Function look3D

packages/engine/Source/Scene/ScreenSpaceCameraController.js:2750–2872

(controller, startPosition, movement, rotationAxis)

const look3DTan = new Cartesian3();

function look3D(controller, startPosition, movement, rotationAxis) {
  const scene = controller._scene;
  const camera = scene.camera;

  const startPos = look3DStartPos;
  startPos.x = movement.startPosition.x;
  startPos.y = 0.0;
  const endPos = look3DEndPos;
  endPos.x = movement.endPosition.x;
  endPos.y = 0.0;

  let startRay = camera.getPickRay(startPos, look3DStartRay);
  let endRay = camera.getPickRay(endPos, look3DEndRay);
  let angle = 0.0;
  let start;
  let end;

  if (camera.frustum instanceof OrthographicFrustum) {
    start = startRay.origin;
    end = endRay.origin;

    Cartesian3.add(camera.direction, start, start);
    Cartesian3.add(camera.direction, end, end);

    Cartesian3.subtract(start, camera.position, start);
    Cartesian3.subtract(end, camera.position, end);

    Cartesian3.normalize(start, start);
    Cartesian3.normalize(end, end);
  } else {
    start = startRay.direction;
    end = endRay.direction;
  }

  let dot = Cartesian3.dot(start, end);
  if (dot < 1.0) {
    // dot is in [0, 1]
    angle = Math.acos(dot);
  }

  angle = movement.startPosition.x > movement.endPosition.x ? -angle : angle;

  const horizontalRotationAxis = controller._horizontalRotationAxis;
  if (defined(rotationAxis)) {
    camera.look(rotationAxis, -angle);
  } else if (defined(horizontalRotationAxis)) {
    camera.look(horizontalRotationAxis, -angle);
  } else {
    camera.lookLeft(angle);
  }

  startPos.x = 0.0;
  startPos.y = movement.startPosition.y;
  endPos.x = 0.0;
  endPos.y = movement.endPosition.y;

  startRay = camera.getPickRay(startPos, look3DStartRay);
  endRay = camera.getPickRay(endPos, look3DEndRay);