PerspectiveCamera.framing constructor

PerspectiveCamera.framing(Aabb3 bounds, { Vector3? direction, double fovRadiansY = 45 * degrees2Radians, Vector3? up, double margin = 1.1, })

Places a camera to frame bounds (a model's world-space AABB, from Node.combinedWorldBounds) so it fills the view.

The camera looks at the bounds' center from direction (the offset from the center toward the eye; defaults to (0, 0, -1), matching the default placement and the direction glTF models face after import). The distance fits the bounds' bounding sphere within the vertical field of view, so it frames cleanly on a landscape view; margin above 1 pulls the camera back for padding (a portrait view, whose horizontal field of view is narrower, may want some). The near and far planes are set around the model so a tiny or a huge one both stay in range.

Implementation

factory PerspectiveCamera.framing(
  Aabb3 bounds, {
  Vector3? direction,
  double fovRadiansY = 45 * degrees2Radians,
  Vector3? up,
  double margin = 1.1,
}) {
  final center = bounds.center;
  final radius = max((bounds.max - bounds.min).length * 0.5, 1e-4);
  final distance = radius / sin(fovRadiansY / 2) * margin;
  final dir = (direction ?? Vector3(0, 0, -1)).normalized();
  return PerspectiveCamera(
    fovRadiansY: fovRadiansY,
    position: center + dir * distance,
    target: center,
    up: up,
    fovNear: max(distance - radius, distance * 1e-3),
    fovFar: distance + radius * 2,
  );
}