iOS: Clean up promotion of EAGLLayer use down to FBObject

Initial commit bba73bc096250a3c7fc036d84b1ea054d1b70b06 hacked
its path using a context global EGLLayer instance attachement.
The hack was good for the first demo, however, it forbid using
other FBObjects etc on the way.

Properly specifying FBObject.Attachment.StorageDefinition,
allowing the user to inject code for selected FBO attachements
to define their storage. This might be useful for different
platforms as well - however, it is OS agnostic and instance specific now.

In this sense, GLFBODrawableImpl, hosting FBObject,
has a more specific instance of FBObject.Attachment.StorageDefinition
for color-renderbuffer. It is passed along newly created color renderbuffer.

GLDrawableFactoryImpl.createGLDrawable uses a derived interface,
OnscreenFBOColorbufferStorageDefinition which is defined in
IOSEAGLDrawableFactory and return by its getter.
GLDrawableFactoryImpl.createGLDrawable is therefor platform agnostic again.

Bottom line is, as more platforms will be added, these semi-public interfaces
have to adapt to suit them all ..

All this due to iOS architecture for 'onscreen rendering' using a FBO
which shares its color renderbuffer storage with the EAGLLayer,
associated with the UIView. A bit weird maybe in first sight,
but efficient for creating cheap hardware design ;-)
Only criticism here is that Apple didn't bother using EGL and an extension.

4 files changed, 162 insertions, 91 deletions

diff --git a/src/jogl/classes/jogamp/opengl/GLDrawableFactoryImpl.java b/src/jogl/classes/jogamp/opengl/GLDrawableFactoryImpl.java
index 2e108d3ce..fad77d76d 100644
--- a/src/jogl/classes/jogamp/opengl/GLDrawableFactoryImpl.java
+++ b/src/jogl/classes/jogamp/opengl/GLDrawableFactoryImpl.java
@@ -55,6 +55,7 @@ import com.jogamp.nativewindow.OffscreenLayerSurface;
 import com.jogamp.nativewindow.ProxySurface;
 import com.jogamp.nativewindow.MutableSurface;
 import com.jogamp.nativewindow.UpstreamSurfaceHook;
+import com.jogamp.opengl.FBObject;
 import com.jogamp.opengl.GLAutoDrawable;
 import com.jogamp.opengl.GLCapabilities;
 import com.jogamp.opengl.GLCapabilitiesChooser;
@@ -68,7 +69,6 @@ import com.jogamp.opengl.GLOffscreenAutoDrawable;
 import com.jogamp.opengl.GLProfile;
 
 import com.jogamp.common.ExceptionUtils;
-import com.jogamp.common.os.Platform;
 import com.jogamp.nativewindow.MutableGraphicsConfiguration;
 import com.jogamp.nativewindow.DelegatedUpstreamSurfaceHookWithSurfaceSize;
 import com.jogamp.nativewindow.GenericUpstreamSurfacelessHook;
@@ -76,9 +76,6 @@ import com.jogamp.nativewindow.UpstreamSurfaceHookMutableSize;
 import com.jogamp.opengl.GLAutoDrawableDelegate;
 import com.jogamp.opengl.GLRendererQuirks;
 
-import jogamp.common.os.PlatformPropsImpl;
-
-
 /** Extends GLDrawableFactory with a few methods for handling
     typically software-accelerated offscreen rendering (Device
     Independent Bitmaps on Windows, pixmaps on X11). Direct access to
@@ -264,6 +261,36 @@ public abstract class GLDrawableFactoryImpl extends GLDrawableFactory {
    */
   public abstract GLDynamicLookupHelper getGLDynamicLookupHelper(final int majorVersion, final int contextOptions);
 
