2014/10/15 下午 10:04:50

iphone Programming Glossary: c1

Find the tangent of a point on a cubic bezier curve (on an iPhone)

http://stackoverflow.com/questions/4089443/find-the-tangent-of-a-point-on-a-cubic-bezier-curve-on-an-iphone

C first calcuate what are usually know as the coeffients they are trivial based on the four control points CGFloat C1 d 3.0 c 3.0 b a CGFloat C2 3.0 c 6.0 b 3.0 a CGFloat C3 3.0 b 3.0 a CGFloat C4 a not needed for this calculation finally.. not needed for this calculation finally it is easy to calculate the slope element using those coefficients return 3.0 C1 t t 2.0 C2 t C3 note that this routine works for both the x and y side simply run this routine twice once for x once for.. of course you could calculate the four 'coefficients' only once for both this and the slope calculation CGFloat C1 d 3.0 c 3.0 b a CGFloat C2 3.0 c 6.0 b 3.0 a CGFloat C3 3.0 b 3.0 a CGFloat C4 a it's now easy to calculate the point using..

How do I detect a touch on a UIBezierPath and move a ball along that?

http://stackoverflow.com/questions/4854035/how-do-i-detect-a-touch-on-a-uibezierpath-and-move-a-ball-along-that

tangents of those along a bezier cubic CGFloat bezierPoint CGFloat t CGFloat a CGFloat b CGFloat c CGFloat d CGFloat C1 d 3.0 c 3.0 b a CGFloat C2 3.0 c 6.0 b 3.0 a CGFloat C3 3.0 b 3.0 a CGFloat C4 a return C1 t t t C2 t t C3 t C4 CGFloat.. CGFloat c CGFloat d CGFloat C1 d 3.0 c 3.0 b a CGFloat C2 3.0 c 6.0 b 3.0 a CGFloat C3 3.0 b 3.0 a CGFloat C4 a return C1 t t t C2 t t C3 t C4 CGFloat bezierTangent CGFloat t CGFloat a CGFloat b CGFloat c CGFloat d CGFloat C1 d 3.0 c 3.0 b a.. C4 a return C1 t t t C2 t t C3 t C4 CGFloat bezierTangent CGFloat t CGFloat a CGFloat b CGFloat c CGFloat d CGFloat C1 d 3.0 c 3.0 b a CGFloat C2 3.0 c 6.0 b 3.0 a CGFloat C3 3.0 b 3.0 a CGFloat C4 a return 3.0 C1 t t 2.0 C2 t C3 The four..