Function updateSunPosition

packages/engine/Source/Scene/SunPostProcess.js:145–229

(postProcess, context, viewport)

const postProcessMatrix4Scratch = new Matrix4();

function updateSunPosition(postProcess, context, viewport) {
  const us = context.uniformState;
  const sunPosition = us.sunPositionWC;
  const viewMatrix = us.view;
  const viewProjectionMatrix = us.viewProjection;
  const projectionMatrix = us.projection;

  // create up sampled render state
  let viewportTransformation = Matrix4.computeViewportTransformation(
    viewport,
    0.0,
    1.0,
    postProcessMatrix4Scratch,
  );
  const sunPositionEC = Matrix4.multiplyByPoint(
    viewMatrix,
    sunPosition,
    sunPositionECScratch,
  );
  let sunPositionWC = Transforms.pointToGLWindowCoordinates(
    viewProjectionMatrix,
    viewportTransformation,
    sunPosition,
    sunPositionWCScratch,
  );

  sunPositionEC.x += CesiumMath.SOLAR_RADIUS;
  const limbWC = Transforms.pointToGLWindowCoordinates(
    projectionMatrix,
    viewportTransformation,
    sunPositionEC,
    sunPositionEC,
  );
  const sunSize =
    Cartesian2.magnitude(Cartesian2.subtract(limbWC, sunPositionWC, limbWC)) *
    30.0 *
    2.0;

  const size = sizeScratch;
  size.x = sunSize;
  size.y = sunSize;

  postProcess._uCenter = Cartesian2.clone(sunPositionWC, postProcess._uCenter);
  postProcess._uRadius = Math.max(size.x, size.y) * 0.15;

  const width = context.drawingBufferWidth;
  const height = context.drawingBufferHeight;

  const stages = postProcess._stages;
  const firstStage = stages.get(0);

  const downSampleWidth = firstStage.outputTexture.width;
  const downSampleHeight = firstStage.outputTexture.height;

  const downSampleViewport = new BoundingRectangle();
  downSampleViewport.width = downSampleWidth;
  downSampleViewport.height = downSampleHeight;