computeFramingTransform static method

Matrix4 computeFramingTransform(Aabb3 bounds, CameraProjection projection, { double paddingFactor = 1.25, Vector3? viewDirection, Vector3? upVector, })

Computes a camera node world transform that frames bounds with paddingFactor.

The camera looks toward the bounds center from viewDirection (offset from center toward the eye, defaulting to (0, 0, -1) to match glTF front-facing orientation). The resulting matrix is oriented with +Z facing the target, matching NodeCamera.

Implementation

static vm.Matrix4 computeFramingTransform(
  vm.Aabb3 bounds,
  CameraProjection projection, {
  double paddingFactor = 1.25,
  vm.Vector3? viewDirection,
  vm.Vector3? upVector,
}) {
  final center = bounds.center;
  final extents = (bounds.max - bounds.min) * 0.5;
  final radius = math.max(0.1, extents.length);

  final dir = (viewDirection ?? vm.Vector3(0.0, 0.0, -1.0)).normalized();
  var up = upVector ?? vm.Vector3(0.0, 1.0, 0.0);

  // Solve distance from projection FOV
  double distance;
  if (projection is PerspectiveProjection) {
    final halfFov = projection.fovRadiansY * 0.5;
    distance = (radius / math.sin(halfFov)) * paddingFactor;
  } else {
    distance = radius * 2.0 * paddingFactor;
  }

  final eye = center + dir * distance;
  final forward = (center - eye).normalized();
  if (up.cross(forward).length2 < 1e-6) {
    up = vm.Vector3(0, 0, 1);
  }
  final right = up.cross(forward).normalized();
  final actualUp = forward.cross(right).normalized();

  return vm.Matrix4.columns(
    vm.Vector4(right.x, right.y, right.z, 0.0),
    vm.Vector4(actualUp.x, actualUp.y, actualUp.z, 0.0),
    vm.Vector4(forward.x, forward.y, forward.z, 0.0),
    vm.Vector4(eye.x, eye.y, eye.z, 1.0),
  );
}