/*******************************************************************************

 Copyright (c) 2009, Charles McGarvey
 All rights reserved.
 
 Redistribution   and   use  in  source  and  binary  forms,  with  or  without
 modification, are permitted provided that the following conditions are met:
 
   * Redistributions  of  source  code  must retain the above copyright notice,
     this list of conditions and the following disclaimer.
   * Redistributions  in binary form must reproduce the above copyright notice,
     this  list of conditions and the following disclaimer in the documentation
     and/or other materials provided with the distribution.
 
 THIS  SOFTWARE  IS  PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 AND  ANY  EXPRESS  OR  IMPLIED  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 DISCLAIMED.  IN  NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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*******************************************************************************/

#ifndef _TILEMAP_HH_
#define _TILEMAP_HH_

/**
 * @file tilemap.hh
 * Small subclass to give some basic tile-mapping functionality to textures.
 */

#include <cassert>

#include <boost/shared_ptr.hpp>

#include "opengl.hh"
#include "texture.hh"


namespace dc {


namespace tile {

/**
 * Possible orientations for texture coordinates.
 */

typedef enum
{
	normal =			0,			///< Normal orientation.
	flip =				1,			///< Flip over a horizontal axis.
	reverse =			2,			///< Flip over a vertical axis.
	flip_and_reverse =	3			///< Flip over both.
} orientation;

} // namespace tile


/**
 * A tilemap is a texture which is meant to be divided into smaller sprites.
 * This class provides all the functionality of a texture and adds some methods
 * to get texture coordinates to individual tiles within the tilemap.  For
 * simplicity, this class assumes square tiles.
 */

class tilemap : public texture
{
public:
	tilemap(const std::string& filePath, bool keepInMemory = false,
			unsigned tilesU = 1, unsigned tilesV = 1)
		: texture(filePath, keepInMemory), tilesU_(tilesU), tilesV_(tilesV) {}


	/**
	 * Set the number of rows and columns of square tiles.
	 * @param tilesU Columns of tiles.
	 * @param tilesV Rows of tiles.
	 */

	void setTileDimensions(unsigned tilesU, unsigned tilesV)
	{
		assert(tilesU != 0 && tilesV != 0);
		tilesU_ = tilesU;
		tilesV_ = tilesV;
	}


	/**
	 * Calculate texture coordinates for a tile at a certain index.  Tiles are
	 * indexed start with zero as the to-left tile and moving across, then down.
	 * @param index The tile index.
	 * @param coords An array of floats where the texture coordinates will be
	 * stored after this call.  The first coordinate (u,v) will be in the first
	 * two places and so on until all four coordinates are stored, therefore
	 * requiring enough room for an array of eight floats.  The winding of the
	 * coordinates is always counter-clockwise (the GL default).
	 */

	void getTileCoords(unsigned index, float coords[8])
	{
		assert(index < tilesU_ * tilesV_);

		float w = 1.0 / float(tilesU_);
		float h = 1.0 / float(tilesV_);

		coords[0] = float(index % tilesU_) * w;
		coords[1] = (float(tilesV_ - 1) - float(index / tilesU_)) * h;
		coords[2] = coords[0] + w;
		coords[3] = coords[1];
		coords[4] = coords[2];
		coords[5] = coords[1] + h;
		coords[6] = coords[0];
		coords[7] = coords[5];
	}

	/**
	 * This version let's you specify an orientation that will be reflected in
	 * the texture coordinates.  This allows you to easily map a texture
	 * backwards or upside-down.
	 * @param what The orientation; can be flip, reverse, or flip_and_reverse.
	 */

	void getTileCoords(unsigned index, float coords[8], tile::orientation what)
	{
		getTileCoords(index, coords);

		if (what & tile::flip)
		{
			coords[1] = coords[5];
			coords[5] = coords[3];
			coords[3] = coords[7];
			coords[7] = coords[5];
		}
		if (what & tile::reverse)
		{
			coords[0] = coords[2];
			coords[2] = coords[6];
			coords[4] = coords[6];
			coords[6] = coords[0];
		}
	}

private:
	unsigned tilesU_;
	unsigned tilesV_;
};


} // namespace dc

#endif // _TILEMAP_HH_