Since many students did not make it, we hereby post a Demo project (version Unity2019.1.8f1)
CSDN download: https://download.csdn.net/download/linxinfa/11956009
In addition, I also uploaded the Demo project to GitHub, (Unity version: 2020.1.2f1c1) can be downloaded directly on GitHub: https://github.com/linxinfa/Unity-ArbitraryPolygonMesh
scenes to be used
Radar chart
principle
It is to dynamically new a Mesh, set the triangle and fixed-point data, and then assign it to the MeshFilter, and draw it through the MeshRenderer
step
1 Copy the script below the article to the project
2 Create an empty object in the scene, name it Mesh, and hang the PolygonDrawer component
3 Create N Spheres under the Mesh object
4 Create a shader, select the shader you need, for example, the following is Unlit/Color, and adjust the color to blue
5 Assign the shader to the PolygonDrawer component
6 Assign N Spheres to the PolygonDrawer component (note the placement of N Spheres, the script in this article only supports clockwise or counterclockwise order)
7 Run Unity, pay attention to running before you can see the dynamically constructed polygon Mesh effect
supplement
Some students in the comment area said there was a problem. I tried it with Unity5.x, Unity2017 and Unity2019, and they all can be displayed normally.
The effect is as follows
Code
MethodExtensionForUnity.cs
using UnityEngine;
//Unity的一些扩展方法
static public class MethodExtensionForUnity
{
/// <summary>
/// Gets or add a component. Usage example:
/// BoxCollider boxCollider = transform.GetOrAddComponent<BoxCollider>();
/// </summary>
static public T GetOrAddComponent<T>(this Component child, bool set_enable = false) where T : Component
{
T result = child.GetComponent<T>();
if (result == null)
{
result = child.gameObject.AddComponent<T>();
}
var bcomp = result as Behaviour;
if (set_enable)
{
if (bcomp != null) bcomp.enabled = true;
}
return result;
}
static public T GetOrAddComponent<T>(this GameObject go) where T : Component
{
T result = go.transform.GetComponent<T>();
if (result == null)
{
result = go.AddComponent<T>();
}
var bcomp = result as Behaviour;
if (bcomp != null) bcomp.enabled = true;
return result;
}
public static void walk(this GameObject o, System.Action<GameObject> f)
{
f(o);
int numChildren = o.transform.childCount;
for (int i = 0; i < numChildren; ++i)
{
walk(o.transform.GetChild(i).gameObject, f);
}
}
}
Triangulator.cs
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 m = 0, 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];
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;
}
}
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));
}
}PolygonDrawer.cs
using UnityEngine;
/// <summary>
/// 绘制多边形
/// TODO: 存在两点重合时绘制有问题
/// </summary>
public class PolygonDrawer : MonoBehaviour
{
public Material material;
public Transform[] vertices;
private MeshRenderer mRenderer;
private MeshFilter mFilter;
void Start()
{
Draw();
}
void Update()
{
Draw();
}
[ContextMenu("Draw")]
public void Draw()
{
Vector2[] vertices2D = new Vector2[vertices.Length];
Vector3[] vertices3D = new Vector3[vertices.Length];
for (int i = 0; i < vertices.Length; i++)
{
Vector3 vertice = vertices[i].localPosition;
vertices2D[i] = new Vector2(vertice.x, vertice.y);
vertices3D[i] = vertice;
}
Triangulator tr = new Triangulator(vertices2D);
int[] triangles = tr.Triangulate();
Mesh mesh = new Mesh();
mesh.vertices = vertices3D;
mesh.triangles = triangles;
if (mRenderer == null)
{
mRenderer = gameObject.GetOrAddComponent<MeshRenderer>();
}
mRenderer.material = material;
if (mFilter == null)
{
mFilter = gameObject.GetOrAddComponent<MeshFilter>();
}
mFilter.mesh = mesh;
}
}