+  /**
+   * Extends definition of {@link FBObject.Attachment.StorageDefinition}
+   * for general onscreen FBO layer storage requirements.
+   * <p>
+   * Implementations are allowed to specialize {@link FBObject.Attachment.StorageDefinition}
+   * for the special use-case of:
+   * <ul>
+   *   <li>Using an underlying {@link FBObject} for onscreen rendering, hence {@link #createGLDrawable(NativeSurface)}, and</li>
+   *   <li>Using a special <i>color renderbuffer storage</i> instead of the default {@link FBObject} <i>internal offscreen</i> storage.</li>
+   * </ul>
+   * </p>
+   * @see {@link FBObject.Attachment.StorageDefinition}
+   * @see {@link FBObject.Attachment#setStorageDefinition(FBObject.Attachment.StorageDefinition)}
+   */
+  public static interface OnscreenFBOColorbufferStorageDefinition extends FBObject.Attachment.StorageDefinition {
+      /**
+       * Returns true if underlying implementation supports double buffering
+       */
+      public boolean isDoubleBufferSupported();
+      /**
+       * Texture-Unit to be used for the FBO colorbuffer.
+       * <p>
+       * If a valid unit is returned, i.e. >= 0, a color texturebuffer is used, otherwise a color renderbuffer.
+       * </p>
+       */
+      public int getTextureUnit();
+  }
+
+  protected OnscreenFBOColorbufferStorageDefinition getOnscreenFBOColorbufStorageDef() { return null; }
+
   //---------------------------------------------------------------------------
   // Dispatching GLDrawable construction in respect to the NativeSurface Capabilities
   //
@@ -273,29 +300,41 @@ public abstract class GLDrawableFactoryImpl extends GLDrawableFactory {
       throw new IllegalArgumentException("Null target");
     }
     final MutableGraphicsConfiguration config = (MutableGraphicsConfiguration) target.getGraphicsConfiguration();
+    final GLCapabilitiesImmutable reqCaps = (GLCapabilitiesImmutable) config.getRequestedCapabilities();
     final GLCapabilitiesImmutable chosenCaps = (GLCapabilitiesImmutable) config.getChosenCapabilities();
     final AbstractGraphicsDevice adevice = config.getScreen().getDevice();
     final boolean isFBOAvailable = GLContext.isFBOAvailable(adevice, chosenCaps.getGLProfile());
     GLDrawable result = null;
     adevice.lock();
     try {
+        final OnscreenFBOColorbufferStorageDefinition onscreenFBOColorbufStorageDef = getOnscreenFBOColorbufStorageDef();
         final boolean forceOnscreenFBOLayer;
-        final boolean useFBORendertarget;
-        if( chosenCaps.isOnscreen() && Platform.OSType.IOS == PlatformPropsImpl.OS_TYPE )  // FIXME: avoid hardcoding?
-        {
+        final int fboTextureUnit;
+        if( reqCaps.isOnscreen() && null != onscreenFBOColorbufStorageDef) {
             forceOnscreenFBOLayer = true;
-            useFBORendertarget = true;
+            fboTextureUnit = onscreenFBOColorbufStorageDef.getTextureUnit();
         } else {
             forceOnscreenFBOLayer = false;
-            useFBORendertarget = false;
+            fboTextureUnit = 0; // assume texture unit 0 (default) is used at all
         }
         final OffscreenLayerSurface ols = NativeWindowFactory.getOffscreenLayerSurface(target, true);
         if(null != ols || forceOnscreenFBOLayer ) {
-            final GLCapabilitiesImmutable chosenCapsMod = GLGraphicsConfigurationUtil.fixOffscreenGLCapabilities(chosenCaps, this, adevice);
-
-            // layered surface -> Offscreen/[FBO|PBuffer]
-            if( !chosenCapsMod.isFBO() && !chosenCapsMod.isPBuffer() ) {
-                throw new GLException("Neither FBO nor Pbuffer is available for "+chosenCapsMod+", "+target);
+            final GLCapabilitiesImmutable chosenCapsMod0 = GLGraphicsConfigurationUtil.fixOffscreenGLCapabilities(chosenCaps, this, adevice);
+            final GLCapabilitiesImmutable chosenCapsMod;
+            if( forceOnscreenFBOLayer && !onscreenFBOColorbufStorageDef.isDoubleBufferSupported() ) {
+                chosenCapsMod = GLGraphicsConfigurationUtil.fixDoubleBufferedGLCapabilities(chosenCapsMod0, false);
+            } else {
+                chosenCapsMod = chosenCapsMod0;
+            }
+            if( forceOnscreenFBOLayer ) {
+                if( !chosenCapsMod.isFBO() ) {
+                    throw new GLException("FBO is not available for "+chosenCapsMod+", "+target);
+                }
+            } else {
+                // layered surface -> Offscreen/[FBO|PBuffer]
+                if( !chosenCapsMod.isFBO() && !chosenCapsMod.isPBuffer() ) {
+                    throw new GLException("Neither FBO nor Pbuffer is available for "+chosenCapsMod+", "+target);
+                }
             }
             config.setChosenCapabilities(chosenCapsMod);
             if( null != ols ) {
@@ -303,10 +342,11 @@ public abstract class GLDrawableFactoryImpl extends GLDrawableFactory {
             }
             if(DEBUG) {
                 System.err.println("GLDrawableFactoryImpl.createGLDrawable -> OnscreenDrawable -> Offscreen-Layer");
+                System.err.println("requestedCaps: "+reqCaps);
                 System.err.println("chosenCaps:    "+chosenCaps);
                 System.err.println("chosenCapsMod: "+chosenCapsMod);
                 System.err.println("OffscreenLayerSurface: **** "+ols);
-                System.err.println("forceOnscreenFBOLayer: **** "+forceOnscreenFBOLayer+", useFBORendertarget "+useFBORendertarget);
+                System.err.println("forceOnscreenFBOLayer: **** "+forceOnscreenFBOLayer+", fboTextureUnit "+fboTextureUnit);
                 System.err.println("Target: **** "+target);
                 ExceptionUtils.dumpStack(System.err);
             }
@@ -314,7 +354,11 @@ public abstract class GLDrawableFactoryImpl extends GLDrawableFactory {
                 throw new IllegalArgumentException("Passed NativeSurface must implement SurfaceChangeable for offscreen layered surface: "+target);
             }
             if( chosenCapsMod.isFBO() ) {
-                result = createFBODrawableImpl(target, chosenCapsMod, useFBORendertarget?-1:0);
+                final GLFBODrawableImpl fboDrawable = (GLFBODrawableImpl) createFBODrawableImpl(target, chosenCapsMod, fboTextureUnit);
+                if( forceOnscreenFBOLayer ) {
+                    fboDrawable.setColorRenderbufferStorageDef(onscreenFBOColorbufStorageDef);
+                }
+                result = fboDrawable;
             } else {
                 result = createOffscreenDrawableImpl(target);
             }
@@ -523,7 +567,13 @@ public abstract class GLDrawableFactoryImpl extends GLDrawableFactory {
     }
   }
 
