blasteroids.c

#include "blasteroids.h"

int main(void) {
    ALLEGRO_DISPLAY *display;
    int display_width, display_height;
    Spaceship s;
    ALLEGRO_EVENT_QUEUE *q;
    ALLEGRO_TIMER *timer;
    ALLEGRO_EVENT event;

    al_init();
    al_init_primitives_addon();
    al_install_keyboard();
    display = al_create_display(800, 640);
    al_clear_to_color(al_map_rgba(0,0,0,255));
    al_flip_display();

    display_width = al_get_display_width(display);
    display_height = al_get_display_height(display);

    s.x = display_width/2;
    s.y = display_height/2;
    s.rotation = M_PI;

    s.rotating = 0;
    s.speed = 0;
    s.accelerating = 0;
    s.lifes = 3;
    s.color = al_map_rgb(255,255,255);

    q = al_create_event_queue();
    al_register_event_source(q, al_get_keyboard_event_source());
    timer = al_create_timer(1.0f/FPS);
    al_register_event_source(q, al_get_timer_event_source(timer));
    al_start_timer(timer);
    while (true) {
        al_wait_for_event(q, &event);
        if(event.type == ALLEGRO_EVENT_KEY_DOWN){
            switch (event.keyboard.keycode) {
                case ALLEGRO_KEY_LEFT:
                s.rotating = 1;
                break;
                case ALLEGRO_KEY_RIGHT:
                s.rotating = -1;
                break;
                case ALLEGRO_KEY_UP:
                s.accelerating = 1;
                break;
                case ALLEGRO_KEY_DOWN:
                s.accelerating = -1;
                break;
                case ALLEGRO_KEY_SPACE:
                //TODO
                break;
            }
        }else if(event.type == ALLEGRO_EVENT_KEY_UP){
            switch (event.keyboard.keycode) { //TODO: need to get adequate input. Considering using multiple threads
                case ALLEGRO_KEY_LEFT: //fall through
                case ALLEGRO_KEY_RIGHT:
                s.rotating = 0;
                break;
                case ALLEGRO_KEY_UP:  //fall through
                case ALLEGRO_KEY_DOWN:
                s.accelerating = 0;
                break;
                case ALLEGRO_KEY_SPACE:
                //TODO
                break;
            }
        }else if (event.type == ALLEGRO_EVENT_TIMER){
            //Redraw scene, ...
            al_clear_to_color(al_map_rgb(0,0,0));
            draw_spaceship(&s);
            al_flip_display();

            //... then compute physics
            //s.rotation += SPACESHIP_ANGULAR_VELOCITY*s.rotating/FPS;
            s.rotation = fmod(s.rotation + SPACESHIP_ANGULAR_VELOCITY*s.rotating/FPS, 2*M_PI);
            s.speed = clamp(s.speed + SPACESHIP_ACCELERATION*s.accelerating*(1.0f/FPS), SPACESHIP_MIN_SPEED, SPACESHIP_MAX_SPEED);

            s.x = clamp(s.x + s.speed*sin(s.rotation)*(1.0f/FPS), 0, (float)display_width);
            s.y = clamp(s.y + s.speed*cos(s.rotation)*(1.0f/FPS), 0, (float)display_height);
        }
    }
    return 0;
}

float clamp(float val, float min_val, float max_val){
    if(val > max_val) val = max_val;
    else if(val < min_val) val = min_val;
    return val;
}