/*
   render/dust.cc
   This file is part of the Osirion project and is distributed under
   the terms of the GNU General Public License version 2
*/

#include "render/dust.h"
#include "render/gl.h"
#include "core/cvar.h"
#include "core/core.h"
#include "math/functions.h"
#include "sys/sys.h"

namespace render
{

core::Cvar *r_dust;
core::Cvar *r_dustsize;

const float LOWSPEEDLIMIT = 5.0f;
const float TRAILLENGHT = 0.25f;
const float DUSTMAXALPHA = 0.8f;
const float DUSTDISTANCE = 8.0f;

float	*dust;
size_t dustsize;

void Dust::init()
{
	r_dust = core::Cvar::get("r_dust", "1", core::Cvar::Archive);
	r_dust->set_info("[bool] render dust");

	r_dustsize = core::Cvar::get("r_dustsize", "128", core::Cvar::Archive);
	r_dustsize->set_info("[int] number of dust particles");

	dust = 0;
	dustsize = (size_t) r_dustsize->value();
}

void Dust::shutdown()
{
	if (dust) {
		delete dust;
		dust = 0;
		dustsize = 0;
	}
}

void Dust::reset()
{
	delete dust;
	dust = 0;
}

void Dust::draw()
{
	if (!r_dust->value()) {
		if (dust) {
			delete dust;
			dust = 0;
		}
		return;
	}
	
	if (!core::localcontrol()) {
		return;
	}

	if ((size_t) r_dustsize->value() != dustsize) {
		con_debug << "  changing dust size..." << std::endl;
		if (dust) {
			delete dust;
			dust = 0;
		}
	}

	dustsize = (size_t) r_dustsize->value();

	if (!dustsize)	{
		if (dust) {
			delete dust;
			dust = 0;
		}
		return;
	}

	if (!dust) {
		con_debug << "  generating dust..." << std::endl;
		dust = new float[dustsize*3];

		for (size_t i = 0; i < dustsize; i++) {
			dust[i*3] = core::localcontrol()->location().x +  (math::randomf(2) - 1) * (DUSTDISTANCE + core::localcontrol()->radius());
			dust[i*3+1] = core::localcontrol()->location().y + (math::randomf(2) - 1) * (DUSTDISTANCE + core::localcontrol()->radius());
			dust[i*3+2] = core::localcontrol()->location().z + (math::randomf(2) - 1) * (DUSTDISTANCE + core::localcontrol()->radius());
		}
	}

	if (!core::localcontrol()->speed()) 
		return;

	math::Color color;
	if (core::localcontrol()->speed() < LOWSPEEDLIMIT) {
		color.a = core::localcontrol()->speed() / LOWSPEEDLIMIT;
	}
	color.a	*= DUSTMAXALPHA;

	gl::color(color);
	gl::begin(gl::Lines);
	math::Vector3f v;

	for (size_t i = 0; i < dustsize; i++) {
		v.assign(core::localcontrol()->location());
		for (size_t j = 0; j < 3; j++)
			v[j] -=  dust[i*3+j];

		if (v.lengthsquared() > (core::localcontrol()->radius() + DUSTDISTANCE)*(core::localcontrol()->radius() + DUSTDISTANCE)) {

			dust[i*3] = core::localcontrol()->location().x +  (math::randomf(2) - 1) * (DUSTDISTANCE + core::localcontrol()->radius());
			dust[i*3+1] = core::localcontrol()->location().y + (math::randomf(2) - 1) * (DUSTDISTANCE + core::localcontrol()->radius());
			dust[i*3+2] = core::localcontrol()->location().z + (math::randomf(2) - 1) * (DUSTDISTANCE + core::localcontrol()->radius());
		}

		glVertex3fv(dust+3*i);

		for (size_t j = 0; j < 3; j++)
			v[j] = dust[i*3+j];
		v -= core::localcontrol()->state()->axis().forward() * color.a * TRAILLENGHT;
		gl::vertex(v);
	}

	gl::end();
}

}