/// <summary>
/// 计算一组三角形网格中每个顶点的Normal值
/// 1.对每个三角形片元分析，根据*三个顶点*的坐标位置计算出该片元的法向矢量
/// 2.将法向矢量赋值给三个顶点
/// 3.对有片元进行处理完毕后，每个顶点的normal值是所有*与之相邻的片元法向矢量的和*
/// 4.最后遍历每个顶点，对Norma值归一化即可
/// </summary>
/// <param name="inputVex"></param>
/// <param name="inputInd"></param>
public static void ComputeVertexNormal(ref MyVertex[] inputVex, int[] inputInd)
{
// 遍历每个三角形片元
for (int i = 0; i < inputInd.Length / 3; i++)
{
// 三角形对应的三个顶点索引
int i0 = inputInd[i * 3 + 0];
int i1 = inputInd[i * 3 + 1];
int i2 = inputInd[i * 3 + 2];
// 三角形三个顶点
MyVertex v0 = inputVex[i0];
MyVertex v1 = inputVex[i1];
MyVertex v2 = inputVex[i2];
// 计算平面法向矢量
Vector3 e0 = v1.Position - v0.Position;
Vector3 e1 = v2.Position - v0.Position;
Vector3 faceNormal = Vector3.Cross(e0, e1);
// 因为这个三角形占用了这三个顶点
// 因此这三个顶点的normal值应该添加该平面三角形的法线向量
inputVex[i0].Normal += faceNormal;
inputVex[i1].Normal += faceNormal;
inputVex[i2].Normal += faceNormal;
}
// 遍历每个顶点，将其Normal值归一化
for (int i = 0; i < inputVex.Length; i++)
{
inputVex[i].Normal = Vector3.Normalize(inputVex[i].Normal);
}
}
public static MeshData[] LoadModelFromFile(string filename)
{
var importer = new AssimpContext();
if (!importer.IsImportFormatSupported(System.IO.Path.GetExtension(filename)))
{
throw new ArgumentException($"Model format {System.IO.Path.GetExtension(filename)} is not supported. Cannot load {filename}.", nameof(filename));
}
var postProcessFlags = PostProcessSteps.GenerateSmoothNormals | PostProcessSteps.CalculateTangentSpace;
var model = importer.ImportFile(filename, postProcessFlags);
List <MeshData> meshDatas = new List <MeshData>(model.MeshCount);
MeshData meshData = new MeshData();
foreach (var mesh in model.Meshes)
{
List <MyVertex> myVertices = new List <MyVertex>(mesh.VertexCount);
for (int i = 0; i < mesh.VertexCount; i++)
{
var pos = mesh.HasVertices ? mesh.Vertices[i].ToVector3() : new Vector3();
var norm = mesh.HasNormals ? mesh.Normals[i] : new Vector3D();
var texC = mesh.HasTextureCoords(0) ? mesh.TextureCoordinateChannels[0][i] : new Vector3D(1, 1, 0);
var v = new MyVertex(pos, norm.ToVector3(), texC.ToVector2());
myVertices.Add(v);
}
var indices = mesh.GetIndices().ToList();
meshData.Vertices = myVertices.ToArray();
meshData.Indices = indices.ToArray();
meshDatas.Add(meshData);
}
return(meshDatas.ToArray());
}
/// <summary>
/// 生成平面
/// </summary>
/// <param name="length">平面长度 X方向</param>
/// <param name="width">平面宽度 Z方向</param>
/// <param name="lenNum">X方向切片数</param>
/// <param name="widNum">Z方向切片数</param>
/// <param name="outMesh">输出数据</param>
public static void GeneratePlane(float length, float width, int lenNum, int widNum, out MeshData outMesh)
{
//[0]顶点数据
List <MyVertex> tempVertice = new List <MyVertex>();
MyVertex tempVex;
lenNum += 1;
widNum += 1;
float dl = length / lenNum;
float dw = width / widNum;
float y = 0f;
for (int i = 0; i < lenNum; i++)
{
float x = -length / 2 + i * dl;
//第i列(从前往后)
for (int j = 0; j < widNum; j++)
{
//第j行(从左往右)
float z = -width / 2 + j * dw;
tempVex = new MyVertex();
tempVex.Position = new Vector3(x, y, z);
tempVex.Normal = new Vector3(0, 1, 0);
tempVertice.Add(tempVex);
}
}
//[1]索引数据
List <int> tempIndex = new List <int>();
