java - Shooting Bullets with mouse, Math.atan2

Question

So i code a 2D Shooter were you use the mouse to shoot:

timeSinceLastShot+=timeSinceLastFrame;
        double bullet_angle = Math.atan2(MyMouseListener.getClickPosY()-posY, MyMouseListener.getClickPosX()-posX);
        float bullet_startX = posX+(skin.getWidth()/2)-(Bullet.getImg().getWidth()/2);
        float bullet_startY = posY+(skin.getHeight()/2)-(Bullet.getImg().getHeight()/2);
        double bullet_speedX = Math.cos(bullet_angle * Math.PI/180)*500;
        double bullet_speedY = Math.sin(bullet_angle * Math.PI/180)*500;

        if(timeSinceLastShot>(1f/shotsPerSec) && MyMouseListener.isButtonClicked(MouseEvent.BUTTON1)){
            bullets.add(new Bullet(bullet_startX, bullet_startY, bullet_speedX, bullet_speedY));
            timeSinceLastShot = 0;
        }

All Bullets go to the right, but i want them to go exactly in the direction of the mouse.

Answer 1

我认为您正在尝试将 bullet_angle 转换为弧度，但它已经是弧度。从本质上讲，bullet_speed 是在角度=0 的情况下计算的，即直角。从 cos() 和 sin() 计算中删除“* Math.PI/180”。

timeSinceLastShot+=timeSinceLastFrame;

double bullet_angle = Math.atan2(MyMouseListener.getClickPosY()-posY, MyMouseListener.getClickPosX()-posX);
float bullet_startX = posX+(skin.getWidth()/2)-(Bullet.getImg().getWidth()/2);
float bullet_startY = posY+(skin.getHeight()/2)-(Bullet.getImg().getHeight()/2);
double bullet_speedX = Math.cos(bullet_angle)*500;
double bullet_speedY = Math.sin(bullet_angle)*500;

if(timeSinceLastShot>(1f/shotsPerSec) && MyMouseListener.isButtonClicked(MouseEvent.BUTTON1)){
    bullets.add(new Bullet(bullet_startX, bullet_startY, bullet_speedX, bullet_speedY));
    timeSinceLastShot = 0;
}