Update usage infos

README.md

@@ -24,23 +24,28 @@ repositories {
     maven { url  "https://dl.bintray.com/riccardo/effekseer" }
 }
 dependencies {
-	implementation 'com.github.riccardobl:jme-effekseerNative:-SNAPSHOT'
+    implementation 'com.github.riccardobl:jme-effekseerNative:-SNAPSHOT'
 }
 
 ```
 
 
-## Usage
+## Usage - Managed Rendering
 ```java
 // Add a filter post processor to your viewPort
-FilterPostProcessor fpp=new FilterPostProcessor(assetManager);
- viewPort.addProcessor(fpp);
+// optional:
+//   if the FilterPostProcessor is created, EffekseerRenderer will attach itself as a filter
+//   otherwise it will be attached as a scene processor.
+//   Note: if a FilterPostProcessor is used in the viewport, EffekseerRenderer must be called before 
+//         attaching any other filter, becoming defacto the first filter to be attached to the FilterPostProcessor
+// FilterPostProcessor fpp=new FilterPostProcessor(assetManager);
+// viewPort.addProcessor(fpp);
 
 // Add Effekseer Renderer
-fpp.addFilter(new EffekseerPostRenderer(assetManager));
+EffekseerRenderer effekseerRenderer=EffekseerRenderer.addToViewPort(stateManager, viewPort, assetManager, settings.isGammaCorrection());
 
 // Load an effect
-EffekseerEmitterControl effekt=(EffekseerEmitterControl)assetManager.loadAsset("effekts/Pierre/Lightning.efkefc");
+EffekseerEmitterControl effekt=new EffekseerEmitterControl(assetManager,"effekts/Pierre/Lightning.efkefc");
 
 // Set a driver (optional)
 effekt.setDriver(
@@ -54,7 +59,6 @@ effekt.setDriver(
 Node n=new Node();
 n.addControl(effekt);
 
-
 rootNode.attachChild(n);
 
 ```
@@ -63,22 +67,61 @@ rootNode.attachChild(n);
 This is intended to be used on custom render pipelines or offscreen rendering
 ```java
 // Init Effekseer
-Effekseer.init(assetManager);
-
-// Select the scene to render (only child of root will be renderer). root=null to render all.
-Effekseer.beginScene(root);
+boolean isSRGB=true;
+Effekseer.init(assetManager,isSRGB);
 
-// Update the logic
+// Update logic: This needs to be called in your update loop (once per frame)
 Effekseer.update( tpf);
 
+// --- Render scene 1
+// Select the scene to render
+Effekseer.beginRender(root1);
+
+// Render
+Effekseer.render(
+	Renderer, /* The opengl renderer */
+	Camera, /* The scene camera */
+	FrameBuffer, /* The render target */
+	Texture2D, /* The depth texture of the current scene (for soft particles, null to disable soft particles) */
+	Float, /* Particles hardness (for soft particles) */
+	Float, /* Particles contrast (for soft particles) */
+	Boolean /* True if rendering on 2d Target */
+);
+
+// End the render
+Effekseer.endRender();
+
+// --- Render scene 2
+// Select the scene to render
+Effekseer.beginRender(root2);
+
 // Render
-// sceneDepth is the depth of the current scene - used for soft particles
-Effekseer.render(Renderer renderer,Camera cam,FrameBuffer renderTarget,Texture sceneDepth);
+Effekseer.render(
+	Renderer, /* The opengl renderer */
+	Camera, /* The scene camera */
+	FrameBuffer, /* The render target */
+	Texture2D, /* The depth texture of the current scene (for soft particles, null to disable soft particles) */
+	Float, /* Particles hardness (for soft particles) */
+	Float, /* Particles contrast (for soft particles) */
+	Boolean /* True if rendering on 2d Target */
+);
 
-// End the scene, reset states
-Effekseer.endScene();
+// End the render
+Effekseer.endRender();
 
 ```
 
+Note: opengl cannot read and write on the same target, this means that depth that comes from the same target framebuffer has to be copied.
+The following helper utility can be used to do it in a reasonably fast way (it used glBlitFramebuffer and a pool of cached framebuffers internally):
+```java
+Texture copiedDepth=EffekseerUtils.copyDepthFromFrameBuffer(
+	RenderManager, /* the render manager */
+	FrameBuffer, /* source */
+	int, /* width */
+	int /* height */
+);
+```
 
+### Limitations
+- There is an issue with depth sorting when using *Managed Rendering* to render inside the SimpleApplication's guiViewPort: the particles will always be rendered on top. Finding a generic workaround for this issue is pretty complex due to the way the engine handles the guiViewPort. A possible solution is to use *Advanced Usage - Manual Rendering* to render a special root node containing only "gui particles" on top of the main framebuffer using an appropriate Camera.