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The CGRect functions accept start x and y and then width and height. But I have a rectangle that has been rotated. I want to use the CGRect functions to detect collisions. I know what each corner point is.
Or better yet, is there a way to detect if a regular rectangle intersects with another rectangle (or possibly a line) that has been rotated?
I've lost so much time trying to get angular collision detections working properly (without Chipmunk).
Steve Oldmeadow
Administrator
Here's a clue. If you want to test one point inside a rectangle instead of rotating the rectangle rotate the point so that it is in the local space of the rectangle when the rectangle is aligned with the axes. It is just maths, draw it up on a piece of paper.
You should be able to use the stuff in CGAffineTransform to do what you want.
http://developer.apple.com/documentation/GraphicsImaging/Reference/CGAffineTransform/Reference/reference.html#//apple_ref/c/func/CGAffineTransformMakeRotation
Justin
Osiris - "so no [rect setRotate:30.0f]; ??? "
I was hoping it would be that simple
Shivaz, would the CGAffineTransform allow me to rotate a CGRect, from what i can tell from the documentation. It would allow me to rotate the positions of my verts that define my shape, but that would only help if could create a CGRect from four points like JD was asking, but from what people said this doesn't seem possible?
Dave
I have been looking into the CGAffineTransform stuff some more, i found CGRectApplyAffineTransform, I think this is what I'm looking for but i cant quite get it work right.
Here is how i think i should be applying the AffineTransform -
CGRect myRect;
CGAffineTransform rotateME;
myRect = CGRectMake(x,y,w,h);
myRect.origin = ccp(x,y);
rotateME = CGAffineTransformMakeRotation(CC_DEGREES_TO_RADIANS(45));
//rotateME = CGAffineTransformMakeTranslation(0, 30);
myRect2 = CGRectApplyAffineTransform(myRect, rotateME);
This is moving the the rectangle, but not in anyway that makes sense. Am i setting the origin in the right place? Am i even on the right track for rotating a CGRect?
The line I have commented out works fine and moves the rectangle up 30 pixels.
This is one of the last major things I've got to get working. I'm really new to this, and learning as much as i can via the forums and hours of Google searches, but this one has got me really stuck...
Thanks for your help.
Dave
Seriously man, open Xcode's documentation, search for "CGRectApplyAffineTransform" and read what that function really does.
You have to understand that a CGRect is not a geometric rectangle. Once again, search for "CGRect" in Xcode's documentation and see by yourself.
I actually scrapped this method after spending far to long trying to get it to work, and went with a more probably a dirt method using chipmunks collision detection.
By moving a small physics block to the point of the touch, checking for a collision and then moving it back off screen. It seems to work and allows me to use any shape i can make out of polys which is nice.
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