flying-balls/spaceship.cc

#include "balls.h"
#include "game.h"

#include <gtk/gtk.h>
#include <math.h>

struct ball spaceship;
double spaceship_thrust = 0;
int spaceship_thrust_countdown = 0;
int spaceship_thrust_init = 50;

void spaceship_init_state() {
    spaceship.position.x = width / 2;
    spaceship.position.y = height / 2;
    spaceship.radius = 30;
    spaceship.velocity.x = 0;
    spaceship.velocity.y = 0;
    spaceship.angle = 0;
    spaceship.v_angle = 0;
}

void spaceship_update_state() {
    if (spaceship_thrust > 0) {
        vec2d f{cos(spaceship.angle) * spaceship_thrust * 4.0,
            sin(spaceship.angle) * spaceship_thrust * 4.0};

        spaceship.position += delta * delta * f / 2.0;
        spaceship.velocity += delta * f;
        if (spaceship_thrust_countdown > 0)
            --spaceship_thrust_countdown;
        else
            spaceship_thrust = 0;
    }
    ball_update_state(&spaceship);
}

void spaceship_draw(cairo_t* cr) {
    static const double one_over_sqrt_2 = 0.70710678118654752440;
    cairo_save(cr);
    cairo_set_source_rgba(cr, 0.0, 0.0, 1.0, 1.0);
    cairo_translate(cr, spaceship.position.x, spaceship.position.y);
    cairo_rotate(cr, spaceship.angle);
    cairo_arc(cr, 0, 0, spaceship.radius, 0, 2 * M_PI);
    cairo_stroke(cr);
    cairo_set_source_rgba(cr, 0.0, 1.0, 0.0, 1.0);
    cairo_move_to(cr, 0, 0);
    cairo_line_to(cr,
        -one_over_sqrt_2 * spaceship.radius,
        one_over_sqrt_2 * spaceship.radius);
    cairo_line_to(cr, spaceship.radius, 0);
    cairo_line_to(cr,
        -one_over_sqrt_2 * spaceship.radius,
        -one_over_sqrt_2 * spaceship.radius);
    cairo_line_to(cr, 0, 0);
    cairo_stroke(cr);
    cairo_set_source_rgba(cr, 1.0, 0.5, 0.0, 1.0);
    for (unsigned int i = 0; i < spaceship_thrust; i += 5) {
        double d_angle = spaceship.radius / (spaceship.radius + 0.1 * i) *
                         0.25 * M_PI * (1 - 0.99 * i / spaceship_thrust);
        cairo_set_source_rgba(
            cr, 1.0, 1.0 * (1 - 0.5 * i / spaceship_thrust), 0.0, 1.0);
        cairo_arc(
            cr, 0, 0, spaceship.radius + i, M_PI - d_angle, M_PI + d_angle);
        cairo_stroke(cr);
        if (d_angle > 0.05)
            d_angle = 0.7 * d_angle;
    }
    cairo_restore(cr);
}

void spaceship_control(double dx, double dy) {
    spaceship.angle -= dx / 4;
    if (spaceship.angle < 0)
        spaceship.angle += 2 * M_PI;
    else if (spaceship.angle > 2 * M_PI)
        spaceship.angle -= 2 * M_PI;
    spaceship_thrust += dy;
    if (spaceship_thrust > 0)
        spaceship_thrust_countdown = spaceship_thrust_init;
    else
        spaceship_thrust = 0;
}