/*
 * Copyright 2012-2013 Tri-Edge AI <triedgeai@gmail.com>
 * Copyright 2014 Haiku, Inc. All rights reserved.
 *
 * Distributed under the terms of the MIT license.
 *
 * Authors:
 *              Tri-Edge AI
 *              John Scipione, jscipione@gmail.com
 */


#include "Particle.h"

#include <stdlib.h>


#define frand() ((float)rand() / (float)RAND_MAX)


BObjectList<Particle>* Particle::list;


/*static*/ void
Particle::Initialize(int32 size, int32 shade)
{
        list = new BObjectList<Particle>(2048);

        for (int32 i = 0; i < size; i++) {
                Particle* p = new Particle();
                Particle::_FillParticle(p, size, shade);
                list->AddItem(p);
        }
}


/*static*/ void
Particle::AddParticles(int32 size, int32 shade)
{
        for (int32 i = list->CountItems(); i < size; i++) {
                Particle* p = new Particle();
                Particle::_FillParticle(p, size, shade);
                list->AddItem(p);
        }
}


/*static*/ void
Particle::RemoveParticles(int32 size, int32 shade)
{
        while (list->CountItems() > size)
                delete list->RemoveItemAt(list->CountItems() - 1);
}


/*static*/ void
Particle::ColorParticles(int32 size, int32 shade)
{
        for (int32 i = 0; i < size; i++) {
                Particle* p = list->ItemAt(i);
                Particle::_ColorParticle(p, size, shade);
        }
}


/*static*/ void
Particle::Terminate()
{
        list->MakeEmpty();
        delete list;
}


/*static*/ void
Particle::Tick()
{
        for (int32 i = 0; i < list->CountItems(); i++) {
                Particle* p = list->ItemAt(i);
                p->_Logic();
                p->_Render();
        }
}


void
Particle::_Logic()
{
        // Motion
        x += vx;
        y += vy;
        z += vz;
        r += vr;

        // Friction
        vx *= 0.98f;
        vy *= 0.98f;
        vz *= 0.98f;
        vr *= 0.98f;
}


void
Particle::_Render() const
{
        glPushMatrix();
        glTranslatef(x, y, z);
        glRotatef(r, 0.0f, 0.0f, 1.0f);
        glColor3f(red, green, blue);
        glBegin(GL_QUADS);
        glVertex3f(-0.25f,  0.25f,  0.0f);
        glVertex3f(-0.25f, -0.25f,  0.0f);
        glVertex3f( 0.25f, -0.25f,  0.0f);
        glVertex3f( 0.25f,  0.25f,  0.0f);
        glEnd();
        glPopMatrix();
}


/*static*/ void
Particle::_FillParticle(Particle* p, int32 size, int32 shade)
{
        p->x = frand() * 30.0f - 15.0f;
        p->y = frand() * 30.0f - 15.0f;
        p->z = frand() * 5.0f;
        p->r = frand() * 360.0f;

        p->vx = frand() - 0.5f;
        p->vy = frand() - 0.5f;
        p->vz = frand() - 0.5f;
        p->vr = (frand() - 0.5f) * 180.0f;

        Particle::_ColorParticle(p, size, shade);
}


/*static*/ void
Particle::_ColorParticle(Particle* p, int32 size, int32 shade)
{
        switch(shade) {
                case 0:
                        // Red
                        p->red   = 0.1f + frand() * 0.2f;
                        p->green = 0.0f;
                        p->blue  = frand() * 0.05f;
                        break;

                case 1:
                        // Green
                        p->red   = 0;
                        p->green = 0.1f + frand() * 0.2f;
                        p->blue  = frand() * 0.05f;
                        break;

                case 2:
                default:
                        // Blue
                        p->red   = 0;
                        p->green = frand() * 0.05f;
                        p->blue  = 0.1f + frand() * 0.2f;
                        break;

                case 3:
                        // Orange
                        p->red   = 0.1f + frand() * 0.1f;
                        p->green = 0.05f + frand() * 0.1f;
                        p->blue  = 0.0f;
                        break;

                case 4:
                        // Purple
                        p->red   = 0.1f + frand() * 0.2f;
                        p->green = 0.0f;
                        p->blue  = 0.1f + frand() * 0.2f;
                        break;

                case 5:
                        // White
                        p->red = p->green = p->blue = 0.1f + frand() * 0.2f;
                        break;

                case 6:
                        // Rainbow
                        p->red   = 0.1f + frand() * 0.2f;
                        p->green = 0.1f + frand() * 0.2f;
                        p->blue  = 0.1f + frand() * 0.2f;
                        break;
        }
}