private void RenderLine(Vector3 start, Vector3 end, Plane plane, Color color, ICamera camera, I2DRenderer im)
{
var line = new Line(start, end);
var cls = line.ClassifyAgainstPlane(plane);
if (cls == PlaneClassification.Back)
{
return;
}
if (cls == PlaneClassification.Spanning)
{
var isect = plane.GetIntersectionPoint(line, true);
var first = plane.OnPlane(line.Start) > 0 ? line.Start : line.End;
if (!isect.HasValue)
{
return;
}
line = new Line(first, isect.Value);
}
var st = camera.WorldToScreen(line.Start);
var en = camera.WorldToScreen(line.End);
im.AddLine(st.ToVector2(), en.ToVector2(), color, 2);
}
/// <summary>
/// Determines if this line is behind, in front, or spanning a plane.
/// </summary>
/// <param name="p">The plane to test against</param>
/// <returns>A PlaneClassification value.</returns>
public PlaneClassification ClassifyAgainstPlane(Plane p)
{
var start = p.OnPlane(Start);
var end = p.OnPlane(End);
if (start == 0 && end == 0)
{
return(PlaneClassification.OnPlane);
}
if (start <= 0 && end <= 0)
{
return(PlaneClassification.Back);
}
if (start >= 0 && end >= 0)
{
return(PlaneClassification.Front);
}
return(PlaneClassification.Spanning);
}
private void AddLine(CircleType type, Vector3 start, Vector3 end, Plane test, CachedLines cache)
{
var line = new Line(start, end);
var cls = line.ClassifyAgainstPlane(test);
if (cls == PlaneClassification.Back)
{
return;
}
if (cls == PlaneClassification.Spanning)
{
var isect = test.GetIntersectionPoint(line, true);
var first = test.OnPlane(line.Start) > 0 ? line.Start : line.End;
if (isect.HasValue)
{
line = new Line(first, isect.Value);
}
}
cache.Cache[type].Add(new Line(cache.Viewport.Camera.WorldToScreen(line.Start), cache.Viewport.Camera.WorldToScreen(line.End)));
}
/// <summary>
/// Determines if this polygon is behind, in front, or spanning a plane.
/// </summary>
/// <param name="p">The plane to test against</param>
/// <returns>A PlaneClassification value.</returns>
public PlaneClassification ClassifyAgainstPlane(Plane p)
{
var count = Vertices.Count;
var front = 0;
var back = 0;
var onplane = 0;
foreach (var t in Vertices)
{
var test = p.OnPlane(t);
// Vertices on the plane are both in front and behind the plane in this context
if (test <= 0)
{
back++;
}
if (test >= 0)
{
front++;
}
if (test == 0)
{
onplane++;
}
}
if (onplane == count)
{
return(PlaneClassification.OnPlane);
}
if (front == count)
{
return(PlaneClassification.Front);
}
if (back == count)
{
return(PlaneClassification.Back);
}
return(PlaneClassification.Spanning);
}