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In my 2d java game, I need to move projectiles from Enemy object to Player object in a straight line. I did some research and found out that I can use atan2(x, y) method of Math class to get the angle, but then how am i supposed to move the projectile in that particular angle(direction)? Any ideas would be very helpful.

anonymous
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    If you're attempting any kind of spatial game programming, it will be a painful experience unless you've learnt some basic geometry and trigonometry first. I suggest you pick up a decent maths textbook before going too much further. – Oliver Charlesworth Sep 26 '14 at 10:19
  • Check http://stackoverflow.com/questions/21483999/using-atan2-to-find-angle-between-two-vectors or http://stackoverflow.com/questions/6222671/angle-from-vector – Tom Sep 26 '14 at 10:21

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The equation of movment with constant speed is simple

positionX = startPositionX + speedX * time 
positionY = startPositionX + speedY * time

where

speedX = speed * sin(angle)
speedY = speed * cos(angle)

But most of the game use incremental aproach

posX = posX + speedX / lengthOfTick
posY = posY + speedY / lengthOfTick
talex
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