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dupeguru/cocoalib/HSGeometry.m
2015-01-03 16:29:36 -05:00

71 lines
2.1 KiB
Objective-C

/*
Copyright 2015 Hardcoded Software (http://www.hardcoded.net)
This software is licensed under the "GPLv3" License as described in the "LICENSE" file,
which should be included with this package. The terms are also available at
http://www.gnu.org/licenses/gpl-3.0.html
*/
#import "HSGeometry.h"
CGFloat deg2rad(CGFloat deg)
{
return deg * M_PI / 180;
}
CGFloat distance(NSPoint p1, NSPoint p2)
{
CGFloat dX = p1.x - p2.x;
CGFloat dY = p1.y - p2.y;
return sqrt(dX * dX + dY * dY);
}
NSPoint pointInCircle(NSPoint center, CGFloat radius, CGFloat angle)
{
// a/sin(A) = b/sin(B) = c/sin(C) = 2R
// the start point it (center.x + radius, center.y) and goes counterclockwise
angle = fmod(angle, M_PI*2);
CGFloat C = M_PI/2;
CGFloat A = fmod(angle, M_PI/2);
CGFloat B = C - A;
CGFloat c = radius;
CGFloat ratio = c / sin(C);
CGFloat b = ratio * sin(B);
CGFloat a = ratio * sin(A);
if (angle >= M_PI * 1.5)
return NSMakePoint(center.x + a, center.y - b);
else if (angle >= M_PI)
return NSMakePoint(center.x - b, center.y - a);
else if (angle >= M_PI/2)
return NSMakePoint(center.x - a, center.y + b);
else
return NSMakePoint(center.x + b, center.y + a);
}
CGFloat angleFromPoints(NSPoint pt1, NSPoint pt2)
{
// Returns the angle (radian) formed by the line pt1-pt2. The angle follows the same logic
// as in pointInCircle.
// What we do here is that we take the line and reduce it to fit a "unit circle" (circle with
// a radius of 1). Then, either asin(adjusted_dy) or acos(adjusted_dx) will give us our angle.
// We'll use asin(adjusted_dy).
CGFloat length = distance(pt1, pt2);
CGFloat dx = pt2.x - pt1.x;
CGFloat dy = pt2.y - pt1.y;
CGFloat ajdusted_dy = ABS(dy) / length;
CGFloat angle = asin(ajdusted_dy);
if ((dx < 0) && (dy >= 0)) {
// top-left quadrant
angle = M_PI - angle;
}
else if ((dx < 0) && (dy < 0)) {
// bottom-left quadrant
angle = M_PI + angle;
}
else if ((dx >= 0) && (dy < 0)) {
// bottom-right quadrant
angle = (2 * M_PI) - angle;
}
return angle;
}