separating-axis-theorem

Objective-C check if subviews of rotated UIViews intersect?

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I don't know where to start with this one. Obviously CGRectIntersectsRect will not work in this case, and you'll see why. I have a subclass of UIView that has a UIImageView inside it that is placed in the exact center of the UIView: I then rotate the custom UIView to maintain the frame of the inner UIImageView while still being able to perform a CGAffineRotation. The resulting frame looks something like this: I need to prevent users from making these UIImageViews intersect, but I have no idea how to check intersection between the two UIImageViews, since not only do their frames not apply to

Determine if crop rect is entirely contained within rotated UIView

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问题 Premise: I'm building a cropping tool that handles two-finger arbitrary rotation of an image as well as arbitrary cropping. Sometimes the image ends up rotated in a way that empty space is inserted to fill a gap between the rotated image and the crop rect (see the examples below). I need to ensure that the image view, when rotated, fits entirely into the cropping rectangle. If it doesn't, I then need to re-transform the image (zoom it) so that it fits into the crop bounds. Using this answer,

Objective-C check if subviews of rotated UIViews intersect?

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问题 I don't know where to start with this one. Obviously CGRectIntersectsRect will not work in this case, and you'll see why. I have a subclass of UIView that has a UIImageView inside it that is placed in the exact center of the UIView: I then rotate the custom UIView to maintain the frame of the inner UIImageView while still being able to perform a CGAffineRotation. The resulting frame looks something like this: I need to prevent users from making these UIImageViews intersect, but I have no idea

Algorithm to detect intersection of two rectangles?

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问题 I\'m looking for an algorithm to detect if two rectangles intersect (one at an arbitrary angle, the other with only vertical/horizontal lines). Testing if a corner of one is in the other ALMOST works. It fails if the rectangles form a cross-like shape. It seems like a good idea to avoid using slopes of the lines, which would require special cases for vertical lines. 回答1: The standard method would be to do the separating axis test (do a google search on that). In short: Two objects don't