Question

I have started to learn game physics and I am trying to move a ball with an angle. But it does not change its angle. Java coordinate system is a little different and I think my problem is there. Here is my code.

This is for calculating x and y speed:

 scale_X= Math.sin(angle);
 scale_Y=Math.cos(angle);
     velosity_X=(speed*scale_X);
 velosity_Y=(speed*scale_Y);

This is for moving ball in run() function:

  ball.posX =ball.posX+(int)velosity_X;
  ball.posY=ball.posY+(int)velosity_Y;

I used (int)velosity_X and (int)velosity_Y because in ball class I draw object

g.drawOval(posX, posX, width, height);

and here g.drawOval requires int. I dont know if it is a problem or not. Also if I use angle 30 it goes +X and +Y but if I use angle 35 it goes -X and -Y. I did not figure out how to work coordinate system in Java.

Answer 1

Math.sin() and Math.cos() expect the angle in radians. You should transform your angles to radians (angle*Math.PI/180).