/*
   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/camera.h"
#include "render/dust.h"
#include "render/gl.h"
#include "core/application.h"
#include "core/gameinterface.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;

float *dust = 0;
size_t dustsize = 0;

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", "1024", 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) {
		free(dust);
		dust = 0;
		dustsize = 0;
	}
}

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

void Dust::draw(const Camera &camera, const math::Color &dustcolor)
{
	float alpha = 0.0f;
	float traillength = 0.0f;

	if (!r_dust->value()) {
		if (dust) {
			free(dust);
			dust = 0;
		}
		dustsize = 0;
		return;
	}

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

	if (dustsize <= 0) {
		if (dust) {
			free(dust);
			dust = 0;
		}
		dustsize = 0;
		return;
	}

	if (!core::localcontrol()) {
		return;
	}

	const float dust_distance = camera.distance() * camera.multiplier();

	if (!dust) {
		con_debug << "  generating dust..." << std::endl;

		dust = (float *) malloc(sizeof(float) * dustsize * 3);

		for (size_t i = 0; i < dustsize; i++) {
			dust[i*3] = core::localcontrol()->location().x() + (math::randomf(2) - 1) * (dust_distance + core::localcontrol()->radius() * 2.0f);
			dust[i*3+1] = core::localcontrol()->location().y() + (math::randomf(2) - 1) * (dust_distance + core::localcontrol()->radius() * 2.0f);
			dust[i*3+2] = core::localcontrol()->location().z() + (math::randomf(2) - 1) * (dust_distance + core::localcontrol()->radius() * 2.0f);
		}
	}


	traillength = math::max(core::localcontrol()->speed() * 0.5f, 0.5f);
	traillength = traillength * TRAILLENGHT / LOWSPEEDLIMIT;

	math::Color color(dustcolor);
	alpha = math::min(core::localcontrol()->speed(), 1.0f);
	color.a = 0.25f * alpha;

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

	for (size_t i = 0; i < dustsize; i++) {
		float dsquare = 0;
		for (size_t j = 0; j < 3; j++) {
			dsquare += (core::localcontrol()->location()[j] - dust[i*3+j]) * (core::localcontrol()->location()[j] - dust[i*3+j]);
			v[j] = dust[i*3+j] - core::localcontrol()->axis().forward()[j] * traillength;
		}

		if (dsquare > (2.0f * core::localcontrol()->radius() + dust_distance)*(2.0f * core::localcontrol()->radius() + dust_distance)) {
			for (size_t j = 0; j < 3; j++) {
				dust[i*3+j] = core::localcontrol()->location()[j] + (math::randomf(2) - 1) * (dust_distance + core::localcontrol()->radius() * 2.0f);
				v[j] = dust[i*3+j] - core::localcontrol()->axis().forward()[j] * traillength;
			}
		}

		gl::vertex(&dust[i*3]);
		gl::vertex(v);
	}

	gl::end();
}

}