之前在

Unity Mesh(三) Mesh画球

中已经说明了如何画球，现在我们在这个球的基础上贴图。

这里我们有个极坐标和直角坐标的转换，具体我也不是很明白，反正就是拿来用吧，据某位大神讲解，极坐标（球坐标）由球半径，水平角和垂直角决定，我们完全可以理解为三维坐标转换成uv坐标的方程，也就是三维坐标映射到uv坐标上，f(u,v)=[x,y,z]这样的一个映射关系，映射关系取决于函数具体怎么定义的或者这个球是怎么画的，不同的模型有不同的方法，典型的克莱因瓶一个uv完整的模型，它有自己的函数。

好了，楼主还是参考的Jasper Flick的方法，这个大神一直很崇拜。

f(u,v)=[x,y,z]

u=asin(y) / π + ½.

v=atan2(x, z) / -2π

unity自带的球贴图会在两个极点出现扭曲Twisting的现象：

包括我们之前建立的球也没有考虑到这一个点，原因是计算极点的坐标时，极点只有一个坐标，但是极点每个四分之一圆实际上是我们极点四个三角形公用了一个uv坐标，这样就会造成扭曲现象，解决方法是我们把极点的点拆分成四个相同的点，一个面一个。

这样的话，我们之前画球的点稍稍有改动，上下两个极点分别加三个点。

这样这个问题就解决了！

下面我们直接上图：

这个最后的完整代码如下：

using UnityEngine;
using System.Collections;[RequireComponent(typeof(MeshFilter), typeof(MeshRenderer))]
public class DrawOctahedronSphere : MonoBehaviour
{public Material mat;public int subdivisions;public int radius;private static Vector3[] directions = {Vector3.left,Vector3.back,Vector3.right,Vector3.forward};void Start(){DrawSphere(subdivisions, radius);}public void DrawSphere(int subdivisions = 0, float radius = 1){if (subdivisions > 4){subdivisions = 4;}gameObject.GetComponent<MeshRenderer>().material = mat;Mesh mesh = GetComponent<MeshFilter>().mesh;mesh.Clear();int resolution = 1 << subdivisions;Vector3[] vertices = new Vector3[(resolution + 1) * (resolution + 1) * 4 - 3 * (resolution * 2 - 1)];int[] triangles = new int[(1 << (subdivisions * 2 + 3)) * 3];CreateOctahedron(vertices, triangles, resolution);if (radius != 1f){for (int i = 0; i < vertices.Length; i++){vertices[i] *= radius;}}Vector3[] normals = new Vector3[vertices.Length];Normalize(vertices, normals);Vector2[] uv = new Vector2[vertices.Length];CreateUV(vertices, uv);mesh.vertices = vertices;mesh.triangles = triangles;mesh.normals = normals;mesh.uv = uv;}private static void CreateOctahedron(Vector3[] vertices, int[] triangles, int resolution){int v = 0, vBottom = 0, t = 0;for (int i = 0; i < 4; i++){vertices[v++] = Vector3.down;}for (int i = 1; i <= resolution; i++){float progress = (float)i / resolution;Vector3 from, to;vertices[v++] = to = Vector3.Lerp(Vector3.down, Vector3.forward, progress);for (int d = 0; d < 4; d++){from = to;to = Vector3.Lerp(Vector3.down, directions[d], progress);t = CreateLowerStrip(i, v, vBottom, t, triangles);v = CreateVertexLine(from, to, i, v, vertices);vBottom += i > 1 ? (i - 1) : 1;}vBottom = v - 1 - i * 4;}for (int i = resolution - 1; i >= 1; i--){float progress = (float)i / resolution;Vector3 from, to;vertices[v++] = to = Vector3.Lerp(Vector3.up, Vector3.forward, progress);for (int d = 0; d < 4; d++){from = to;to = Vector3.Lerp(Vector3.up, directions[d], progress);t = CreateUpperStrip(i, v, vBottom, t, triangles);v = CreateVertexLine(from, to, i, v, vertices);vBottom += i + 1;}vBottom = v - 1 - i * 4;}for (int i = 0; i < 4; i++){triangles[t++] = vBottom;triangles[t++] = v;triangles[t++] = ++vBottom;vertices[v++] = Vector3.up;}}private static int CreateVertexLine(Vector3 from, Vector3 to, int steps, int v, Vector3[] vertices){for (int i = 1; i <= steps; i++){vertices[v++] = Vector3.Lerp(from, to, (float)i / steps);}return v;}private static int CreateLowerStrip(int steps, int vTop, int vBottom, int t, int[] triangles){for (int i = 1; i < steps; i++){triangles[t++] = vBottom;triangles[t++] = vTop - 1;triangles[t++] = vTop;triangles[t++] = vBottom++;triangles[t++] = vTop++;triangles[t++] = vBottom;}triangles[t++] = vBottom;triangles[t++] = vTop - 1;triangles[t++] = vTop;return t;}private static int CreateUpperStrip(int steps, int vTop, int vBottom, int t, int[] triangles){triangles[t++] = vBottom;triangles[t++] = vTop - 1;triangles[t++] = ++vBottom;for (int i = 1; i <= steps; i++){triangles[t++] = vTop - 1;triangles[t++] = vTop;triangles[t++] = vBottom;triangles[t++] = vBottom;triangles[t++] = vTop++;triangles[t++] = ++vBottom;}return t;}private static void Normalize(Vector3[] vertices, Vector3[] normals){for (int i = 0; i < vertices.Length; i++){normals[i] = vertices[i] = vertices[i].normalized;}}private static void CreateUV(Vector3[] vertices, Vector2[] uv){float previousX = 1f;for (int i = 0; i < vertices.Length; i++){Vector3 v = vertices[i];if (v.x == previousX){uv[i - 1].x = 1f;}previousX = v.x;Vector2 textureCoordinates;textureCoordinates.x = Mathf.Atan2(v.x, v.z) / (-2f * Mathf.PI);if (textureCoordinates.x < 0f){textureCoordinates.x += 1f;}textureCoordinates.y = Mathf.Asin(v.y) / Mathf.PI + 0.5f;uv[i] = textureCoordinates;}uv[vertices.Length - 4].x = uv[0].x = 0.125f;uv[vertices.Length - 3].x = uv[1].x = 0.375f;uv[vertices.Length - 2].x = uv[2].x = 0.625f;uv[vertices.Length - 1].x = uv[3].x = 0.875f;}
}

