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## Creating an invisible circle for collision

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### #1VisualChaser  Members

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Posted 15 June 2012 - 01:27 AM

As my first project I'm working on a tower defence game. The project is somewhere near 60% finished, including particles and all.
But I got stuck at coding the enemies and towers. I need an invisible circle that can be used to detect collision. If the enemy is in this circle (the circle is the range of the tower), the tower should start shooting. I also should be able to adjust the circle to the range of every tower, which can be upgraded. I already searched on some sites but I can't find a way to do this.
Can someone give me an example on how to do this?

### #2Ashaman73  Members

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Posted 15 June 2012 - 03:42 AM

Then just take the distance, or square distance, between enemy and tower to determine if it is inside the effect radius:
for each enemy do
delta.x = enemy.x - tower.x
delta.y = enemy.y - tower.y
// square distance = dotProduct(delta,delta)
square_distance = delta.x*delta.x+delta.y*delta.y
.. shoot at enemy
end
end


Edited by Ashaman73, 15 June 2012 - 03:42 AM.

Ashaman

### #3VisualChaser  Members

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Posted 15 June 2012 - 11:33 AM

Yes that should work. But in C++ the script would be even easier I think, I'll figure something out. Thanks!

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