bindInitialFrameBuffer() {
    const gl = this.getGL();
    const frameBuffer = this.postProcessPasses_[0].getFrameBuffer();
    gl.bindFramebuffer(gl.FRAMEBUFFER, frameBuffer);
    const texture = this.postProcessPasses_[0].getRenderTargetTexture();
    gl.framebufferTexture2D(
      gl.FRAMEBUFFER,
      gl.COLOR_ATTACHMENT0,
      gl.TEXTURE_2D,
      texture,
      0,
    );
  }
Bind the frame buffer from the initial render.