/// <summary>
/// Adds the circle.
/// </summary>
/// <param name="position">The position.</param>
/// <param name="normal">The normal.</param>
/// <param name="radius">The radius.</param>
/// <param name="segments">The segments.</param>
public void AddCircle(Vector3 position, Vector3 normal, float radius, int segments)
{
if (segments < 3)
{
throw new ArgumentNullException("too few segments, at least 3");
}
normal.Normalize();
float sectionAngle = (float)(2.0 * Math.PI / segments);
var start = new Vector3(radius, 0.0f, 0.0f);
var current = new Vector3(radius, 0.0f, 0.0f);
var next = new Vector3(0.0f, 0.0f, 0.0f);
int posStart = positions.Count;
positions.Add(current);
int currIndex = posStart;
for (int i = 1; i < segments; i++)
{
next.X = radius * (float)Math.Cos(i * sectionAngle);
next.Z = radius * (float)Math.Sin(i * sectionAngle);
current = next;
positions.Add(current);
lineListIndices.Add(currIndex);
lineListIndices.Add(++currIndex);
}
lineListIndices.Add(currIndex);
lineListIndices.Add(posStart);
var axis = Vector3.Cross(Vector3.UnitY, normal);
var transform = Matrix.Translation(position);
if (axis.LengthSquared() > 1e-6)
{
axis.Normalize();
transform = Matrix.RotationAxis(axis, (float)Math.Acos(Vector3.Dot(Vector3.UnitY, normal))) * transform;
}
for (int i = posStart; i < positions.Count; ++i)
{
positions[i] = Vector3.TransformCoordinate(positions[i], transform);
}
}
public static global::SharpDX.Vector3 Normalized(this global::SharpDX.Vector3 vector)
{
vector.Normalize();
return(vector);
}