in number of objects
	size_t mOffset;  // in number of values
	size_t mStride;  // Stride in number of values
	std::vector<std::string> mParams; // names of the data streams in the accessors. Empty string tells to ignore. 
	size_t mSubOffset[4]; // Suboffset inside the object for the common 4 elements. For a vector, thats XYZ, for a color RGBA and so on.
						  // For example, SubOffset[0] denotes which of the values inside the object is the vector X component.
	std::string mSource;   // URL of the source array
	mutable const Data* mData; // Pointer to the source array, if resolved. NULL else

	Accessor() 
	{ 
		mCount = 0; mOffset = 0; mStride = 0; mData = NULL; 
		mSubOffset[0] = mSubOffset[1] = mSubOffset[2] = mSubOffset[3] = 0;
	}
};

/** A single face in a mesh */
struct Face
{
	std::vector<size_t> mIndices;
};

/** Different types of input data to a vertex or face */
enum InputType
{
	IT_Invalid,
	IT_Vertex,  // special type for per-index data referring to the <vertices> element carrying the per-vertex data.
	IT_Position,
	IT_Normal,
	IT_Texcoord,
	IT_Color
};

/** An input channel for mesh data, referring to a single accessor */
struct InputChannel
{
	InputType mType;      // Type of the data
	size_t mIndex;		  // Optional index, if multiple sets of the same data type are given
	size_t mOffset;       // Index offset in the indices array of per-face indices. Don't ask, can't explain that any better.
	std::string mAccessor; // ID of the accessor where to read the actual values from.
	mutable const Accessor* mResolved; // Pointer to the accessor, if resolved. NULL else

	InputChannel() { mType = IT_Invalid; mIndex = 0; mOffset = 0; mResolved = NULL; }
};

/** Subset of a mesh with a certain material */
struct SubMesh
{
	std::string mMaterial; ///< subgroup identifier
	size_t mNumFaces; ///< number of faces in this submesh
};

/** Contains data for a single mesh */
struct Mesh
{
	std::string mVertexID; // just to check if there's some sophisticated addressing involved... which we don't support, and therefore should warn about.
	std::vector<InputChannel> mPerVertexData; // Vertex data addressed by vertex indices

	// actual mesh data, assembled on encounter of a <p> element. Verbose format, not indexed
	std::vector<aiVector3D> mPositions;
	std::vector<aiVector3D> mNormals;
	std::vector<aiVector2D> mTexCoords[AI_MAX_NUMBER_OF_TEXTURECOORDS];
	std::vector<aiColor4D> mColors[AI_MAX_NUMBER_OF_COLOR_SETS];

	// Faces. Stored are only the number of vertices for each face. 1 == point, 2 == line, 3 == triangle, 4+ == poly
	std::vector<size_t> mFaceSize;

	// Submeshes in this mesh, each with a given material
	std::vector<SubMesh> mSubMeshes;
};

/** Which type of primitives the ReadPrimitives() function is going to read */
enum PrimitiveType
{
	Prim_Invalid,
	Prim_Lines,
	Prim_LineStrip,
	Prim_Triangles,
	Prim_TriStrips,
	Prim_TriFans,
	Prim_Polylist,
	Prim_Polygon
};

/** A collada material. Pretty much the only member is a reference to an effect. */
struct Material
{
	std::string mEffect;
};

/** Type of the effect param */
enum ParamType
{
	Param_Sampler,
	Param_Surface
};

/** A param for an effect. Might be of several types, but they all just refer to each other, so I summarize them */
struct EffectParam
{
	ParamType mType;
	std::string mReference; // to which other thing the param is referring to. 
};

/** Shading type supported by the standard effect spec of Collada */
enum ShadeType
{
	Shade_Invalid,
	Shade_Constant,
	Shade_Lambert,
	Shade_Phong,
	Shade_Blinn
};


/** A collada effect. Can contain about anything according to the Collada spec, but we limit our version to a reasonable subset. */
struct Effect
{
	ShadeType mShadeType;
	aiColor4D mEmissive, mAmbient, mDiffuse, mSpecular;
	aiColor4D mReflective, mRefractive;
	std::string mTexEmissive, mTexAmbient, mTexDiffuse, mTexSpecular;
	float mShininess, mRefractIndex;
	float mReflectivity, mRefractivity;

	// local params referring to each other by their SID
	typedef std::map<std::string, Collada::EffectParam> ParamLibrary;
	ParamLibrary mParams;
	
	Effect() : mEmissive( 0, 0, 0, 1), mAmbient( 0.1f, 0.1f, 0.1f, 1),
		mDiffuse( 0.6f, 0.6f, 0.6f, 1), mSpecular( 0.4f, 0.4f, 0.4f, 1),
		mReflective( 0, 0, 0, 0), mRefractive( 0, 0, 0, 0)
	{ 
		mShadeType = Shade_Phong; 
		mShininess = 10.0f;
		mRefractIndex = 1.0f;
		mReflectivity = 0.0f;
		mRefractivity = 0.0f;
	}
};

/** An image, meaning texture */
struct Image
{
	std::string mFileName;
};

} // end of namespace Collada
} // end of namespace Assimp

#endif // AI_COLLADAHELPER_H_INC