Issue/24 (#549)

* Implemented property animation mechanism
 * Added easing functions to Ghoul and make them usable in animation
 * Make sure that we don't leave properties around if SceneGraphNodes are deleted
 * Adding opacity settings to base renderables

modules/base/rendering/renderableplane.cpp

@@ -111,6 +111,9 @@ RenderablePlane::RenderablePlane(const ghoul::Dictionary& dictionary)
         "RenderablePlane"
     );
 
+    addProperty(_opacity);
+    registerUpdateRenderBinFromOpacity();
+
     _size = static_cast<float>(dictionary.value<double>(SizeInfo.identifier));
 
     if (dictionary.hasKey(BillboardInfo.identifier)) {
@@ -185,6 +188,8 @@ void RenderablePlane::deinitializeGL() {
 void RenderablePlane::render(const RenderData& data, RendererTasks&) {
     _shader->activate();
 
+    _shader->setUniform("opacity", _opacity);
+
     // Model transform and view transform needs to be in double precision
     const glm::dmat4 rotationTransform = _billboard ?
         glm::inverse(glm::dmat4(data.camera.viewRotationMatrix())) :