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POPerformance for checking if a point is inside a triangle (3D)
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19289979
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2013-10-10T07:49:30.113
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2013-10-10T14:52:00.080
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Body
I am in pursuit of a lightning fast java method to check if a point is inside a triangle. I found the following c++ code in a paper from Kasper Fauerby: <pre><code>typedef unsigned int uint32; #define in(a) ((uint32&) a) bool checkPointInTriangle(const VECTOR& point, const VECTOR& pa,const VECTOR& pb, const VECTOR& pc) { VECTOR e10=pb-pa; VECTOR e20=pc-pa; float a = e10.dot(e10); float b = e10.dot(e20); float c = e20.dot(e20); float ac_bb=(a*c)-(b*b); VECTOR vp(point.x-pa.x, point.y-pa.y, point.z-pa.z); float d = vp.dot(e10); float e = vp.dot(e20); float x = (d*c)-(e*b); float y = (e*a)-(d*b); float z = x+y-ac_bb; return (( in(z)& ~(in(x)|in(y)) ) & 0x80000000); } </code></pre> I was wondering if this code snippet could be converted to java, and if so, if it would outperform my Java code: <pre><code>public class Util { public static boolean checkPointInTriangle(Vector p1, Vector p2, Vector p3, Vector point) { float angles = 0; Vector v1 = Vector.min(point, p1); v1.normalize(); Vector v2 = Vector.min(point, p2); v2.normalize(); Vector v3 = Vector.min(point, p3); v3.normalize(); angles += Math.acos(Vector.dot(v1, v2)); angles += Math.acos(Vector.dot(v2, v3)); angles += Math.acos(Vector.dot(v3, v1)); return (Math.abs(angles - 2*Math.PI) <= 0.005); } public static void main(String [] args) { Vector p1 = new Vector(4.5f, 0, 0); Vector p2 = new Vector(0, -9f, 0); Vector p3 = new Vector(0, 0, 4.5f); Vector point = new Vector(2, -4, 0.5f); System.out.println(checkPointInTriangle(p1, p2, p3, point)); } } </code></pre> and the Vector class: <pre><code>public class Vector { public float x, y, z; public Vector(float x, float y, float z) { this.x = x; this.y = y; this.z = z; } public float length() { return (float) Math.sqrt(x*x + y*y + z*z); } public void normalize() { float l = length(); x /= l; y /= l; z /= l; } public static float dot(Vector one, Vector two) { return one.x*two.x + one.y*two.y + one.z*two.z; } public static Vector min(Vector one, Vector two) { return new Vector(one.x-two.x, one.y-two.y, one.z-two.z); } } </code></pre> or is there an even faster method for Java? Thanks in advance!
Tags
<java><c++><math><vector><3d>
Title
Performance for checking if a point is inside a triangle (3D)
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PostAcceptedAnswerId
1. PO
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1. This table or related slice is empty.
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1. PTQuestion
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1. This table or related slice is empty.
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1. USWilco
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1. PL
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1. This table or related slice is empty.
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1. PO
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1. This table or related slice is empty.
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