runTransformFeedback()

in showcases/wind/src/layers/particle-layer/particle-layer.js [198:269]
59 lines of code
4 McCabe index (conditional complexity)

  runTransformFeedback({gl}) {
    // Run transform feedback
    const {textureFrom, textureTo, delta, timeInterval, transform} = this.state;

    const {bbox} = this.props;

    const {dataBounds, textureArray, textureSize} = this.props.texData;
    const {width, height} = textureSize;

    const {bufferFrom, bufferTo, now} = this.state;
    let {counter} = this.state;

    // onBeforeRender
    const time = Date.now() - now;
    let flip = time > 500 ? 1 : -1;
    if (flip > 0) {
      counter = (counter + 1) % 10;
      flip = counter;
    }

    const pixelStoreParameters = {
      [GL.UNPACK_FLIP_Y_WEBGL]: true
    };

    textureFrom.setImageData({
      pixels: textureArray[timeInterval],
      width,
      height,
      format: gl.RGBA32F,
      type: gl.FLOAT,
      dataFormat: gl.RGBA,
      parameters: pixelStoreParameters
    });

    textureTo.setImageData({
      pixels: textureArray[timeInterval + 1],
      width,
      height,
      format: gl.RGBA32F,
      type: gl.FLOAT,
      dataFormat: gl.RGBA,
      parameters: pixelStoreParameters
    });

    const uniforms = {
      bbox: [bbox.minLng, bbox.maxLng, bbox.minLat, bbox.maxLat],
      bounds0: [dataBounds[0].min, dataBounds[0].max],
      bounds1: [dataBounds[1].min, dataBounds[1].max],
      bounds2: [dataBounds[2].min, dataBounds[2].max],
      dataFrom: textureFrom,
      dataTo: textureTo,
      time,
      flip,
      delta // TODO: looks to be 0 always , verify.
    };

    bufferFrom.setAccessor(Object.assign({}, bufferFrom.accessor, {divisor: 0}));
    bufferTo.setAccessor(Object.assign({}, bufferTo.accessor, {divisor: 0}));

    transform.run({uniforms});
    transform.swapBuffers();

    if (flip > 0) {
      flip = -1;
      this.setState({
        now: Date.now()
      });
    }
    this.setState({
      counter
    });
  }