-  /** Creates a platform independent unrealized FBO offscreen GLDrawable */
+  /**
+   * Creates a platform independent unrealized FBO offscreen GLDrawable
+   * @param dummySurface used for dummy-drawable and as surface for {@link GLFBODrawable}
+   * @param fboCaps
+   * @param textureUnit if valid, i.e. >= 0, signals using a color texturebuffer {@link GLFBODrawable#FBOMODE_USE_TEXTURE}, otherwise a color renderbuffer is used.
+   * @return
+   */
   protected final GLFBODrawable createFBODrawableImpl(final NativeSurface dummySurface, final GLCapabilitiesImmutable fboCaps, final int textureUnit) {
     final GLDrawableImpl dummyDrawable = createOnscreenDrawableImpl(dummySurface);
     return new GLFBODrawableImpl(this, dummyDrawable, dummySurface, fboCaps, textureUnit);
diff --git a/src/jogl/classes/jogamp/opengl/GLFBODrawableImpl.java b/src/jogl/classes/jogamp/opengl/GLFBODrawableImpl.java
index 64cca7bdd..ea226b407 100644
--- a/src/jogl/classes/jogamp/opengl/GLFBODrawableImpl.java
+++ b/src/jogl/classes/jogamp/opengl/GLFBODrawableImpl.java
@@ -76,6 +76,7 @@ public class GLFBODrawableImpl extends GLDrawableImpl implements GLFBODrawable {
 
