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86 lines
2.5 KiB
Haxe
86 lines
2.5 KiB
Haxe
package funkin.util;
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import flixel.math.FlxPoint;
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/**
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* Utilities for performing math with bezier curves.
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*/
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class BezierUtil
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{
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/**
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* Linearly interpolate between two values.
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* Depending on p, 0 = a, 1 = b, 0.5 = halfway between a and b.
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*/
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static inline function mix2(p:Float, a:Float, b:Float):Float
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{
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return a * (1 - p) + (b * p);
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}
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/**
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* Linearly interpolate between three values.
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* Depending on p, 0 = a, 0.5 = b, 1 = c, 0.25 = halfway between a and b, etc.
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*/
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static inline function mix3(p:Float, a:Float, b:Float, c:Float):Float
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{
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return mix2(p, mix2(p, a, b), mix2(p, b, c));
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}
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static inline function mix4(p:Float, a:Float, b:Float, c:Float, d:Float):Float
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{
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return mix2(p, mix3(p, a, b, c), mix3(p, b, c, d));
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}
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static inline function mix5(p:Float, a:Float, b:Float, c:Float, d:Float, e:Float):Float
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{
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return mix2(p, mix4(p, a, b, c, d), mix4(p, b, c, d, e));
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}
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/**
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* A bezier curve with two points.
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* This is really just linear interpolation but whatever.
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*/
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public static function bezier2(p:Float, a:FlxPoint, b:FlxPoint):FlxPoint
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{
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return new FlxPoint(mix2(p, a.x, b.x), mix2(p, a.y, b.y));
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}
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/**
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* A bezier curve with three points.
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* @param p The percentage of the way through the curve.
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* @param a The start point.
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* @param b The control point.
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* @param c The end point.
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*/
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public static function bezier3(p:Float, a:FlxPoint, b:FlxPoint, c:FlxPoint):FlxPoint
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{
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return new FlxPoint(mix3(p, a.x, b.x, c.x), mix3(p, a.y, b.y, c.y));
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}
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/**
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* A bezier curve with four points.
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* @param p The percentage of the way through the curve.
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* @param a The start point.
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* @param b The first control point.
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* @param c The second control point.
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* @param d The end point.
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*/
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public static function bezier4(p:Float, a:FlxPoint, b:FlxPoint, c:FlxPoint, d:FlxPoint):FlxPoint
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{
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return new FlxPoint(mix4(p, a.x, b.x, c.x, d.x), mix4(p, a.y, b.y, c.y, d.y));
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}
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/**
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* A bezier curve with four points.
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* @param p The percentage of the way through the curve.
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* @param a The start point.
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* @param b The first control point.
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* @param c The second control point.
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* @param c The third control point.
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* @param d The end point.
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*/
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public static function bezier5(p:Float, a:FlxPoint, b:FlxPoint, c:FlxPoint, d:FlxPoint, e:FlxPoint):FlxPoint
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{
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return new FlxPoint(mix5(p, a.x, b.x, c.x, d.x, e.x), mix5(p, a.y, b.y, c.y, d.y, e.y));
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}
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}
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