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Collision Detection
Posted on 2004-04-21
Hello all, thanks for helping!
I'm currently programming a spaceship game, where 2 ships duke it out.
Each ship is an image, and the lasers that fly between them are fillRects.
Ok, ok, now to the problem. Both of my ships rotate a full 360 degrees, and are very rectangular in shape. This creates a huge problem for me when if comes to collision detection, or when the lasers hit the ship.
Is there any easier way to detect if a point is in a given region (even a circular region for that matter) with out having to make an impossibly long if statement?
I'm really looking for an easy way to see if a point has entered the area in which my image or other thing takes up.
Thanks!
I'm currently programming a spaceship game, where 2 ships duke it out.
Each ship is an image, and the lasers that fly between them are fillRects.
Ok, ok, now to the problem. Both of my ships rotate a full 360 degrees, and are very rectangular in shape. This creates a huge problem for me when if comes to collision detection, or when the lasers hit the ship.
Is there any easier way to detect if a point is in a given region (even a circular region for that matter) with out having to make an impossibly long if statement?
I'm really looking for an easy way to see if a point has entered the area in which my image or other thing takes up.
Thanks!
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7 Comments
Well to see if a point (x1,y1) falls within a circle of radius r, centered at (x2,y2), just check if (x2-x1)^2 + (y2-y1)^2 <= r^2.
Do you need a formula for finding whether a point is within a rotated rectangle? Or are you looking for something much more automatic, like a method on an object that just figures it out for that object?
Do you need a formula for finding whether a point is within a rotated rectangle? Or are you looking for something much more automatic, like a method on an object that just figures it out for that object?
check out the contains() methods on these classes:
java.awt.Rectangle: http://java.sun.com/j2se/1.4.2/docs/api/java/awt/Rectangle.html
java.awt.Polygon: http://java.sun.com/j2se/1.4.2/docs/api/java/awt/Polygon.html
java.awt.geom.Area: http://java.sun.com/j2se/1.4.2/docs/api/java/awt/geom/Area.html
java.awt.Rectangle: http://java.sun.com/j2se/1.4.2/docs/api/java/awt/Rectangle.html
java.awt.Polygon: http://java.sun.com/j2se/1.4.2/docs/api/java/awt/Polygon.html
java.awt.geom.Area: http://java.sun.com/j2se/1.4.2/docs/api/java/awt/geom/Area.html
@seanrowen Either is good, although I'm looking for the REAL easy way out. : )
@manifoldronin This is the stuff I'm looking for a little more. But how exactly would I use this, with say, an image? Especially one that is constantly changing by rotation?
@manifoldronin This is the stuff I'm looking for a little more. But how exactly would I use this, with say, an image? Especially one that is constantly changing by rotation?
Each image has a bound rectangle, right? And even though the image rotates constantly, at any given time (say the point you are drawing one frame). So you basically have the abstraction of a rectangle(var ship). Assuming one laser beam is a rectangle(var laser) as well, essentially you just need to test these conditions:
1. ship.contains(laser.x);
2. ship.contains(laser.y);
3. ship.contains(laser.x+lase
4. ship.contains(laser.y+lase
5. ship.contains(laser);
Any of those is true, you have a collision.
1. ship.contains(laser.x);
2. ship.contains(laser.y);
3. ship.contains(laser.x+lase
4. ship.contains(laser.y+lase
5. ship.contains(laser);
Any of those is true, you have a collision.
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