     // private DoubleBufferMode doubleBufferMode; // TODO: Add or remove TEXTURE (only) DoubleBufferMode support
 
+    private FBObject.Attachment.StorageDefinition colorRenderbufferStorageDef;
     private SwapBufferContext swapBufferContext;
 
     public static interface SwapBufferContext {
@@ -87,7 +88,7 @@ public class GLFBODrawableImpl extends GLDrawableImpl implements GLFBODrawable {
      * @param parent
      * @param surface
      * @param fboCaps the requested FBO capabilities
-     * @param textureUnit if valid, i.e. >= 0, signals {@link #FBOMODE_USE_TEXTURE}, otherwise a color renderbuffer is assumed
+     * @param textureUnit if valid, i.e. >= 0, signals using a color texturebuffer {@link GLFBODrawable#FBOMODE_USE_TEXTURE}, otherwise a color renderbuffer is used.
      */
     protected GLFBODrawableImpl(final GLDrawableFactoryImpl factory, final GLDrawableImpl parent, final NativeSurface surface,
                                 final GLCapabilitiesImmutable fboCaps, final int textureUnit) {
@@ -100,6 +101,7 @@ public class GLFBODrawableImpl extends GLDrawableImpl implements GLFBODrawable {
         this.texUnit = textureUnit>=0 ? textureUnit : 0;
         this.samples = fboCaps.getNumSamples();
         this.fboResetQuirk = false;
+        this.colorRenderbufferStorageDef = null;
         this.swapBufferContext = null;
     }
 
@@ -117,7 +119,11 @@ public class GLFBODrawableImpl extends GLDrawableImpl implements GLFBODrawable {
             throw new InternalError("Sample number mismatch: "+samples+", fbos["+idx+"] "+fbo);
         }
         if(samples > 0 || !useTexture) {
-            fbo.attachColorbuffer(gl, 0, useAlpha);
+            final FBObject.ColorAttachment ca = fbo.createColorAttachment(useAlpha);
+            if( null != colorRenderbufferStorageDef ) {
+                ca.setStorageDefinition(colorRenderbufferStorageDef);
+            }
+            fbo.attachColorbuffer(gl, 0, ca);
         } else {
             fbo.attachTexture2D(gl, 0, useAlpha);
         }
@@ -135,7 +141,11 @@ public class GLFBODrawableImpl extends GLDrawableImpl implements GLFBODrawable {
             {
                 ssink.init(gl, width, height, 0);
                 if( !useTexture ) {
-                    ssink.attachColorbuffer(gl, 0, useAlpha);
+                    final FBObject.ColorAttachment ca = ssink.createColorAttachment(useAlpha);
+                    if( null != colorRenderbufferStorageDef ) {
+                        ca.setStorageDefinition(colorRenderbufferStorageDef);
+                    }
+                    ssink.attachColorbuffer(gl, 0, ca);
                 } else {
                     ssink.attachTexture2D(gl, 0, useAlpha);
                 }
@@ -249,6 +259,24 @@ public class GLFBODrawableImpl extends GLDrawableImpl implements GLFBODrawable {
         swapBufferContext = sbc;
     }
 
