public void PlaneConstructionTest()
{
var p1 = new Coordinate(-100, -100, 100);
var p2 = new Coordinate(100, -100, 100);
var p3 = new Coordinate(100, 100, 100);
var p4 = new Coordinate(0, 0, 0);
var refPlane = new Plane(new Coordinate(0, 0, 1), 100);
var plane = new Plane(p3, p2, p1);
var o1 = refPlane.OnPlane(p1);
var o2 = plane.OnPlane(p1);
var o3 = refPlane.OnPlane(p4);
var o4 = plane.OnPlane(p4);
Assert.IsTrue(o1 == 0);
Assert.IsTrue(o2 == 0);
Assert.IsFalse(o3 == 0);
Assert.IsFalse(o4 == 0);
Assert.AreEqual(refPlane.A, plane.A);
Assert.AreEqual(refPlane.B, plane.B);
Assert.AreEqual(refPlane.C, plane.C);
Assert.AreEqual(refPlane.D, plane.D);
var plane2 = new Plane(new Coordinate(-192, 704, 192),
new Coordinate(-192, 320, 192),
new Coordinate(-192, 320, -192));
}
/// <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;
}
/// <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)
{
int front = 0, back = 0, onplane = 0, count = Vertices.Count;
foreach (var test in Vertices.Select(x => p.OnPlane(x)))
{
// 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);
}
private void RenderLine(Vector3 start, Vector3 end, Plane plane, Color color, ICamera camera, Graphics graphics)
{
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);
using (var p = new Pen(color, 2))
{
graphics.DrawLine(p, st.X, st.Y, en.X, en.Y);
}
}
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);
}
/// <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)
{
int front = 0, back = 0, onplane = 0, count = Vertices.Count;
foreach (var test in Vertices.Select(x => p.OnPlane(x)))
{
// 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;
}
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);
}
/// <summary>
/// Splits this polygon by a clipping plane, returning the back and front planes.
/// The original polygon is not modified.
/// </summary>
/// <param name="clip">The clipping plane</param>
/// <param name="back">The back polygon</param>
/// <param name="front">The front polygon</param>
/// <returns>True if the split was successful</returns>
public bool Split(Plane clip, out Polygon back, out Polygon front)
{
// If the polygon doesn't span the plane, return false.
var classify = ClassifyAgainstPlane(clip);
if (classify != PlaneClassification.Spanning)
{
back = front = null;
if (classify == PlaneClassification.Back) back = this;
else if (classify == PlaneClassification.Front) front = this;
return false;
}
// Get the new front and back vertices
var backVerts = new List<Coordinate>();
var frontVerts = new List<Coordinate>();
var prev = 0;
for (var i = 0; i <= Vertices.Count; i++)
{
var end = Vertices[i % Vertices.Count];
var cls = clip.OnPlane(end);
// Check plane crossing
if (i > 0 && cls != 0 && prev != 0 && prev != cls)
{
// This line end point has crossed the plane
// Add the line intersect to the
var start = Vertices[i - 1];
var line = new Line(start, end);
var isect = clip.GetIntersectionPoint(line, true);
if (isect == null) throw new Exception("Expected intersection, got null.");
frontVerts.Add(isect);
backVerts.Add(isect);
}
// Add original points
if (i < Vertices.Count)
{
// OnPlane points get put in both polygons, doesn't generate split
if (cls >= 0) frontVerts.Add(end);
if (cls <= 0) backVerts.Add(end);
}
prev = cls;
}
back = new Polygon(backVerts);
front = new Polygon(frontVerts);
return true;
}
private void AddLine(CircleType type, Coordinate start, Coordinate 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;
line = new Line(first, isect);
}
cache.Cache[type].Add(new Line(cache.Viewport3D.WorldToScreen(line.Start), cache.Viewport3D.WorldToScreen(line.End)));
}
/// <summary>
/// Splits this polygon by a clipping plane, returning the back and front planes.
/// The original polygon is not modified.
/// </summary>
/// <param name="clip">The clipping plane</param>
/// <param name="back">The back polygon</param>
/// <param name="front">The front polygon</param>
/// <param name="coplanarBack">If the polygon rests on the plane and points backward, this will not be null</param>
/// <param name="coplanarFront">If the polygon rests on the plane and points forward, this will not be null</param>
/// <returns>True if the split was successful</returns>
public bool Split(Plane clip, out Polygon back, out Polygon front, out Polygon coplanarBack, out Polygon coplanarFront)
{
// If the polygon doesn't span the plane, return false.
var classify = ClassifyAgainstPlane(clip);
if (classify != PlaneClassification.Spanning)
{
back = front = null;
coplanarBack = coplanarFront = null;
if (classify == PlaneClassification.Back)
{
back = this;
}
else if (classify == PlaneClassification.Front)
{
front = this;
}
else if (Plane.Normal.Dot(clip.Normal) > 0)
{
coplanarFront = this;
}
else
{
coplanarBack = this;
}
return(false);
}
// Get the new front and back vertices
var backVerts = new List <Coordinate>();
var frontVerts = new List <Coordinate>();
var prev = 0;
for (var i = 0; i <= Vertices.Count; i++)
{
var end = Vertices[i % Vertices.Count];
var cls = clip.OnPlane(end);
// Check plane crossing
if (i > 0 && cls != 0 && prev != 0 && prev != cls)
{
// This line end point has crossed the plane
// Add the line intersect to the
var start = Vertices[i - 1];
var line = new Line(start, end);
var isect = clip.GetIntersectionPoint(line, true);
if (isect == null)
{
throw new Exception("Expected intersection, got null.");
}
frontVerts.Add(isect);
backVerts.Add(isect);
}
// Add original points
if (i < Vertices.Count)
{
// OnPlane points get put in both polygons, doesn't generate split
if (cls >= 0)
{
frontVerts.Add(end);
}
if (cls <= 0)
{
backVerts.Add(end);
}
}
prev = cls;
}
back = new Polygon(backVerts);
front = new Polygon(frontVerts);
coplanarBack = coplanarFront = null;
return(true);
}
