Function execute2DViewportCommands

packages/engine/Source/Scene/Scene.js:3322–3483

* Execute the draw commands to render into a 2D viewport. * * @param {Scene} scene * @param {PassState} passState * * @private

(scene, passState)

 * @private
 */
function execute2DViewportCommands(scene, passState) {
  const { frameState, camera } = scene;
  const { uniformState } = scene.context;

  const originalViewport = passState.viewport;
  const viewport = BoundingRectangle.clone(originalViewport, scratch2DViewport);
  passState.viewport = viewport;

  const maxCartographic = scratch2DViewportCartographic;
  const maxCoord = scratch2DViewportMaxCoord;

  const projection = scene.mapProjection;
  projection.project(maxCartographic, maxCoord);

  const position = Cartesian3.clone(
    camera.position,
    scratch2DViewportSavedPosition,
  );
  const transform = Matrix4.clone(
    camera.transform,
    scratch2DViewportCameraTransform,
  );
  const frustum = camera.frustum.clone();

  camera._setTransform(Matrix4.IDENTITY);

  const viewportTransformation = Matrix4.computeViewportTransformation(
    viewport,
    0.0,
    1.0,
    scratch2DViewportTransform,
  );
  const projectionMatrix = camera.frustum.projectionMatrix;

  const x = camera.positionWC.y;
  const eyePoint = Cartesian3.fromElements(
    CesiumMath.sign(x) * maxCoord.x - x,
    0.0,
    -camera.positionWC.x,
    scratch2DViewportEyePoint,
  );
  const windowCoordinates = Transforms.pointToGLWindowCoordinates(
    projectionMatrix,
    viewportTransformation,
    eyePoint,
    scratch2DViewportWindowCoords,
  );

  windowCoordinates.x = Math.floor(windowCoordinates.x);

  const viewportX = viewport.x;
  const viewportWidth = viewport.width;

  if (
    x === 0.0 ||
    windowCoordinates.x <= viewportX ||
    windowCoordinates.x >= viewportX + viewportWidth
  ) {