+    /**
+     * Inject custom {@link FBObject.Attachment.StorageDefinition} specialization for the use-case of:
+     * <ul>
+     *   <li>Using a special <i>color renderbuffer storage</i> instead of the default {@link FBObject} <i>internal offscreen</i> storage.</li>
+     * </ul>
+     * @see {@link FBObject.Attachment.StorageDefinition}
+     * @see {@link FBObject.Attachment#setStorageDefinition(FBObject.Attachment.StorageDefinition)}
+     */
+    public final void setColorRenderbufferStorageDef(final FBObject.Attachment.StorageDefinition sd) {
+        colorRenderbufferStorageDef = sd;
+        if(DEBUG) {
+            System.err.println("EAGL.FBODrawable: setColorRenderbufferStorageDef");
+        }
+    }
+    public final boolean hasColorRenderbufferStorageDef(final FBObject.Attachment.StorageDefinition sd) {
+        return sd == colorRenderbufferStorageDef;
+    }
+
     private final void reset(final GL gl, final int idx, final int width, final int height, final int samples,
                              final boolean useAlpha, final int depthBits, final int stencilBits) {
         if( !fboResetQuirk ) {
diff --git a/src/jogl/classes/jogamp/opengl/ios/eagl/IOSEAGLContext.java b/src/jogl/classes/jogamp/opengl/ios/eagl/IOSEAGLContext.java
index 57c20d465..e3b7a64a7 100644
--- a/src/jogl/classes/jogamp/opengl/ios/eagl/IOSEAGLContext.java
+++ b/src/jogl/classes/jogamp/opengl/ios/eagl/IOSEAGLContext.java
@@ -34,19 +34,18 @@ import com.jogamp.nativewindow.AbstractGraphicsConfiguration;
 import com.jogamp.nativewindow.AbstractGraphicsDevice;
 import com.jogamp.nativewindow.MutableGraphicsConfiguration;
 import com.jogamp.nativewindow.OffscreenLayerSurface;
-import com.jogamp.opengl.FBObject;
 import com.jogamp.opengl.GL;
 import com.jogamp.opengl.GLCapabilitiesImmutable;
 import com.jogamp.opengl.GLContext;
 import com.jogamp.opengl.GLException;
-import com.jogamp.opengl.GLFBODrawable;
 import com.jogamp.opengl.GLProfile;
 
-import jogamp.nativewindow.ios.IOSUtil;
 import jogamp.opengl.GLContextImpl;
+import jogamp.opengl.GLDrawableFactoryImpl;
 import jogamp.opengl.GLDrawableImpl;
 import jogamp.opengl.GLDynamicLookupHelper;
 import jogamp.opengl.GLFBODrawableImpl;
+import jogamp.opengl.GLDrawableFactoryImpl.OnscreenFBOColorbufferStorageDefinition;
 import jogamp.opengl.GLFBODrawableImpl.SwapBufferContext;
 import jogamp.opengl.DummyGLExtProcAddressTable;
 import jogamp.opengl.ios.eagl.IOSEAGLDrawable.GLBackendType;
@@ -100,8 +99,6 @@ public class IOSEAGLContext extends GLContextImpl
   // CGL extension functions.
   private DummyGLExtProcAddressTable cglExtProcAddressTable;
 
-  private int lastWidth, lastHeight;
-
   protected IOSEAGLContext(final GLDrawableImpl drawable,
                    final GLContext shareWith) {
     super(drawable, shareWith);
@@ -194,11 +191,6 @@ public class IOSEAGLContext extends GLContextImpl
 
   @Override
   protected void makeCurrentImpl() throws GLException {
-    /** FIXME: won't work w/ special drawables (like FBO) - check for CGL mode regressions!
-     *
-    if (getOpenGLMode() != ((IOSEAGLDrawable)drawable).getOpenGLMode()) {
-      setOpenGLMode(((IOSEAGLDrawable)drawable).getOpenGLMode());
-    } */
     if ( !impl.makeCurrent(contextHandle) ) {
       throw new GLException("Error making Context current: "+this);
     }
@@ -221,50 +213,48 @@ public class IOSEAGLContext extends GLContextImpl
 
