Shoot

You want the player to shoot when a key is pressed. The shot is another object, created on the spot by the code.

Create an object Bullet with the sprite of the shot and this code:

#include <brasa/brasa.hpp>
using namespace brasa;

class Bullet : public Entity {
public:
    void onSpawn() override { vspeed = -5.0f; }   // goes up 5 pixels per step
    void onUpdate() override {
        if (y < -8.0f) destroy();                   // left the screen: disappear
    }
};
BRASA_ENTITY(Bullet);

And in the object that shoots:

void onUpdate() override {
    if (pressed(Key::Space)) spawn<Bullet>(x, y, "Instancias");
}

How it works

• spawn<Bullet>(x, y, "Instancias") creates a new instance of Bullet at the given position. Here, at the position of whoever shot. The third value is the layer the shot goes into: Instancias is the one every new room already has.
• In the shot’s onSpawn, vspeed = -5 makes it go up by itself: Brasa adds hspeed/vspeed to the position on every step.
• A shot that leaves the screen is destroyed, so invisible objects don’t pile up.

Note

One object uses another (the player uses Bullet) with no #include: in Brasa, every object sees all the others. See 3. Shots.

Variations

Hold to shoot in bursts, with a pause between the shots:

// in the class: bool canShoot_ = true;
if (held(Key::Space) && canShoot_) {
    spawn<Bullet>(x, y, "Instancias");
    canShoot_ = false;
    after(10, [this] { canShoot_ = true; });  // again 10 steps from now
}

Shoot in any direction. spawn returns the shot it created, so you can change its speed. Vec2::fromAngle(strength, degrees) turns an angle into a speed (0 = right, 90 = up):

if (Bullet* bullet = spawn<Bullet>(x, y, "Instancias")) {
    const Vec2 v = Vec2::fromAngle(5.0f, angleTo(mouseX(), mouseY()));  // towards the mouse
    bullet->hspeed = v.x;
    bullet->vspeed = v.y;
}

The shot’s onSpawn runs inside spawn, so the speed you set afterwards is the one that counts.

See also

• Instances and Timers.
• 3. Shots, in the tutorial.