I have one coordinate and want to get a new coordinate after rotation like image below. Can anyone give me a simple formula ?
EDIT : after using eol formula...
there's a very small miss "6.1232338E-15".
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I'm afraid this is off-topic here. You can look this up in any math textbook. – Hulk Jul 03 '16 at 07:36
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if this so simple like that, can u post your math textbook formula here.. – Mardi Jul 03 '16 at 08:46
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2I'm voting to close this question as off-topic because it's a math problem. – Eiko Jul 03 '16 at 09:25
1 Answers
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Just use a rotation matrix (taken from https://en.wikipedia.org/wiki/Rotation_matrix):
float newX = x*Math.cos(angleRad) - y*Math.sin(angleRad);
float newY = x*Math.sin(angleRad) - y*Math.cos(angleRad);
One thing to mention is that you need to make sure that the angle is in radians, so you may need to perform this conversion:
float angleRad = angle*Math.PI/180;
eol
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I use your formula but there very small miss in calculation. i know it will ignore in render but you know why? – Mardi Jul 03 '16 at 09:45
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@Mardi This might be due to rounding errors. See http://stackoverflow.com/questions/1661273/floating-point-arithmetic-not-producing-exact-results – eol Jul 03 '16 at 10:31