add render bins to improve rendering of transparent objects using framebuffer renderer

include/openspace/rendering/renderable.h

@@ -51,6 +51,13 @@ class PowerScaledCoordinate;
 
 class Renderable : public properties::PropertyOwner {
 public:
+    enum class RenderBin : int {
+        Background = 1,
+        Opaque = 2,
+        Transparent = 4,
+        Overlay = 8
+    };
+
     static Renderable* createFromDictionary(const ghoul::Dictionary& dictionary);
 
     // constructors & destructor
@@ -72,6 +79,10 @@ public:
     virtual void postRender(const RenderData& data);
     virtual void update(const UpdateData& data);
 
+    RenderBin renderBin() const;
+    void setRenderBin(RenderBin bin);
+    bool matchesRenderBinMask(int binMask);
+
     bool isVisible() const;
     
     bool hasTimeInterval();
@@ -89,6 +100,7 @@ protected:
     properties::BoolProperty _enabled;
     
 private:
+    RenderBin _renderBin;
     PowerScaledScalar boundingSphere_;
     std::string _startTime;
     std::string _endTime;

include/openspace/util/updatestructures.h

@@ -43,10 +43,12 @@ struct UpdateData {
     bool doPerformanceMeasurement;
 };
 
+
 struct RenderData {
     const Camera& camera;
     psc position;
     bool doPerformanceMeasurement;
+    int renderBinMask;
 };
 
 struct RaycasterTask {

modules/base/rendering/renderabletrail.cpp

@@ -124,6 +124,7 @@ bool RenderableTrail::initialize() {
         "${MODULE_BASE}/shaders/ephemeris_vs.glsl",
         "${MODULE_BASE}/shaders/ephemeris_fs.glsl");
 
+    setRenderBin(Renderable::RenderBin::Overlay);
 
     if (!_programObject)
         return false;

src/rendering/abufferrenderer.cpp

@@ -28,6 +28,7 @@
 #include <openspace/engine/openspaceengine.h>
 #include <openspace/engine/wrapper/windowwrapper.h>
 #include <openspace/rendering/renderengine.h>
+#include <openspace/rendering/renderable.h>
 #include <openspace/rendering/volumeraycaster.h>
 #include <openspace/scene/scene.h>
 #include <openspace/util/camera.h>
@@ -260,7 +261,12 @@ void ABufferRenderer::render(float blackoutFactor, bool doPerformanceMeasurement
     glBindImageTexture(1, _fragmentTexture, 0, GL_FALSE, 0, GL_READ_WRITE, GL_RGBA32UI);
 
     // Render the scene to the fragment buffer. Collect renderer tasks (active raycasters)
-    RenderData data{ *_camera, psc(), doPerformanceMeasurements };
+    int renderBinMask = static_cast<int>(Renderable::RenderBin::Background) |
+        static_cast<int>(Renderable::RenderBin::Opaque) |
+        static_cast<int>(Renderable::RenderBin::Transparent) |
+        static_cast<int>(Renderable::RenderBin::Overlay);
+
+    RenderData data{ *_camera, psc(), doPerformanceMeasurements, renderBinMask };
     RendererTasks tasks;
     _scene->render(data, tasks);
 

src/rendering/framebufferrenderer.cpp

@@ -30,6 +30,7 @@
 #include <openspace/scene/scene.h>
 #include <openspace/util/camera.h>
 #include <openspace/engine/openspaceengine.h>
+#include <openspace/rendering/renderable.h>
 #include <openspace/rendering/volumeraycaster.h>
 #include <openspace/rendering/raycastermanager.h>
 
@@ -329,7 +330,7 @@ void FramebufferRenderer::render(float blackoutFactor, bool doPerformanceMeasure
     glEnable(GL_BLEND);
     glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 
-    RenderData data = { *_camera, psc(), doPerformanceMeasurements };
+    RenderData data = { *_camera, psc(), doPerformanceMeasurements, 0 };
     RendererTasks tasks;
 
     // Capture standard fbo
@@ -339,7 +340,13 @@ void FramebufferRenderer::render(float blackoutFactor, bool doPerformanceMeasure
     glBindFramebuffer(GL_FRAMEBUFFER, _mainFramebuffer);
     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
-    // bind new fbo A with color and depth buffer.
+    data.renderBinMask = static_cast<int>(Renderable::RenderBin::Background);
+    _scene->render(data, tasks);
+    data.renderBinMask = static_cast<int>(Renderable::RenderBin::Opaque);
+    _scene->render(data, tasks);
+    data.renderBinMask = static_cast<int>(Renderable::RenderBin::Transparent);
+    _scene->render(data, tasks);
+    data.renderBinMask = static_cast<int>(Renderable::RenderBin::Overlay);
     _scene->render(data, tasks);
 
     for (const RaycasterTask& raycasterTask : tasks.raycasterTasks) {

src/rendering/renderable.cpp

@@ -72,6 +72,7 @@ Renderable* Renderable::createFromDictionary(const ghoul::Dictionary& dictionary
 
 Renderable::Renderable()
     : _enabled("enabled", "Is Enabled", true)
+    , _renderBin(RenderBin::Opaque)
     , _startTime("")
     , _endTime("")
     , _targetBody("")
@@ -83,6 +84,7 @@ Renderable::Renderable()
 
 Renderable::Renderable(const ghoul::Dictionary& dictionary)
     : _enabled("enabled", "Is Enabled", true)
+    , _renderBin(RenderBin::Opaque)
     , _startTime("")
     , _endTime("")
     , _targetBody("")
@@ -148,6 +150,18 @@ void Renderable::setPscUniforms(
     program.setUniform("scaling", camera.scaling());
 }
 
+Renderable::RenderBin Renderable::renderBin() const {
+    return _renderBin;
+}
+
+void Renderable::setRenderBin(RenderBin bin) {
+    _renderBin = bin;
+}
+
+bool Renderable::matchesRenderBinMask(int binMask) {
+    return binMask & static_cast<int>(renderBin());
+}
+
 bool Renderable::isVisible() const {
     return _enabled;
 }

src/scene/scenegraphnode.cpp

@@ -248,7 +248,14 @@ void SceneGraphNode::render(const RenderData& data, RendererTasks& tasks) {
     RenderData newData = {data.camera, thisPosition, data.doPerformanceMeasurement};
 
     _performanceRecord.renderTime = 0;
-    if (_renderableVisible && _renderable->isVisible() && _renderable->isReady() && _renderable->isEnabled()) {
+
+    bool visible = _renderableVisible &&
+        _renderable->isVisible() &&
+        _renderable->isReady() &&
+        _renderable->isEnabled() &&
+        _renderable->matchesRenderBinMask(data.renderBinMask);
+
+    if (visible) {
         if (data.doPerformanceMeasurement) {
             glFinish();
             auto start = std::chrono::high_resolution_clock::now();