Mesh网格编程(一) 流体
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Mesh网格编程(一) 流体水
通过Mesh网格随Sin函数实时变化模拟液体的流动,从而达到动态水的效果。
效果图:
Mesh网格编程步骤:
一:确定数量
确定该几何图形应有多少个三角形面,顶点坐标、顶点序列、UV贴图、法线向量皆为三角形面数的三倍。
二:根据三角形面确定顶点坐标
这里我习惯把一个面的顶点确定好之后再去找下一个面,这样做可以是法线和顶点序列确定起来很容易。但是要注意的是在确定顶点时要按照顺时针顺序确定,否则会导致三角形面相反。
三:确定法线
法线大致分为两种:
其一是棱角分明的几何体,这种几何体的法线可以用确定好的顶点坐标两两相减,得到的向量做叉乘并赋值给三个顶点上的法线。
其二是圆滑的几何体,这种几何体需要求出该点在曲面上的切线,从而确定垂直于切线的法线。如果是圆形。可以使用顶点减圆心所得的向量。
此外,求得的法线尽量单位化,否则可能出现一个面上的颜色不同。
四:确定顶点序列
若三角形顶点按照面数去确定,顶点序列就会变得非常简单,按顺序赋值即可。
五:确定UV贴图
根据所做几何体的不同,贴图左边也会有所改变,并不固定。
六:创建网格
实现代码如下:
- using UnityEngine;
- using System.Collections;
-
- public class Water : MonoBehaviour {
-
- Mesh mesh;
-
- public int tier = 10;
- private float length = 10;
- private int width = 3;
- private int hight = 10;
-
- private Vector3[] vs;
- private int[] ts;
- private Vector2[] newUVs;
- private Vector3[] newNormals;
-
- void Update () {
-
- int temp = ((tier + 1) * 8 + 4) * 3;
-
- vs = new Vector3[temp];
- ts = new int[temp];
- newUVs = new Vector2[temp];
- newNormals = new Vector3[temp];
-
- float dis = 2 * Mathf.PI / tier;
-
- int count = 0;
- for (int i = 0; i < tier; i++) {
-
- float pos1 = i * length / tier - length / 2;
- float pos2 = (i + 1) * length / tier - length / 2;
-
- vs[count] = new Vector3(pos1,Mathf.Sin(Time.time + i * dis), width);
- vs[count + 1] = new Vector3(pos2,Mathf.Sin(Time.time + (i + 1) * dis), -width);
- vs[count + 2] = new Vector3(pos1,Mathf.Sin(Time.time + i * dis), -width);
-
- vs[count + 3] = new Vector3(pos1,Mathf.Sin(Time.time + i * dis), width);
- vs[count + 4] = new Vector3(pos2,Mathf.Sin(Time.time + (i + 1) * dis), width);
- vs[count + 5] = new Vector3(pos2,Mathf.Sin(Time.time + (i + 1) * dis), -width);
-
- newNormals[count] = Vector3.Normalize(new Vector3(1,Mathf.Cos(Time.time + i * dis), 0));
- newNormals[count + 1] = Vector3.Normalize(new Vector3(1,Mathf.Cos(Time.time + (i + 1) * dis), 0));
- newNormals[count + 2] = Vector3.Normalize(new Vector3(1,Mathf.Cos(Time.time + i * dis), 0));
-
- newNormals[count + 3] = Vector3.Normalize(new Vector3(1,Mathf.Cos(Time.time + i * dis), 0));
- newNormals[count + 4] = Vector3.Normalize(new Vector3(1,Mathf.Cos(Time.time + (i + 1) * dis), 0));
- newNormals[count + 5] = Vector3.Normalize(new Vector3(1,Mathf.Cos(Time.time + (i + 1) * dis), 0));
-
-
- vs[count + 6] = new Vector3(pos1,Mathf.Sin(Time.time + i * dis), -width);
- vs[count + 7] = new Vector3(pos2,-hight, -width);
- vs[count + 8] = new Vector3(pos1,-hight, -width);
-
- vs[count + 9] = new Vector3(pos1,Mathf.Sin(Time.time + i * dis), -width);
- vs[count + 10] = new Vector3(pos2,Mathf.Sin(Time.time + (i + 1) * dis), -width);
- vs[count + 11] = new Vector3(pos2,-hight, -width);
-
- for (int j = 0; j < 6; j++) {
- newNormals[count + 6 + j] = Vector3.back;
- }
-
- vs[count + 12] = new Vector3(pos1,Mathf.Sin(Time.time + i * dis), width);
- vs[count + 13] = new Vector3(pos1,-hight, width);
- vs[count + 14] = new Vector3(pos2,-hight, width);
-
- vs[count + 15] = new Vector3(pos1,Mathf.Sin(Time.time + i * dis), width);
- vs[count + 16] = new Vector3(pos2,-hight, width);
- vs[count + 17] = new Vector3(pos2,Mathf.Sin(Time.time + (i + 1) * dis), width);
-
- for (int j = 0; j < 6; j++) {
- newNormals[count + 12 + j] = Vector3.forward;
- }
-
- vs[count + 18] = new Vector3(pos1,-hight, width);
- vs[count + 19] = new Vector3(pos1,-hight, -width);
- vs[count + 20] = new Vector3(pos2,-hight, -width);
-
- vs[count + 21] = new Vector3(pos1,-hight, width);
- vs[count + 22] = new Vector3(pos2,-hight, -width);
- vs[count + 23] = new Vector3(pos2,-hight, width);
-
- for (int j = 0; j < 6; j++) {
- newNormals[count + 18 + j] = Vector3.down;
- }
-
- count += 24;
- }
-
-
- vs [vs.Length - 12] = new Vector3 (-length / 2, Mathf.Sin (Time.time), width);
- vs [vs.Length - 11] = new Vector3 (-length / 2, -hight, -width);
- vs [vs.Length - 10] = new Vector3 (-length / 2, -hight, width);
-
- vs [vs.Length - 9] = new Vector3 (-length / 2, Mathf.Sin (Time.time), width);
- vs [vs.Length - 8] = new Vector3 (-length / 2, Mathf.Sin (Time.time), -width);
- vs [vs.Length - 7] = new Vector3 (-length / 2, -hight, -width);
-
- for (int j = 0; j < 6; j++) {
- newNormals[vs.Length - 12 + j] = Vector3.left;
- }
-
- vs [vs.Length - 6] = new Vector3 (length / 2, Mathf.Sin (Time.time + tier * dis), width);
- vs [vs.Length - 5] = new Vector3 (length / 2, -hight, width);
- vs [vs.Length - 4] = new Vector3 (length / 2, -hight, -width);
-
- vs [vs.Length - 3] = new Vector3 (length / 2, Mathf.Sin (Time.time + tier * dis), width);
- vs [vs.Length - 2] = new Vector3 (length / 2, -hight, -width);
- vs [vs.Length - 1] = new Vector3 (length / 2, Mathf.Sin (Time.time + tier * dis), -width);
-
- for (int j = 0; j < 6; j++) {
- newNormals[vs.Length - 6 + j] = Vector3.right;
- }
-
- for (int i = 0; i < ts.Length; i++) {
- ts[i] = i;
- }
-
- mesh = new Mesh();
- GetComponent<MeshFilter>().mesh = mesh;
- mesh.vertices = vs;
- mesh.uv = newUVs;
- mesh.triangles = ts;
- mesh.normals = newNormals;
- }
- }
注:波浪上方的面为曲面,故使用切线求法线。其他面很有规则,并没有使用叉乘的方法。
几何体没有使用UV贴图,newUVs没有赋值。
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