for (int i = 0; i < lenNum - 1; i++)
{
//第i列(从前往后)
for (int j = 0; j < widNum - 1; j++)
{
//第j行(从左往右)
tempIndex.Add(i * widNum + j);
tempIndex.Add(i * widNum + j + 1);
tempIndex.Add((i + 1) * widNum + j + 1);
tempIndex.Add((i + 1) * widNum + j + 1);
tempIndex.Add((i + 1) * widNum + j);
tempIndex.Add(i * widNum + j);
}
}
outMesh.Indices = tempIndex.ToArray();
outMesh.Vertices = tempVertice.ToArray();
}
/// <summary>
/// 生成柱体
/// </summary>
/// <param name="topRadius">顶部半径</param>
/// <param name="bottomRadius">底部半径</param>
/// <param name="height">高度</param>
/// <param name="sliceCount">切片数</param>
/// <param name="stackCount">断层数</param>
/// <param name="outMesh">输出的MeshData网格结构</param>
public static void GenerateCylinder(float topRadius, float bottomRadius, float height, int sliceCount, int stackCount, out MeshData outMesh)
{
//[0] 侧面数据
// init meshdata size
var vertexsNum = (stackCount + 1) * (sliceCount + 1);
var indexNum = stackCount * sliceCount * 6;
outMesh = new MeshData(vertexsNum, indexNum);
// Stacks
float stackHeight = height / stackCount;
// radius increment
float radiusStep = (topRadius - bottomRadius) / stackCount;
// ring count
var ringCount = stackCount + 1;
int vetexNumber = 0;
float dTheta = 2.0f * (float)Math.PI / sliceCount;
// 层层建模 侧面顶点数据
for (int i = 0; i < ringCount; i++)
{
// 建模中心 y 在中心高度处，从低往高建
float y = -0.5f * height + i * stackHeight;
float r = bottomRadius + i * radiusStep;
// vertices
// 起始顶点和最终顶点只是位置一样，但顶点其它分量不同
for (int j = 0; j <= sliceCount; j++)
{
float c = (float)Math.Cos(j * dTheta);
float s = (float)Math.Sin(j * dTheta);
MyVertex myVertex = new MyVertex();
myVertex.Position = new Vector3(r * c, y, r * s);
float dr = bottomRadius - topRadius;
Vector3 bitangent = new Vector3(dr * c, -height, dr * s);
myVertex.Normal = Vector3.Normalize(Vector3.Cross(new Vector3(-s, 0f, c), bitangent));
outMesh.Vertices[vetexNumber] = myVertex;
vetexNumber++;
}
}
//[1] 修改索引
int number = 0;
int numsPerRing = sliceCount + 1;
for (int i = 0; i < stackCount; i++)
{
for (int j = 0; j < sliceCount; j++)
{
outMesh.Indices[number + 0] = i * numsPerRing + j;
outMesh.Indices[number + 1] = (i + 1) * numsPerRing + j;
outMesh.Indices[number + 2] = (i + 1) * numsPerRing + j + 1;
outMesh.Indices[number + 3] = (i + 1) * numsPerRing + j + 1;
outMesh.Indices[number + 4] = i * numsPerRing + j + 1;
outMesh.Indices[number + 5] = i * numsPerRing + j;
number += 6;
}
}
//[2] 顶面数据和索引
// 顶面顶点数据
List <MyVertex> tempVertex = outMesh.Vertices.ToList();
for (int i = 0; i <= sliceCount; i++)
{
float x = (float)(topRadius * Math.Cos(i * dTheta));
float z = (float)(topRadius * Math.Sin(i * dTheta));
MyVertex myVertex = new MyVertex();
myVertex.Position = new Vector3(x, 0.5f * height, z);
myVertex.Normal = new Vector3(0, 1, 0);
tempVertex.Add(myVertex);
}
// 顶点中心数据
var myVertexCenter = new MyVertex();
myVertexCenter.Position = new Vector3(0, 0.5f * height, 0);
myVertexCenter.Normal = new Vector3(0, 1, 0);
tempVertex.Add(myVertexCenter);
outMesh.Vertices = tempVertex.ToArray();
// 顶面索引
List <int> tempIndices = outMesh.Indices.ToList();
for (int i = 0; i <= sliceCount; i++)
{
tempIndices.Add(outMesh.Vertices.Length - 1);
