Updating position of an object with constant speed, regardless of direction

Question

I think this question is a little but stupid but I can't find the answer.

I'm doing the classic game pong. And I want that the ball goes at the same speed for any angle. But with my current algorithm (incrementing x by one and calculating y) if the a in y=ax+b is high there is big gaps between each pixel. What step should I use?

Answer 1

So we have something like this:

  newPoint
  |\
  | \
y |  \ r
  |  θ\
  |-----
     x  oldPoint

What you basically want is to make a step in distance related to r, not x.

From elementary trig:
cos θ = x/r
and sin θ = y/r

So newX = oldX + r * cos θ
and newY = oldY + r * sin θ

You can play around with r's value (this will basically be the speed of movement).

θ will be the direction of the ball.