• Adobe After Effects Expressions

  Asteroids-like “Screen Wrap” effect?

  Posted by Phil Aupperle on April 18, 2016 at 10:35 pm

  I have the “throw” expression on the x position parameter of a layer, and I’m trying to modify it to return to 0 after it goes past a certain point, like the asteroids in Asteroids. AE is fine with this code, but the layer just keeps going off to the right, never to be seen again. What am I missing? Is the value of x not being updated with the current position on every frame, is it not getting reset to 0, or is there a problem with using only one of the values from position?

  Thanks in advance…

  veloc = 300; //horizontal velocity (pixels per second)
x = position[0];
if (x > 500) {
x = 0;
} else {
x = position[0] + (time - inPoint) *veloc;
}
x

  Kalleheikki Kannisto replied 10 years, 3 months ago 2 Members · 1 Reply
• 1 Reply

• 

  Kalleheikki Kannisto

  April 19, 2016 at 2:26 pm

  If you separate dimensions, you can use “x” value only.

  This would be one way to do what you are describing (use for x-position after separating dimensions):

  veloc = 300; //horizontal velocity (pixels per second)
x = (value+ (time - inPoint) *veloc) % 500

  It works in the positive direction only.

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