code: public void setTextureCapturer(GVRTextureCapturer capturer) {
          if (capturer != null) {
              NativeRenderData.setTextureCapturer(getNative(), capturer.getNative());
          } else {
              NativeRenderData.setTextureCapturer(getNative(), 0);
          }
      }
docs: Set the capturer for this texture. If capturer is null, the existing capturer
  is removed. Whether the capturer takes effect depends on the shader associated
  with {@code GVRMaterial}. In order to support the texture capturer, a native
  shader should check {@code RenderData::get_texture_capturer}. See {@code
  ExternalRendererShader} as an example.
  
  @param capturer The capturer.