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