【边玩边学Unity3d】实现可编辑网格

之前简单了解了Unity中的网格信息由gameObject的MeshFilter组件中的Mesh属性实现访问，接下来就尝试实现网格的动态编辑。在这里，“网格可编辑”由鼠标拖拽网格顶点，或长按网格边界添加新顶点后重新绘制网格等两个简单操作实现。方便起见，所有实现限定在二维空间中。

先上张完成效果图：

先从最简单的开始，编写一个可拖拽的顶点对象来熟悉自定义网格。新建空对象，添加MeshFilter组件（一个Mesh属性为Null的组件，在运行时由脚本添加具体Mesh）、MeshShader组件（实现具体的绘制，随便找个内建材质试试看先吧）、BoxColloder组件（碰撞器，用于实现鼠标点击判断。size属性先手工调整为1.0×1.0×1.0），以及新建的“Vertex”脚本（该脚本实现将附加对象的MeshFilter组件的Mesh定义为一个0.1×0.1的矩形）。完成后将其添加为预设Vertex Prefab， 以供多次实例化调用。

脚本如下：

using UnityEngine;
using System.Collections;

public class Vertex : MonoBehaviour {
	
        private const float size = 0.05f;
	private Vector3[] newVertices = {
		new Vector3(size, -size, 0),
		new Vector3(size, size, 0),	
		new Vector3(-size, size, 0),
		new Vector3(-size, -size, 0)
	};
	
        private Vector2[] newUV = {
		new Vector2(0, 0),
		new Vector2(0, 1),
		new Vector2(1, 1),
		new Vector2(1, 0)
	};
	
        private int[] newTriangles = {0, 3, 2, 0, 2, 1};
	
	private Vector3[] newNormals = {Vector3.forward, Vector3.forward, Vector3.forward, Vector3.forward};//forward
	
	private Vector4[] newTangents = {
		new Vector4(-1, 0, 0, -1),
		new Vector4(-1, 0, 0, -1),
		new Vector4(-1, 0, 0, -1),
		new Vector4(-1, 0, 0, -1)
	};
	
	// Use this for initialization
	void Start () {
                Mesh mesh = new Mesh();
                GetComponent<MeshFilter>().mesh = mesh;
                mesh.vertices = newVertices;
                mesh.uv = newUV;
                mesh.triangles = newTriangles;		
                mesh.normals = newNormals;
                mesh.tangents = newTangents;
		
	}
	
}

然后，是Edge Prefab预设，即实现两端顶点位置改变时可以更新自身网格顶点位置，且在鼠标长按后实现添加顶点的边对象。该对象组件与Vertex Prefab大致相同，其脚本“Edge”中多了起始和终止顶点属性，以及计算自己网格顶点的CalcuVertexPosition方法。

脚本如下：

using UnityEngine;
using System.Collections;

public class Edge : MonoBehaviour {

	private GameObject startVertex;
	private GameObject endVertex;
	
	private Vector3[] newVertices = new Vector3[4];
	private const float size = 0.01f;
	private Vector3[] basicVertices = {
		new Vector3(size, 0, 0),
		new Vector3(size, 0, 0),	
		new Vector3(-size, 0, 0),
		new Vector3(-size, 0, 0)
	};
		
    private Vector2[] newUV = {
		new Vector2(1, 1),
		new Vector2(0, 1),
		new Vector2(0, 0),
		new Vector2(1, 0)
	};
	
    private int[] newTriangles =  {0, 3, 2, 0, 2, 1};
	
	private Vector3[] newNormals = {Vector3.forward, Vector3.forward, Vector3.forward, Vector3.forward};
	
	private Vector4[] newTangents = {
		new Vector4(-1, 0, 0, -1),
		new Vector4(-1, 0, 0, -1),
		new Vector4(-1, 0, 0, -1),
		new Vector4(-1, 0, 0, -1)
	};
	
	public GameObject StartVertex {
		get {return startVertex;}
		set {startVertex = value;}
	}
	
	public GameObject EndVertex {
		get {return endVertex;}
		set {endVertex = value;}
	}
		
	public void CalcuVertexPosition () {
		
		if(startVertex == null || endVertex == null){
			return;
		}
		
		Vector3 startPosition = startVertex.transform.localPosition;
		Vector3 endPosition = endVertex.transform.localPosition;
		
		float length = Vector3.Distance(startPosition, endPosition) - 0.04f;
		float halfLength = length * 0.5f;
		
		Vector3 position = (endPosition + startPosition)*0.5f;		
		Quaternion rotation = Quaternion.FromToRotation(Vector3.up, startPosition - endPosition );
				
		gameObject.transform.localPosition = position;
		gameObject.transform.localRotation = rotation;
		
		BoxCollider collider = GetComponent<BoxCollider>();		
		collider.size = new Vector3(0.02f, length, 0.02f);
		
		newVertices[0] = halfLength*Vector3.down + basicVertices[0];
		newVertices[1] = halfLength*Vector3.up + basicVertices[1];
		newVertices[2] = halfLength*Vector3.up + basicVertices[2];
		newVertices[3] = halfLength*Vector3.down + basicVertices[3];
		
		ResetMesh();
		
	}
	
	public void ResetMesh(){
                Mesh mesh = new Mesh();
                GetComponent<MeshFilter>().mesh = mesh;
                mesh.vertices = newVertices;
                mesh.uv = newUV;
                mesh.triangles = newTriangles;
		
                mesh.normals = newNormals;
                mesh.tangents = newTangents;
		
	}
	
}

先到这里，下一篇完成MeshObject对象，以及MeshBuilder、MeshEditor脚本。