| public static AngleFromXY ( float x, float y ) : float | ||
| x | float | |
| y | float | |
| return | float | |
public static MeshData CreateGeosphere(float radius, SubdivisionCount numSubdivisions)
{
var tempMesh = new MeshData {
Vertices = IcosahedronVertices.Select(p => new Vertex {
Position = p
}).ToList(),
Indices = IcosahedronIndices
};
var mh = new Subdivider();
for (var i = 0; i < (int)numSubdivisions; i++)
{
mh.Subdivide4(tempMesh);
}
// Project vertices onto sphere and scale.
for (var i = 0; i < tempMesh.Vertices.Count; i++)
{
// Project onto unit sphere.
var n = Vector3.Normalize(tempMesh.Vertices[i].Position);
// Project onto sphere.
var p = radius * n;
// Derive texture coordinates from spherical coordinates.
var theta = MathF.AngleFromXY(tempMesh.Vertices[i].Position.X, tempMesh.Vertices[i].Position.Z);
var phi = MathUtils.Acos(tempMesh.Vertices[i].Position.Y / radius);
var texC = new Vector2(theta / (2 * MathF.PI), phi / MathF.PI);
// Partial derivative of P with respect to theta
var tangent = new Vector3(
-radius * MathUtils.Sin(phi) * MathUtils.Sin(theta),
0,
radius * MathUtils.Sin(phi) * MathUtils.Cos(theta));
tangent.Normalize();
tempMesh.Vertices[i] = new Vertex(p, n, tangent, texC);
}
return(tempMesh);
}
public static MeshData CreateGeosphere(float radius, SubdivisionCount numSubdivisions)
{
var tempMesh = new MeshBuilder {
VerticesBuffer = IcosahedronVertices.Select(p => new Vertex(p)).ToArray(),
IndicesBuffer = IcosahedronIndices
};
for (var i = 0; i < (int)numSubdivisions; i++)
{
Subdivide4(tempMesh);
}
// Project vertices onto sphere and scale.
for (var i = 0; i < tempMesh.VerticesCount; i++)
{
// Project onto unit sphere.
var n = Vector3.Normalize(tempMesh.VerticesBuffer[i].Position);
// Project onto sphere.
var p = radius * n;
// Derive texture coordinates from spherical coordinates.
var theta = MathF.AngleFromXY(tempMesh.VerticesBuffer[i].Position.X, tempMesh.VerticesBuffer[i].Position.Z);
var phi = (tempMesh.VerticesBuffer[i].Position.Y / radius).Acos();
var texC = new Vector2(theta / (2 * MathF.PI), phi / MathF.PI);
// Partial derivative of P with respect to theta
var tangent = new Vector3(
-radius * phi.Sin() * theta.Sin(),
0,
radius * phi.Sin() * theta.Cos());
tangent.Normalize();
tempMesh.VerticesBuffer[i] = new Vertex(p, n, texC, tangent);
}
return(tempMesh.Seal());
}