   @Override
   protected void drawableUpdatedNotify() throws GLException {
-    if( drawable.getChosenGLCapabilities().isOnscreen() ) {
-        final int w = drawable.getSurfaceWidth();
-        final int h = drawable.getSurfaceHeight();
-        // final boolean sizeChanged = w != lastWidth || h != lastHeight;
-        if(drawable instanceof GLFBODrawable) {
-            final GLFBODrawable fbod = (GLFBODrawable) drawable;
-            final FBObject.Colorbuffer col = fbod.getColorbuffer(GL.GL_FRONT); // FIXME GL_BACK swap ..
-            final int renderbuffer = col.getName();
-            EAGL.eaglPresentRenderbuffer(contextHandle, renderbuffer);
-        }
-        // TODO: Check for resize ...
-        lastWidth = w;
-        lastHeight = h;
-    }
+      // NOTE to resize: GLFBODrawableImpl.resetSize(GL) called from many
+      // high level instances in the GLDrawable* space,
+      // e.g. GLAutoDrawableBase's defaultWindowResizedOp(..)
   }
 
   @Override
   protected void associateDrawable(final boolean bound) {
       // context stuff depends on drawable stuff
-      if(bound) {
+      final GLFBODrawableImpl fboDrawable;
+      final boolean taggedOnscreenFBOEAGLLayer;
+      {
           final GLDrawableImpl drawable = getDrawableImpl();
-          if( drawable instanceof GLFBODrawableImpl ) {
-              final GLFBODrawableImpl fboDrawable = (GLFBODrawableImpl) drawable;
+          final GLDrawableFactoryImpl factory = drawable.getFactoryImpl();
+          final IOSEAGLDrawableFactory iosFactory = (factory instanceof IOSEAGLDrawableFactory) ? (IOSEAGLDrawableFactory) factory : null;
+          final OnscreenFBOColorbufferStorageDefinition onscreenFBOColorbufStorageDef = (null != iosFactory) ? iosFactory.getOnscreenFBOColorbufStorageDef() : null;
+
+          fboDrawable = (drawable instanceof GLFBODrawableImpl) ? (GLFBODrawableImpl)drawable : null;
+          taggedOnscreenFBOEAGLLayer = (null != fboDrawable && null != onscreenFBOColorbufStorageDef) ?
+                  fboDrawable.hasColorRenderbufferStorageDef(onscreenFBOColorbufStorageDef) : false;
+      }
+      if( DEBUG ) {
+          System.err.println(getThreadName() + ": IOSEAGLContext.associateDrawable(bound "+bound+"): taggedOnscreenFBOEAGLLayer "+taggedOnscreenFBOEAGLLayer+
+                             ", hasFBODrawable "+(null != fboDrawable)+", drawable: "+getDrawableImpl().getClass().getName());
+      }
+      if(bound) {
+          if( taggedOnscreenFBOEAGLLayer ) {
+              // Done in GLDrawableFactory.createGDrawable(..) for onscreen drawables:
+              // fboDrawable.setColorRenderbufferStorageDef(iosFactory.getOnscreenFBOColorbufStorageDef());
               fboDrawable.setSwapBufferContext(new SwapBufferContext() {
                   @Override
                   public void swapBuffers(final boolean doubleBuffered) {
                       EAGL.eaglPresentRenderbuffer(contextHandle, GL.GL_RENDERBUFFER);
                   } } );
           }
-          // FIXME: Need better way to inject the IOS EAGL Layer into FBObject
-          // FIXME: May want to implement optional injection of a BufferStorage SPI?
-          // FBObject.ColorAttachment.initialize(GL): EAGL.eaglBindDrawableStorageToRenderbuffer(contextHandle, GL.GL_RENDERBUFFER, eaglLayer);
-          final long eaglLayer = IOSUtil.GetCAEAGLLayer(drawable.getNativeSurface().getSurfaceHandle());
-          System.err.println("EAGL: Ctx attach EAGLLayer 0x"+Long.toHexString(eaglLayer));
-          attachObject("IOS_EAGL_LAYER", new Long(eaglLayer));
-
           super.associateDrawable(true);   // 1) init drawable stuff (FBO init, ..)
           impl.associateDrawable(true);    // 2) init context stuff
       } else {
           impl.associateDrawable(false);   // 1) free context stuff
           super.associateDrawable(false);  // 2) free drawable stuff
-
-          EAGL.eaglBindDrawableStorageToRenderbuffer(contextHandle, GL.GL_RENDERBUFFER, 0);
-          detachObject("IOS_EAGL_LAYER");
+          if( taggedOnscreenFBOEAGLLayer ) {
+              EAGL.eaglBindDrawableStorageToRenderbuffer(contextHandle, GL.GL_RENDERBUFFER, 0);
+          }
       }
   }
 
