Check out example codes for "polygon triangulation unity". It will help you in understanding the concepts better.

Code Example 1

``````#pragma strict

import System.Collections.Generic;

public class Triangulator {

private var m_points:List.<Vector2> = new List.<Vector2>();

public function Triangulator(points:Vector2[]) {
m_points = new List.<Vector2>(points);
}

public function Triangulate() {
var indices:List.<int> = new List.<int>();

var n:int = m_points.Count;
if (n < 3)
return indices.ToArray();

var V:int[] = new int[n];
if (Area() > 0)
{
for (var v:int = 0; v < n; v++)
V[v] = v;
}
else {
for (v = 0; v < n; v++)
V[v] = (n - 1) - v;
}

var nv:int = n;
var count:int = 2 * nv;
var m=0;
for (v = nv - 1; nv > 2; )
{
if ((count--) <= 0)
return indices.ToArray();

var u:int = v;
if (nv <= u)
u = 0;
v = u + 1;
if (nv <= v)
v = 0;
var w:int = v + 1;
if (nv <= w)
w = 0;

if (Snip(u, v, w, nv, V))
{
var a:int;
var b:int;
var c:int;
var s:int;
var t:int;
a = V[u];
b = V[v];
c = V[w];
m++;
s = v;
for (t = v + 1; t < nv; t++)
{
V[s] = V[t];
s++;
}
nv--;
count = 2 * nv;
}
}

indices.Reverse();
return indices.ToArray();
}

private function Area () {
var n:int = m_points.Count;
var A:float = 0.0f;
var q:int=0;
for (var p:int = n - 1; q < n; p = q++) {
var pval:Vector2 = m_points[p];
var qval:Vector2 = m_points[q];
A += pval.x * qval.y - qval.x * pval.y;
}
return (A * 0.5);
}

private function Snip (u:int, v:int, w:int, n:int, V:int[]) {
var p:int;
var A:Vector2 = m_points[V[u]];
var B:Vector2 = m_points[V[v]];
var C:Vector2 = m_points[V[w]];
if (Mathf.Epsilon > (((B.x - A.x) * (C.y - A.y)) - ((B.y - A.y) * (C.x - A.x))))
return false;
for (p = 0; p < n; p++) {
if ((p == u) || (p == v) || (p == w))
continue;
var P:Vector2 = m_points[V[p]];
if (InsideTriangle(A, B, C, P))
return false;
}
return true;
}

private function InsideTriangle (A:Vector2, B:Vector2, C:Vector2, P:Vector2) {
var ax:float;
var ay:float;
var bx:float;
var by:float;
var cx:float;
var cy:float;
var apx:float;
var apy:float;
var bpx:float;
var bpy:float;
var cpx:float;
var cpy:float;
var cCROSSap:float;
var bCROSScp:float;
var aCROSSbp:float;

ax = C.x - B.x; ay = C.y - B.y;
bx = A.x - C.x; by = A.y - C.y;
cx = B.x - A.x; cy = B.y - A.y;
apx = P.x - A.x; apy = P.y - A.y;
bpx = P.x - B.x; bpy = P.y - B.y;
cpx = P.x - C.x; cpy = P.y - C.y;

aCROSSbp = ax * bpy - ay * bpx;
cCROSSap = cx * apy - cy * apx;
bCROSScp = bx * cpy - by * cpx;

return ((aCROSSbp >= 0.0) && (bCROSScp >= 0.0) && (cCROSSap >= 0.0));
}
}``````

Code Example 2

``````using UnityEngine;
using System.Collections.Generic;

public class Triangulator
{
private List<Vector2> m_points = new List<Vector2>();

public Triangulator (Vector2[] points) {
m_points = new List<Vector2>(points);
}

public int[] Triangulate() {
List<int> indices = new List<int>();

int n = m_points.Count;
if (n < 3)
return indices.ToArray();

int[] V = new int[n];
if (Area() > 0) {
for (int v = 0; v < n; v++)
V[v] = v;
}
else {
for (int v = 0; v < n; v++)
V[v] = (n - 1) - v;
}

int nv = n;
int count = 2 * nv;
for (int v = nv - 1; nv > 2; ) {
if ((count--) <= 0)
return indices.ToArray();

int u = v;
if (nv <= u)
u = 0;
v = u + 1;
if (nv <= v)
v = 0;
int w = v + 1;
if (nv <= w)
w = 0;

if (Snip(u, v, w, nv, V)) {
int a, b, c, s, t;
a = V[u];
b = V[v];
c = V[w];
for (s = v, t = v + 1; t < nv; s++, t++)
V[s] = V[t];
nv--;
count = 2 * nv;
}
}

indices.Reverse();
return indices.ToArray();
}

private float Area () {
int n = m_points.Count;
float A = 0.0f;
for (int p = n - 1, q = 0; q < n; p = q++) {
Vector2 pval = m_points[p];
Vector2 qval = m_points[q];
A += pval.x * qval.y - qval.x * pval.y;
}
return (A * 0.5f);
}

private bool Snip (int u, int v, int w, int n, int[] V) {
int p;
Vector2 A = m_points[V[u]];
Vector2 B = m_points[V[v]];
Vector2 C = m_points[V[w]];
if (Mathf.Epsilon > (((B.x - A.x) * (C.y - A.y)) - ((B.y - A.y) * (C.x - A.x))))
return false;
for (p = 0; p < n; p++) {
if ((p == u) || (p == v) || (p == w))
continue;
Vector2 P = m_points[V[p]];
if (InsideTriangle(A, B, C, P))
return false;
}
return true;
}

private bool InsideTriangle (Vector2 A, Vector2 B, Vector2 C, Vector2 P) {
float ax, ay, bx, by, cx, cy, apx, apy, bpx, bpy, cpx, cpy;
float cCROSSap, bCROSScp, aCROSSbp;

ax = C.x - B.x; ay = C.y - B.y;
bx = A.x - C.x; by = A.y - C.y;
cx = B.x - A.x; cy = B.y - A.y;
apx = P.x - A.x; apy = P.y - A.y;
bpx = P.x - B.x; bpy = P.y - B.y;
cpx = P.x - C.x; cpy = P.y - C.y;

aCROSSbp = ax * bpy - ay * bpx;
cCROSSap = cx * apy - cy * apx;
bCROSScp = bx * cpy - by * cpx;

return ((aCROSSbp >= 0.0f) && (bCROSScp >= 0.0f) && (cCROSSap >= 0.0f));
}
}``````

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