Function createPickTexture

packages/engine/Source/Scene/BatchTexture.js:452–485

(batchTexture, context)

}

function createPickTexture(batchTexture, context) {
  const featuresLength = batchTexture._featuresLength;
  if (!defined(batchTexture._pickTexture) && featuresLength > 0) {
    const pickIds = batchTexture._pickIds;
    const byteLength = getByteLength(batchTexture);
    const bytes = new Uint8Array(byteLength);
    const owner = batchTexture._owner;
    const statistics = batchTexture._statistics;

    // PERFORMANCE_IDEA: we could skip the pick texture completely by allocating
    // a continuous range of pickIds and then converting the base pickId + batchId
    // to RGBA in the shader.  The only consider is precision issues, which might
    // not be an issue in WebGL 2.
    for (let i = 0; i < featuresLength; ++i) {
      const pickId = context.createPickId(owner.getFeature(i));
      pickIds.push(pickId);

      const pickColor = pickId.color;
      const offset = i * 4;
      bytes[offset] = Color.floatToByte(pickColor.red);
      bytes[offset + 1] = Color.floatToByte(pickColor.green);
      bytes[offset + 2] = Color.floatToByte(pickColor.blue);
      bytes[offset + 3] = Color.floatToByte(pickColor.alpha);
    }

    batchTexture._pickTexture = createTexture(batchTexture, context, bytes);

    // Make sure the tileset statistics are updated the frame when the pick
    // texture is created.
    if (defined(statistics)) {
      statistics.batchTableByteLength += batchTexture._pickTexture.sizeInBytes;
    }
  }
}

function updateBatchTexture(batchTexture) {
  const dimensions = batchTexture._textureDimensions;