//
// texture_cloud.cc
//
// Procedural cloud texture.
//
// Copyright (C) J. Belson	2003.09.27
//
// $Id: texture_cloud.cc,v 1.1 2003/10/11 18:11:00 jon Exp $
//


#include "texture_cloud.h"



/**
 * Load current settings.
 * @param	ts	textset_cloud instance to load into.
 */
void textset_cloud::load_settings(textset_cloud& ts)
{
	settings* my_settings = settings::get_instance();

	my_settings->get_colour(SKY_HORIZON_COLOUR, &ts.horizon_colour);
	my_settings->get_colour(SKY_ZENITH_COLOUR, &ts.zenith_colour);

	my_settings->get_int(CLOUD_SEED, &ts.seed);
	my_settings->get_colour(CLOUD_COLOUR, &ts.fg);
	my_settings->get_float(CLOUD_PERSISTENCE, &ts.persistence);
	my_settings->get_float(CLOUD_PRESENCE, &ts.presence);
	my_settings->get_float(CLOUD_COVER, &ts.cloud_cover);
	my_settings->get_float(CLOUD_SCALE, &ts.scale);
}


/**
 * Constructor.
 */
texture_cloud::texture_cloud(const textset_cloud& ts)
	: texture(ts)
{
	my_settings = settings::get_instance();

	scale			= ts.scale;
	presence		= ts.presence;
	cloud_cover		= ts.cloud_cover;

	horizon_colour	= ts.horizon_colour;
	zenith_colour	= ts.zenith_colour;

#ifdef USE_OLD_PERLIN
	noise = new perlin;
	noise->set_seed(ts.seed);
	noise->set_persistence(ts.persistence);
	noise->set_iterations(3);
#else
	noise = new perlin2;
	noise->set_seed(ts.seed);
	//noise->set_freq_scale(scale);
	scale *= 25;
#endif
}


/**
 * Destructor.
 */
texture_cloud::~texture_cloud()
{
	delete noise;
}


/**
 * Calculate colour at specified point.
 * @param	s	Texture coordinate.
 * @param	t	Texture coordinate.
 * @param	u	Texture coordinate.
 * @return		Colour at specified point.
 */
fcolour texture_cloud::colour(float s, float t, float /*u*/, vector3d*)
{
#ifdef USE_OLD_PERLIN
	// XXX original perlin routine cant handle -ve texture coordinates
	static const int TERRAIN_WIDTH = 256;
	float height = noise->perlin_noise_2d(scale*s + TERRAIN_WIDTH/2, scale*t +
				TERRAIN_WIDTH/2);
#else
	point2d pnt(scale*s, scale*t);
	float height = noise->noise2(pnt);
#endif

//	fcolour difference = zenith_colour - horizon_colour;
//	fcolour sky = zenith_colour + difference * (u - SKYDOME_OFFSET)/SKYDOME_SCALE;

	// Calculate clound density
	float val = cloud_cover + presence*height;
	if (val < 0) {
		val = 0;
	}
	float density = 1.0 - pow(0.5, val);

	fcolour colour = fg;	//*density;

	colour.alpha = density;

	return colour;
}