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
});
}