@@ -361,40 +351,6 @@ public class IOSEAGLContext extends GLContextImpl
       @Override
       public boolean isUsingCAEAGLLayer() { return null != backingLayerHost; }
 
-      /** Only returns a valid UIView. If !UIView, return null and mark isFBO or isSurfaceless. */
-      private long getUIViewHandle(final boolean[] isFBO, final boolean[] isSurfaceless) {
-          final long uiViewHandle;
-          if(drawable instanceof GLFBODrawableImpl) {
-              uiViewHandle = 0;
-              isFBO[0] = true;
-              isSurfaceless[0] = false;
-              if(DEBUG) {
-                  System.err.println("UI viewHandle.1: GLFBODrawableImpl drawable: isFBO "+isFBO[0]+", isSurfaceless "+isSurfaceless[0]+", "+drawable.getClass().getName()+",\n\t"+drawable);
-              }
-          } else {
-              final long drawableHandle = drawable.getHandle();
-              final boolean isUIView = IOSUtil.isUIView(drawableHandle);
-              final boolean isUIWindow = IOSUtil.isUIWindow(drawableHandle);
-              isFBO[0] = false;
-              isSurfaceless[0] = false;
-
-              if( isUIView ) {
-                  uiViewHandle = drawableHandle;
-              } else if( isUIWindow ) {
-                  uiViewHandle = IOSUtil.GetUIView(drawableHandle, true /* only EAGL */);
-              } else if( isSurfaceless() ) {
-                  isSurfaceless[0] = true;
-                  uiViewHandle = 0;
-              } else {
-                  throw new GLException("Drawable's handle neither NSView, NSWindow nor PBuffer: drawableHandle "+toHexString(drawableHandle)+", isNSView "+isUIView+", isNSWindow "+isUIWindow+", isFBO "+isFBO[0]+", "+drawable.getClass().getName()+",\n\t"+drawable);
-              }
-              if(DEBUG) {
-                  System.err.println("NS viewHandle.2: drawableHandle "+toHexString(drawableHandle)+" -> nsViewHandle "+toHexString(uiViewHandle)+": isNSView "+isUIView+", isNSWindow "+isUIWindow+", isFBO "+isFBO[0]+", isSurfaceless "+isSurfaceless[0]+", "+drawable.getClass().getName()+",\n\t"+drawable);
-              }
-          }
-          return uiViewHandle;
-      }
-
       @Override
       public long create(final long share, final int ctp, final int major, final int minor) {
           long ctx = 0;
diff --git a/src/jogl/classes/jogamp/opengl/ios/eagl/IOSEAGLDrawableFactory.java b/src/jogl/classes/jogamp/opengl/ios/eagl/IOSEAGLDrawableFactory.java
index 3c3f1edb8..71904d1a6 100644
--- a/src/jogl/classes/jogamp/opengl/ios/eagl/IOSEAGLDrawableFactory.java
+++ b/src/jogl/classes/jogamp/opengl/ios/eagl/IOSEAGLDrawableFactory.java
@@ -41,6 +41,7 @@ import com.jogamp.nativewindow.NativeSurface;
 import com.jogamp.nativewindow.ProxySurface;
 import com.jogamp.nativewindow.UpstreamSurfaceHook;
 import com.jogamp.nativewindow.ios.IOSGraphicsDevice;
+import com.jogamp.opengl.FBObject;
 import com.jogamp.opengl.GL;
 import com.jogamp.opengl.GLCapabilities;
 import com.jogamp.opengl.GLCapabilitiesChooser;
@@ -52,6 +53,7 @@ import com.jogamp.opengl.GLProfile;
 
