/**

 * @file  sampler.h

 * @brief Screen sample generation and image reconstruction

 *

 * This file is part of Pyrit Ray Tracer.

 *

 * Copyright 2008  Radek Brich

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

 * THE SOFTWARE.

 */

#ifndef SAMPLER_H

#define SAMPLER_H

#include "common.h"

#include "vector.h"

#include "pixmap.h"

using namespace std;

/**

 * A structure containing sample's coordinates.

 */

class Sample

{

public:

	//@{

	/**

	 * Generated coordinates.

	 *

	 * These are coordinates for use by Camera.

	 * Middle of the screen plane has [0,0],

	 * top of the screen has y=-0.5, left pixels has x<0

	 * and the rest of samples are aligned to regular grid,

	 * so the vertical size is always one and horizontal size

	 * can be wider depending on aspect ratio.

	 */

	Float x,y;

	//@}

	//@{

	/**

	 * Auxiliary coordinates used internally by sampler.

	 *

	 * Screen coordinates sx, sy are integer coordinates of screen pixels,

	 * osa_samp is used by oversampling to remember current sample.

	 */

	int sx,sy,osa_samp;

	//@}

};

/**

 * A abstract sampler.

 *

 * It generates screen samples in coordinates between [-0.5..0.5] for height

 * and [-w/h/2..w/h/2] for width. It works in phases: initSampleSet returns

 * number of samples for each phase, then samples can be generated using

 * nextSample method. The resulting colour of each sample should be returned

 * via saveSample method. The sampler should save the results to given buffer

 * and decide if another phase is needed. When the picture is complete,

 * initSampleSet returns zero and picture can be read from buffer.

 */

class Sampler

{

protected:

	Pixmap pixmap;    ///< A pixmap for resulting image.

	bool packetable;  ///< True if the generated samples are usable with ray packets.

public:

	/** Constructor with user provided image buffer. */

	Sampler(Float *buffer, const int &w, const int &h):

		pixmap(buffer, w, h), packetable(false) {};

	/** With this constructor, image buffer is allocated as specified by w,h. */

	Sampler(const int &w, const int &h):

		pixmap(w, h), packetable(false) {};

	virtual ~Sampler() {};

	/** Switch to new user provided buffer. */

	void resetBuffer(Float *buffer, int &w, int &h)

		{ pixmap.setData(buffer, w, h); };

	/**

	 * Initialize the sampler.

	 *

	 * This must be called first when starting new image.

	 */

	virtual void init() = 0;

	/**

	 * Prepare for next phase.

	 *

	 * Must be called before reading samples.

	 * @retval N approximate number of samples to be generated in the phase

	 * @retval 0 last phase, image is complete

	 */

	virtual int initSampleSet() = 0;

	/**

	 * Generate next sample.

	 *

	 * @param[out] s  The sample.

	 * @retval false  No more samples in this phase.

	 */

	virtual bool nextSample(Sample *s) = 0;

	/**

	 * Save the color of the sample.

	 *

	 * @param[in] samp  A sample.

	 * @param[in] col   Color resulted from ray tracing the sample.

	 */

	virtual void saveSample(const Sample &samp, const Colour &col) = 0;

	/** True if generated samples are usable with ray packets. */

	bool packetableSamples() { return packetable; };

	/** Get the pixmap. */

	const Pixmap &getPixmap() const { return pixmap; };

};

/**

 * Default sampler.

 *

 * Implements basic adaptive subsampling and oversampling.

 */

class DefaultSampler: public Sampler

{

	int phase;      ///< Current phase

	int subsample;  ///< Subsampling mode

	int oversample; ///< Oversampling mode

	//@{

	/** Properties of last generated sample. */

	int sx,sy,osa_samp;

	//@}

public:

	/** Constructor with user provided image buffer. */

	DefaultSampler(Float *buffer, const int &w, const int &h):

		Sampler(buffer, w, h), phase(-1), subsample(0), oversample(0) {};

	/** With this constructor, image buffer is allocated as specified by w,h. */

	DefaultSampler(const int &w, const int &h):

		Sampler(w, h), phase(-1), subsample(0), oversample(0) {};

	/* Implement virtuals from Sampler. */

	void init();

	int initSampleSet();

	bool nextSample(Sample *s);

	void saveSample(const Sample &samp, const Colour &col);

	/**

	  * Set subsampling mode.

	  *

	  * @param[in] sub  0,1 = no, 1+ = size of sampling grid

	  */

	void setSubsample(int sub) { subsample = sub; };

	/** Get subsampling mode. @see setSubsample */

	int getSubsample() { return subsample; };

	/**

	  * Set oversampling mode.

	  *

	  * @param[in] osa  0 = no, 1 = 4x, 2 = 9x, 3 = 16x

	  */

	void setOversample(int osa) { oversample = osa; };

	/** Get oversampling mode. @see setOversample */

	int getOversample() { return oversample; };

};

#endif