根据顶点列表生成三角形数组
根据顶点列表生成三角形数组
Triangulator.cs
using UnityEngine;
using System.Collections.Generic;
public class Triangulator
{
private static List<Vector2> points;
private static Vector3 cameraPosition;
public static Vector2[] ToVector2(Vector3[] m_points)
{
Vector2[] vertices2d = new Vector2[m_points.Length];
for (int i = 0; i < m_points.Length; i++)
{
Vector3 pos = m_points[i];
vertices2d[i] = new Vector2(pos.x, pos.z);
}
return vertices2d;
}
public static int[] Triangulate(Vector2[] m_points, Vector3 m_cameraPosition)
{
points = new List<Vector2>(m_points);
cameraPosition = m_cameraPosition;
List<int> indices = new List<int>();
int n = 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 m = 0, v = nv - 1; nv > 2;)
{
if ((count--) <= 0)
break;
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];
indices.Add(a);
indices.Add(b);
indices.Add(c);
m++;
for (s = v, t = v + 1; t < nv; s++, t++)
V[s] = V[t];
nv--;
count = 2 * nv;
}
}
bool reversFlag = true;
int i0 = indices[0];
int i1 = indices[1];
int i2 = indices[2];
Vector3 pos0 = new Vector3(points[i0].x, 0f, points[i0].y);
Vector3 pos1 = new Vector3(points[i1].x, 0f, points[i1].y);
Vector3 pos2 = new Vector3(points[i2].x, 0f, points[i2].y);
Vector3 v1 = pos1 - pos0;
Vector3 v2 = pos2 - pos1;
Vector3 crossVec = Vector3.Cross(v1, v2);
if (Vector3.Dot(cameraPosition, crossVec) > 0)
{
reversFlag = false;
}
if (reversFlag)
{
indices.Reverse();
}
return indices.ToArray();
}
private static float Area()
{
int n = points.Count;
float A = 0.0f;
for (int p = n - 1, q = 0; q < n; p = q++)
{
Vector2 pval = points[p];
Vector2 qval = points[q];
A += pval.x * qval.y - qval.x * pval.y;
}
return (A * 0.5f);
}
private static bool Snip(int u, int v, int w, int n, int[] V)
{
int p;
Vector2 A = points[V[u]];
Vector2 B = points[V[v]];
Vector2 C = 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 = points[V[p]];
if (InsideTriangle(A, B, C, P))
return false;
}
return true;
}
private static 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));
}
}
mesh.triangles = Triangulator.Triangulate(Triangulator.ToVector2(points), Camera.main.transform.position);