/// <summary>
/// Creates a circular shadow hull
/// </summary>
/// <param name="radius">radius of the circle</param>
/// <param name="sides">number of sides the circle will be comprised of</param>
/// <returns>A circular shadow hull</returns>
public static ShadowHull CreateCircle(float radius, int sides)
{
// Validate input
if (sides < 3)
{
throw new ArgumentException("Shadow hull must have at least 3 sides.");
}
ShadowHull hull = new ShadowHull();
hull.MaxRadius = radius;
// Calculate number of sides
hull.NumPoints = sides * 2;
var numTris = hull.NumPoints - 2;
hull.NumIndicies = numTris * 3;
hull.Points = new ShadowHullPoint[hull.NumPoints];
hull.Indicies = new Int32[hull.NumIndicies];
var angle = (float)(-Math.PI * 2) / sides; // XNA Renders Clockwise
var angleOffset = angle / 2;
for (int i = 0; i < sides; i++)
{
// Create vertices
var v1 = new ShadowHullPoint();
var v2 = new ShadowHullPoint();
// Vertex Position
v1.Position.X = (float)Math.Cos(angle * i) * radius;
v1.Position.Y = (float)Math.Sin(angle * i) * radius;
v2.Position.X = (float)Math.Cos(angle * (i + 1)) * radius;
v2.Position.Y = (float)Math.Sin(angle * (i + 1)) * radius;
// Vertex Normal
v1.Normal.X = (float)Math.Cos(angle * i + angleOffset);
v1.Normal.Y = (float)Math.Sin(angle * i + angleOffset);
v2.Normal.X = (float)Math.Cos(angle * i + angleOffset);
v2.Normal.Y = (float)Math.Sin(angle * i + angleOffset);
// Copy vertices
hull.Points[i * 2 + 0] = v1;
hull.Points[i * 2 + 1] = v2;
}
for (int i = 0; i < numTris; i++)
{
hull.Indicies[i * 3 + 0] = 0;
hull.Indicies[i * 3 + 1] = (Int16)(i + 1);
hull.Indicies[i * 3 + 2] = (Int16)(i + 2);
}
return(hull);
}
/// <summary> Creates a circular shadow hull </summary>
/// <param name="radius">radius of the circle</param>
/// <param name="sides">number of sides the circle will be comprised of</param>
/// <returns>A circular shadow hull</returns>
public static ShadowHull CreateCircle(float radius, int sides)
{
// Validate input
if (sides < 3) { throw new ArgumentException("Shadow hull must have at least 3 sides."); }
var hull = new ShadowHull { MaxRadius = radius, NumPoints = sides * 2 };
// Calculate number of sides
var numTris = hull.NumPoints - 2;
hull.NumIndicies = numTris * 3;
hull.Points = new ShadowHullPoint[hull.NumPoints];
hull.Indicies = new Int32[hull.NumIndicies];
var angle = (float)(-Math.PI * 2) / sides; // XNA Renders Clockwise
var angleOffset = angle / 2;
for (int i = 0; i < sides; i++) {
// Create vertices
var v1 = new ShadowHullPoint();
var v2 = new ShadowHullPoint();
// Vertex Position
v1.Position.X = (float)Math.Cos(angle * i) * radius;
v1.Position.Y = (float)Math.Sin(angle * i) * radius;
v2.Position.X = (float)Math.Cos(angle * (i + 1)) * radius;
v2.Position.Y = (float)Math.Sin(angle * (i + 1)) * radius;
// Vertex Normal
v1.Normal.X = (float)Math.Cos(angle * i + angleOffset);
v1.Normal.Y = (float)Math.Sin(angle * i + angleOffset);
v2.Normal.X = (float)Math.Cos(angle * i + angleOffset);
v2.Normal.Y = (float)Math.Sin(angle * i + angleOffset);
// Copy vertices
hull.Points[i * 2 + 0] = v1;
hull.Points[i * 2 + 1] = v2;
}
for (int i = 0; i < numTris; i++) {
hull.Indicies[i * 3 + 0] = 0;
hull.Indicies[i * 3 + 1] = i + 1;
hull.Indicies[i * 3 + 2] = i + 2;
}
return hull;
}
