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Socoder -> Cobra -> Circle / triangle maths |
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| Sat, 23 Jan 2010, 20:52 | |
HoboBen
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Given the co-ordinates of two points, and an angle, I'm trying to find the third. It's not working - can someone check my maths? Perhaps I'm wrong to assume a right-angle in step 2?   Here's my implementation... -=-=- blog | work | code | more code |
| Sat, 23 Jan 2010, 21:08 | |
Scherererer
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Why not use polar coordinates? assume the point A is the origin (so you may have to offset your values of x and y before and after the transformation). Going to polar:: r = sqrt(x^2+y^2) theta = arctan(y/x) ** you may have to use atan2 ** Coming back from polar:: x = r*cos(theta) y = r*sin(theta) so basically, convert it to polar, you'll get a value for r and theta for the point C with respect to the point A. Then add the angle A to theta, convert back to cartesian coordinates, and you've got the location for point B. again, if A isn't located at the origin, then you'll need to offset the values (just do C.x -= A.x, C.y -= A.y) and then unoffset them when you convert back to cartesian (B.x + A.x, B.y += A.y) -=-=- YouTube Twitter Computer Science Series: Logic (pt1) (part 2) (part 3) 2's Complement Mathematics: Basic Differential Calculus 
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| Sat, 23 Jan 2010, 22:35 | |
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HoboBen
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Thanks very much! I had to read up a lot on polar coordinates, but it seems to have done the trick! -=-=- blog | work | code | more code |
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