Unity Mesh(七) Mesh给球贴图相关推荐

Unity动态构建Mesh来绘制任意多边形（雷达图效果）
由于很多同学没有做出来,特此补传一个Demo工程 (版本Unity2019.1.8f1) CSDN下载:https://download.csdn.net/download/linxinfa/1195 ...
Unity Mesh(五) Mesh 立方体Cube贴图以及六个面分别贴不同的图片
在前面的篇章中已经有了怎么Mesh画一个立方体,当时的立方体是按照逆时针的画的,其它大都都是按照顺时针画的,当时一开始画立方体顺时针没画出来,有些面看不到就调换了下顺序,没特别注意方向问题,然而这一篇 ...
unity Text Mesh Pro Sprite Animation 支持动图，动态表情
unity Text Mesh Pro Sprite Animation 支持动图,动态表情使用格式 <sprite='assetName' anim='first frame, last f ...
Unity网格篇Mesh（一）
程序代码实现网格这里根据CSDNSpring5211的一篇文章,进行网格学习为网格材质合并作为一个基础本文的目标创建网格坐标使用携程计算他们位置利用三角形确定一个面自动生成法线添加纹理坐 ...
Unity学习笔记——Mesh
Unity学习笔记--Mesh Unity中的Mesh组件是一个很好玩的东西,这次的目标是根据高程图创建出一个平面. 1.用脚本创建一个简单的三角形新建空的物体,挂上MeshFilter.MeshR ...
Unity使用Skinned Mesh Renederer的BlendShapes时，报错“Platform does not support compute shaders”
Unity使用Skinned Mesh Renederer的BlendShapes时,报错"Platform does not support compute shaders" 报 ...
Unity优化篇——mesh合并
一.mesh合并大体分为: 1.合并网格 2.合并贴图 3.附加材质 4.重新计算UV 这里提一下附加材质,附加材质是对合并后的mesh重新赋予了一个material.废话不多说上代码! 备注:代码大 ...
【Unity】获取模型的材质球贴图中的像素点色值
获取模型的材质球贴图中的像素点色值,可以计算模型贴图的RGB.或某个色值的占比,也可以动态修改指定像素色值. 方式一: 获取可读的贴图,并遍历像素点:(通过Texture获取Texture2D操作的运 ...
Not allowed to access normals on mesh ‘Combined Mesh (root: scene)‘ (isReadable is false...报错解决方法
Unity播放时如果出现的"Not allowed to access normals on mesh 'Combined Mesh (root: scene)' (isReadable ...

Unity Mesh(七) Mesh给球贴图

Unity Mesh(三) Mesh画球

Unity Mesh(七) Mesh给球贴图相关推荐

最新文章

热门文章