/*  Starshatter: The Open Source Project
    Copyright (c) 2021-2024, Starshatter: The Open Source Project Contributors
    Copyright (c) 2011-2012, Starshatter OpenSource Distribution Contributors
    Copyright (c) 1997-2006, Destroyer Studios LLC.

    AUTHOR:       John DiCamillo


    OVERVIEW
    ========
    Particle Burst class
*/

#include "Particles.h"
#include "Projector.h"
#include "Light.h"
#include "Bitmap.h"
#include "Clock.h"
#include "Random.h"

// +--------------------------------------------------------------------+

inline float randf() { return (rand()-16384.0f)/32768.0f; }

// +--------------------------------------------------------------------+

Particles::Particles(Bitmap* bitmap, int np, const Vec3& base_loc, const Vec3& vel,
float bspeed, float dr, float s, float bloom, float dec, float rate,
bool cont, bool trail, bool rise, int a, int nframes)
: nparts(np), base_speed(bspeed), max_speed(bspeed*3.0f),
drag(dr), min_scale(s), max_scale(bloom), decay(dec),
release_rate(rate), continuous(cont), trailing(trail), rising(rise),
blend(a), extra(0.0f), point_sprite(0), emitting(true)
{
    MoveTo(base_loc);
    ref_loc     = base_loc;

    trans       = true;
    luminous    = true;
    shadow      = false;
    nverts      = nparts;

    if (max_scale < min_scale)
    max_scale = min_scale;

    velocity    = new Point[nverts];
    part_loc    = new Point[nverts];
    release     = new Point[nverts];
    intensity   = new float[nverts];
    timestamp   = new float[nverts];
    scale       = new float[nverts];
    angle       = new float[nverts];
    frame       = new BYTE[nverts];

    float speed = base_speed;

    for (int i = 0; i < nverts; i++) {
        intensity[i]   = 1.0f;
        timestamp[i]   = (float) (Clock::GetInstance()->GameTime() / 1000.0);
        scale[i]       = (float) (min_scale);
        angle[i]       = (float) (Random(0, 2*PI));
        frame[i]       = 0;

        part_loc[i]    = Point();
        release[i]     = ref_loc;
        velocity[i]    = RandomVector(speed);
        velocity[i] += vel;

        if (speed < max_speed)
        speed += (float) Random(max_speed/15.0, max_speed/5.0);
        else
        speed = base_speed;
    }

    radius = 15000.0f;

    if (decay > 2)
    decay /= 256.0f;

    if (nparts < 8) {
        nverts = 1;
    }

    else if (nparts > 50 || continuous) {
        nverts = (int) (nparts * 0.125 * release_rate);
    }

    point_sprite = new Sprite(bitmap, nframes);
    point_sprite->Scale(s);
    point_sprite->SetBlendMode(blend);
    point_sprite->SetFrameRate(nframes * decay);
}

Particles::~Particles()
{
    delete    point_sprite;
    delete [] velocity;
    delete [] part_loc;
    delete [] release;
    delete [] timestamp;
    delete [] intensity;
    delete [] scale;
    delete [] angle;
    delete [] frame;
}

// +--------------------------------------------------------------------+

void Particles::ExecFrame(double seconds)
{
    point_sprite->Update();

    ref_loc = loc;
    radius += max_speed * (float) seconds;

    float scaled_drag = (float) exp(-drag * seconds);
    float scale_inc   = (float) ((max_scale-min_scale)*seconds*2);

    for (int i = 0; i < nverts; i++) {
        part_loc[i] += velocity[i] * (float) seconds;

        if (rising) {
            part_loc[i].y += (float) ((randf() + 1) * scale[i] * 80 * seconds);
        }

        // do the (chunky) blooming effect:
        if (max_scale > 0 && scale[i] < max_scale) {
            scale[i] += scale_inc * (float) ((i%3)/3.0);
        }

        double      rho = angle[i];
        int         rot = i%4;
        switch (rot) {
        case 0:     rho += seconds * 0.13;  break;
        case 1:     rho -= seconds * 0.11;  break;
        case 2:     rho += seconds * 0.09;  break;
        case 3:     rho -= seconds * 0.07;  break;
        default:                            break;
        }

        angle[i]      = (float) rho;
        intensity[i] -= (float) (decay * seconds);

        if (point_sprite->NumFrames() > 1) {
            double age = Clock::GetInstance()->GameTime()/1000.0 - timestamp[i];
            int    n   = (int) (age * point_sprite->FrameRate());

            if (n >= point_sprite->NumFrames())
            n = point_sprite->NumFrames() - 1;

            frame[i] = n;
        }

        velocity[i] *= scaled_drag;
    }

    if (nverts < nparts && emitting) {
        int    nv        = nverts;
        double delta     = nparts * release_rate * seconds;
        int    new_parts = (int)   (delta + extra);
        extra     = (float) (delta + extra - new_parts);
        nverts   += new_parts;

        if (nverts > nparts)
        nverts = nparts;

        for (int i = nv; i < nverts; i++) {
            intensity[i]   = 1;
            timestamp[i]   = (float) (Clock::GetInstance()->GameTime() / 1000.0);
            scale[i]       = (float) (min_scale);
            angle[i]       = (float) (Random(0, 2*PI));
            frame[i]       = 0;
            part_loc[i]    = Point();
            release[i]     = ref_loc;
        }
    }

    if (nverts > nparts)
    nverts = nparts;

    // recycle dead particles:
    if (continuous) {
        float speed = base_speed;

        for (int i = 0; i < nverts; i++) {
            if (intensity[i] <= 0) {
                part_loc[i]    = Point();
                release[i]     = ref_loc;

                intensity[i]   = 1;
                timestamp[i]   = (float) (Clock::GetInstance()->GameTime() / 1000.0);
                scale[i]       = (float) (min_scale);
                angle[i]       = (float) (PI * rand() / 16384.0);
                frame[i]       = 0;
                velocity[i]    = RandomVector(speed);

                if (speed < max_speed)
                speed += (float) Random(max_speed/25.0, max_speed/18.0);
                else
                speed = base_speed;
            }
        }
    }
}

// +--------------------------------------------------------------------+

bool
Particles::CheckVisibility(Projector& projector)
{
    float base = 256;

    if (point_sprite && point_sprite->Frame())
    base = (float) point_sprite->Frame()->Width();

    float particle_radius = base * max_scale;

    if (projector.IsVisible(     Location(), Radius()) &&
            projector.ApparentRadius(Location(), particle_radius) > 1) {

        visible = true;
    }
    else {
        visible = false;
    }

    return visible;
}

// +--------------------------------------------------------------------+

void
Particles::Render(Video* video, DWORD flags)
{
    if (hidden || !visible || !video || !point_sprite)
    return;

    if (blend == 2 && !(flags & Graphic::RENDER_ALPHA))
    return;

    if (blend == 4 && !(flags & Graphic::RENDER_ADDITIVE))
    return;

    for (int i = 0; i < nverts; i++) {
        Point vloc;

        if (trailing) {
            vloc = part_loc[i] + release[i] - offset;
        }
        else {
            vloc = part_loc[i] + loc;
        }

        point_sprite->MoveTo(vloc);
        point_sprite->SetShade(intensity[i]);
        point_sprite->Rescale(scale[i]);
        point_sprite->SetAngle(angle[i]);
        point_sprite->SetFrameIndex(frame[i]);

        point_sprite->Render(video, flags);
    }
}