tempIndices.Add(outMesh.Vertices.Length - 2 - i);
tempIndices.Add(outMesh.Vertices.Length - 1 - i);
}
outMesh.Indices = tempIndices.ToArray();
//[3] 底面数据和索引
// 底面顶点数据
tempVertex = outMesh.Vertices.ToList();
for (int i = 0; i <= sliceCount; i++)
{
float x = (float)(topRadius * Math.Cos(i * dTheta));
float z = (float)(topRadius * Math.Sin(i * dTheta));
MyVertex myVertex = new MyVertex();
myVertex.Position = new Vector3(x, -0.5f * height, z);
myVertex.Normal = new Vector3(0, -1, 0);
tempVertex.Add(myVertex);
}
// 顶点中心数据
myVertexCenter = new MyVertex();
myVertexCenter.Position = new Vector3(0, -0.5f * height, 0);
myVertexCenter.Normal = new Vector3(0, -1, 0);
tempVertex.Add(myVertexCenter);
outMesh.Vertices = tempVertex.ToArray();
// 顶面索引
tempIndices = outMesh.Indices.ToList();
for (int i = 0; i <= sliceCount; i++)
{
tempIndices.Add(outMesh.Vertices.Length - 1);
tempIndices.Add(outMesh.Vertices.Length - 2 - i);
tempIndices.Add(outMesh.Vertices.Length - 1 - i);
}
outMesh.Indices = tempIndices.ToArray();
}
/// <summary>
/// 生成球体
/// </summary>
/// <param name="rad">球体半径</param>
/// <param name="sliceNum">切片数</param>
/// <param name="stackNum">断层数</param>
/// <param name="sphereMesh">输出的MeshData网格结构</param>
public static void GenerateSphere(int rad, int sliceNum, int stackNum, out MeshData sphereMesh)
{
//[0]侧面
sphereMesh = new MeshData(1, 1);
float dTheta = 2.0f * (float)Math.PI / sliceNum;
float dPhi = (float)Math.PI / stackNum;
float Phi = 0;
var tempVertex = sphereMesh.Vertices.ToList();
tempVertex.Clear();
//[1]底部顶点
tempVertex.Add(new MyVertex()
{
Position = new Vector3(0, -rad, 0),
Normal = new Vector3(0, -1, 0),
});
float layerColor = 0f;
//[2]层层建模 侧面顶点数据
for (int i = 1; i < stackNum; i++)
{
// 建模中心 y 在中心高度处，从低往高建
float y = -rad * (float)Math.Cos(Phi + i * dPhi);
float r = rad * (float)Math.Sin(Phi + i * dPhi);
// 起始顶点和最终顶点只是位置一样，但顶点其它分量不同
for (int j = 0; j <= sliceNum; j++)
{
float c = (float)Math.Cos(j * dTheta);
float s = (float)Math.Sin(j * dTheta);
MyVertex myVertex = new MyVertex();
myVertex.Position = new Vector3(r * c, y, r * s);
myVertex.Normal = new Vector3(0, 1f, 0);
tempVertex.Add(myVertex);
}
layerColor += 0.1f;
}
//[3]顶部
tempVertex.Add(new MyVertex()
{
Position = new Vector3(0, rad, 0),
Normal = new Vector3(0, 1, 0),
});
sphereMesh.Vertices = tempVertex.ToArray();
//[4]索引部分
int numsPerRing = sliceNum + 1;
List <int> tempIndice = sphereMesh.Indices.ToList();
tempIndice.Clear();
int number = 0;
for (int i = 0; i < sliceNum; i++)
{
tempIndice.Add(0);
tempIndice.Add(number + 1);
tempIndice.Add(number + 2);
number += 1;
}
for (int i = 0; i < stackNum - 2; i++)
{
for (int j = 1; j <= sliceNum; j++)
{
tempIndice.Add(i * numsPerRing + j);
tempIndice.Add((i + 1) * numsPerRing + j);
tempIndice.Add((i + 1) * numsPerRing + j + 1);
tempIndice.Add((i + 1) * numsPerRing + j + 1);
tempIndice.Add(i * numsPerRing + j + 1);
tempIndice.Add(i * numsPerRing + j);
}
}
number = 0;
for (int i = 0; i < sliceNum; i++)
{
tempIndice.Add(sphereMesh.Vertices.Length - 1);
tempIndice.Add(sphereMesh.Vertices.Length - 2 - number);
tempIndice.Add(sphereMesh.Vertices.Length - 3 - number);
number += 1;
}
sphereMesh.Indices = tempIndice.ToArray();
}
