public ContainmentType Contains(AxisAlignedBox3D box)
{
// FIXME: Is this a bug?
// If the bounding box is of W * D * H = 0, then return disjoint
if (box.Min == box.Max)
{
return(ContainmentType.Disjoint);
}
int i;
ContainmentType contained;
Point3D[] corners = box.GetCorners();
// First we assume completely disjoint. So if we find a point that is contained, we break out of this loop
for (i = 0; i < corners.Length; i++)
{
if (Contains(corners[i]) != ContainmentType.Disjoint)
{
break;
}
}
if (i == corners.Length) // This means we checked all the corners and they were all disjoint
{
return(ContainmentType.Disjoint);
}
if (i != 0) // if i is not equal to zero, we can fastpath and say that this box intersects
{ // because we know at least one point is outside and one is inside.
return(ContainmentType.Intersects);
}
// If we get here, it means the first (and only) point we checked was actually contained in the frustum.
// So we assume that all other points will also be contained. If one of the points is disjoint, we can
// exit immediately saying that the result is Intersects
i++;
for (; i < corners.Length; i++)
{
if (Contains(corners[i]) != ContainmentType.Contains)
{
return(ContainmentType.Intersects);
}
}
// If we get here, then we know all the points were actually contained, therefore result is Contains
return(ContainmentType.Contains);
}
public static PerspectiveCamera CreateFromBounds(AxisAlignedBox3D bounds, Viewport3D viewport,
float fieldOfView, float yaw = 0.0f, float pitch = 0.0f, float zoom = 1.0f)
{
// Calculate initial guess at camera settings.
Matrix3D transform = Matrix3D.CreateFromYawPitchRoll(yaw, pitch, 0);
Vector3D cameraDirection = Vector3D.Normalize(transform.Transform(Vector3D.Forward));
PerspectiveCamera initialGuess = new PerspectiveCamera
{
FieldOfView = fieldOfView,
NearPlaneDistance = 1.0f,
FarPlaneDistance = bounds.Size.Length() * 10,
Position = bounds.Center - cameraDirection * bounds.Size.Length() * 2,
LookDirection = cameraDirection,
UpDirection = Vector3D.Up
};
Matrix3D projection = initialGuess.GetProjectionMatrix(viewport.AspectRatio);
Matrix3D view = initialGuess.GetViewMatrix();
// Project bounding box corners onto screen, and calculate screen bounds.
float closestZ = float.MaxValue;
Box2D? screenBounds = null;
Point3D[] corners = bounds.GetCorners();
foreach (Point3D corner in corners)
{
Point3D screenPoint = viewport.Project(corner,
projection, view, Matrix3D.Identity);
if (screenPoint.Z < closestZ)
closestZ = screenPoint.Z;
IntPoint2D intScreenPoint = new IntPoint2D((int) screenPoint.X, (int) screenPoint.Y);
if (screenBounds == null)
screenBounds = new Box2D(intScreenPoint, intScreenPoint);
else
{
Box2D value = screenBounds.Value;
value.Expand(intScreenPoint);
screenBounds = value;
}
}
// Now project back from screen bounds into scene, setting Z to the minimum bounding box Z value.
IntPoint2D minScreen = screenBounds.Value.Min;
IntPoint2D maxScreen = screenBounds.Value.Max;
Point3D min = viewport.Unproject(new Point3D(minScreen.X, minScreen.Y, closestZ),
projection, view, Matrix3D.Identity);
Point3D max = viewport.Unproject(new Point3D(maxScreen.X, maxScreen.Y, closestZ),
projection, view, Matrix3D.Identity);
// Use these new values to calculate the distance the camera should be from the AABB centre.
Vector3D size = Vector3D.Abs(max - min);
float radius = size.Length();
float dist = radius / (2 * MathUtility.Tan(fieldOfView * viewport.AspectRatio / 2));
Point3D closestBoundsCenter = (min + (max - min) / 2);
Point3D position = closestBoundsCenter - cameraDirection * dist * (1 / zoom);
return new PerspectiveCamera
{
FieldOfView = fieldOfView,
NearPlaneDistance = 1.0f,
FarPlaneDistance = dist * 10,
Position = position,
LookDirection = cameraDirection,
UpDirection = Vector3D.Up
};
}
