private Mesh GenerateLod(LODTopologyOptions lod, int index)
{
var mesh = new Mesh {
name = "Procedural Grass " + index
};
int numVerticesPerPlane = (lod.verticesX + 1) * (lod.verticesY + 1);
Vector3[] vertices = new Vector3[numVerticesPerPlane * lod.planeCount];
Vector3[] normals = new Vector3[vertices.Length];
Vector2[] uv = new Vector2[vertices.Length];
Vector4[] tangents = new Vector4[vertices.Length];
int[] triangles = new int[lod.verticesX * lod.verticesY * lod.planeCount * 6];
for (int planeIndex = 0; planeIndex < lod.planeCount; ++planeIndex)
{
float planeRotation = Mathf.PI / lod.planeCount * planeIndex;
GeneratePlane(lod, vertices, normals, uv, tangents, triangles, planeIndex, planeRotation);
}
mesh.vertices = vertices;
mesh.normals = normals;
mesh.uv = uv;
mesh.tangents = tangents;
mesh.triangles = triangles;
return(mesh);
}
private void GeneratePlane(LODTopologyOptions lod, Vector3[] vertices, Vector3[] normals, Vector2[] uv,
Vector4[] tangents, int[] triangles, int planeIndex, float planeRotation)
{
int vertexStartIndex = (lod.verticesX + 1) * (lod.verticesY + 1) * planeIndex;
for (int i = vertexStartIndex, y = 0; y <= lod.verticesY; y++)
{
for (int x = 0; x <= lod.verticesX; x++, i++)
{
float xRatio = (float)x / lod.verticesX;
float yRatio = (float)y / lod.verticesY;
float horizontalCornerCoord = patchSize.x * (xRatio - 0.5f);
float vertexX = horizontalCornerCoord * Mathf.Sin(planeRotation);
float vertexY = patchSize.y * yRatio;
float vertexZ = horizontalCornerCoord * Mathf.Cos(planeRotation);
vertices[i] = new Vector3(vertexX, vertexY, vertexZ);
uv[i] = new Vector2(xRatio, yRatio);
normals[i] = Vector3.up;
tangents[i] = new Vector4(1f, 0f, 0f, -1f);
}
}
int triangleStartIndex = lod.verticesX * lod.verticesY * 6 * planeIndex;
for (int ti = triangleStartIndex, vi = vertexStartIndex, y = 0; y < lod.verticesY; y++, vi++)
{
for (int x = 0; x < lod.verticesX; x++, ti += 6, vi++)
{
triangles[ti] = vi;
triangles[ti + 3] = triangles[ti + 2] = vi + 1;
triangles[ti + 4] = triangles[ti + 1] = vi + lod.verticesX + 1;
triangles[ti + 5] = vi + lod.verticesX + 2;
}
}
}