public CircleGeometry(float radius = 1, int segments = 8, float thetaStart = 0, float thetaLength = Mathf.Tau)
{
segments = Mathf.Max(3, segments);
var uvs = new List <Vector2>();
vertices.Add(Vector3.Zero);
uvs.Add(Vector2.Half);
for (var i = 0f; i <= segments; i++)
{
var segment = thetaStart + i / segments * thetaLength;
var v = new Vector3(Mathf.Cos(segment), radius * Mathf.Sin(segment), 0);
v.Multiply(radius);
vertices.Add(v);
uvs.Add(new Vector2((v.x / radius + 1) / 2, (v.y / radius + 1) / 2));
}
var n = Vector3.UnitZ;
for (var i = 1; i <= segments; i++)
{
faces.Add(new Face3(i, i + 1, 0, n));
var faceSet = new UVFaceSet(uvs[i], uvs[i + 1], Vector2.Half);
faceVertexUvs[0].Add(faceSet);
}
ComputeNormals();
BoundingSphere = new Sphere(Vector3.Zero, radius);
}
// Approximate a curved face with recursively sub-divided triangles.
private void Make(VertexInfo v1, VertexInfo v2, VertexInfo v3)
{
var face = new Face3(v1.Index, v2.Index, v3.Index, v1.Position, v2.Position, v3.Position);
faces.Add(face);
var centroid = v1.Position;
centroid.Add(v2.Position);
centroid.Add(v3.Position);
centroid.Divide(3);
var azi = Azimuth(centroid);
var uvA = CorrectUV(v1.UV, v1.Position, azi);
var uvB = CorrectUV(v2.UV, v2.Position, azi);
var uvC = CorrectUV(v3.UV, v3.Position, azi);
var faceSet = new UVFaceSet(uvA, uvB, uvC);
var uvs = faceVertexUvs[0];
uvs.Add(faceSet);
}
