/// <summary>
/// Creates a cube with six faces each one pointing in a different direction.
/// </summary>
/// <param name="size">The size.</param>
/// <param name="toLeftHanded">if set to <c>true</c> vertices and indices will be transformed to left handed. Default is false.</param>
/// <returns>A cube.</returns>
public static GeometricMeshData <VertexPositionNormalTangentMultiTexture> New(float size = 1.0f, bool toLeftHanded = false)
{
var vertices = new VertexPositionNormalTangentMultiTexture[CubeFaceCount * 4];
var indices = new int[CubeFaceCount * 6];
size /= 2.0f;
int vertexCount = 0;
int indexCount = 0;
// Create each face in turn.
for (int i = 0; i < CubeFaceCount; i++)
{
Vector3 normal = faceNormals[i];
// Get two vectors perpendicular both to the face normal and to each other.
Vector3 basis = (i >= 4) ? Vector3.UnitZ : Vector3.UnitY;
Vector3 side1;
Vector3.Cross(ref normal, ref basis, out side1);
Vector3 side2;
Vector3.Cross(ref normal, ref side1, out side2);
// Six indices (two triangles) per face.
int vbase = i * 4;
indices[indexCount++] = (vbase + 0);
indices[indexCount++] = (vbase + 1);
indices[indexCount++] = (vbase + 2);
indices[indexCount++] = (vbase + 0);
indices[indexCount++] = (vbase + 2);
indices[indexCount++] = (vbase + 3);
// Four vertices per face.
vertices[vertexCount++] = new VertexPositionNormalTangentMultiTexture((normal - side1 - side2) * size, normal, new Vector4(-side1, 0), textureCoordinates[0]);
vertices[vertexCount++] = new VertexPositionNormalTangentMultiTexture((normal - side1 + side2) * size, normal, new Vector4(-side1, 0), textureCoordinates[1]);
vertices[vertexCount++] = new VertexPositionNormalTangentMultiTexture((normal + side1 + side2) * size, normal, new Vector4(-side1, 0), textureCoordinates[2]);
vertices[vertexCount++] = new VertexPositionNormalTangentMultiTexture((normal + side1 - side2) * size, normal, new Vector4(-side1, 0), textureCoordinates[3]);
}
// Create the primitive object.
return(new GeometricMeshData <VertexPositionNormalTangentMultiTexture>(vertices, indices, toLeftHanded)
{
Name = "Cube"
});
}
/// <summary>
/// Creates a sphere primitive.
/// </summary>
/// <param name="diameter">The diameter.</param>
/// <param name="tessellation">The tessellation.</param>
/// <param name="toLeftHanded">if set to <c>true</c> vertices and indices will be transformed to left handed. Default is false.</param>
/// <returns>A sphere primitive.</returns>
/// <exception cref="System.ArgumentOutOfRangeException">tessellation;Must be >= 3</exception>
public static GeometricMeshData <VertexPositionNormalTangentMultiTexture> New(float diameter = 1.0f, int tessellation = 16, bool toLeftHanded = false)
{
if (tessellation < 3)
{
throw new ArgumentOutOfRangeException("tessellation", "Must be >= 3");
}
int verticalSegments = tessellation;
int horizontalSegments = tessellation * 2;
var vertices = new VertexPositionNormalTangentMultiTexture[(verticalSegments + 1) * (horizontalSegments + 1)];
var indices = new int[(verticalSegments) * (horizontalSegments + 1) * 6];
float radius = diameter / 2;
int vertexCount = 0;
// Create rings of vertices at progressively higher latitudes.
for (int i = 0; i <= verticalSegments; i++)
{
float v = 1.0f - (float)i / verticalSegments;
var latitude = (float)((i * Math.PI / verticalSegments) - Math.PI / 2.0);
var dy = (float)Math.Sin(latitude);
var dxz = (float)Math.Cos(latitude);
// Create a single ring of vertices at this latitude.
for (int j = 0; j <= horizontalSegments; j++)
{
float u = (float)j / horizontalSegments;
var longitude = (float)(j * 2.0 * Math.PI / horizontalSegments);
var dx = (float)Math.Sin(longitude);
var dz = (float)Math.Cos(longitude);
dx *= dxz;
dz *= dxz;
var normal = new Vector3(dx, dy, dz);
var textureCoordinate = new Vector2(u, v);
var tangent = new Vector4(normal.Z, 0, -normal.X, 0); // Y ^ normal
vertices[vertexCount++] = new VertexPositionNormalTangentMultiTexture(normal * radius, normal, tangent, textureCoordinate);
}
}
// Fill the index buffer with triangles joining each pair of latitude rings.
int stride = horizontalSegments + 1;
int indexCount = 0;
for (int i = 0; i < verticalSegments; i++)
{
for (int j = 0; j <= horizontalSegments; j++)
{
int nextI = i + 1;
int nextJ = (j + 1) % stride;
indices[indexCount++] = (i * stride + j);
indices[indexCount++] = (nextI * stride + j);
indices[indexCount++] = (i * stride + nextJ);
indices[indexCount++] = (i * stride + nextJ);
indices[indexCount++] = (nextI * stride + j);
indices[indexCount++] = (nextI * stride + nextJ);
}
}
// Create the primitive object.
// Create the primitive object.
return(new GeometricMeshData <VertexPositionNormalTangentMultiTexture>(vertices, indices, toLeftHanded)
{
Name = "Sphere"
});
}