 import jogamp.nativewindow.WrappedSurface;
 import jogamp.nativewindow.ios.IOSDummyUpstreamSurfaceHook;
+import jogamp.nativewindow.ios.IOSUtil;
 import jogamp.opengl.GLContextImpl;
 import jogamp.opengl.GLDrawableFactoryImpl;
 import jogamp.opengl.GLDrawableImpl;
@@ -62,6 +64,8 @@ import jogamp.opengl.SharedResourceRunner;
 import com.jogamp.nativewindow.GenericUpstreamSurfacelessHook;
 import com.jogamp.opengl.GLExtensions;
 import com.jogamp.opengl.GLRendererQuirks;
+import com.jogamp.opengl.FBObject.Attachment;
+import com.jogamp.opengl.FBObject.Attachment.StorageDefinition;
 
 public class IOSEAGLDrawableFactory extends GLDrawableFactoryImpl {
   private static final boolean DEBUG_SHAREDCTX = DEBUG  || GLContext.DEBUG;
@@ -343,6 +347,39 @@ public class IOSEAGLDrawableFactory extends GLDrawableFactoryImpl {
   }
 
   @Override
+  protected final OnscreenFBOColorbufferStorageDefinition getOnscreenFBOColorbufStorageDef() { return onscreenGLDrawableFBOColorRenderbufferStorageDef; }
+  private final OnscreenFBOColorbufferStorageDefinition onscreenGLDrawableFBOColorRenderbufferStorageDef = new OnscreenFBOColorbufferStorageDefinition() {
+                @Override
+                public final void setStorage(final GL gl, final Attachment a) {
+                    final int samples = ((FBObject.RenderAttachment) a).getSamples();
+                    if( samples > 0 ) {
+                        gl.glRenderbufferStorageMultisample(GL.GL_RENDERBUFFER, samples, a.format, a.getWidth(), a.getHeight());
+                    } else {
+                        // gl.glRenderbufferStorage(GL.GL_RENDERBUFFER, a.format, a.getWidth(), a.getHeight());
+                        final long eaglLayer = IOSUtil.GetCAEAGLLayer(gl.getContext().getGLDrawable().getNativeSurface().getSurfaceHandle());
+                        EAGL.eaglBindDrawableStorageToRenderbuffer(gl.getContext().getHandle(), GL.GL_RENDERBUFFER, eaglLayer);
+                        if( DEBUG ) {
+                            System.err.println("EAGL.eaglBindDrawableStorageToRenderbuffer: ctx 0x"+Long.toHexString(gl.getContext().getHandle()) +
+                                               ", eaglLayer 0x"+Long.toHexString(eaglLayer));
+                        }
+                    }
+                }
+                @Override
+                public final boolean isDoubleBufferSupported() {
+                    return false;
+                }
+                @Override
+                public final int getTextureUnit() {
+                    return -1; // force using a color renderbuffer
+                } };
+
+  /**
+   * {@inheritDoc}
+   * <p>
+   * This IOS <i>onscreen drawable</i> implementation actually is only a dummy implementation
+   * </p>
+   */
+  @Override
   protected GLDrawableImpl createOnscreenDrawableImpl(final NativeSurface target) {
     if (target == null) {
       throw new IllegalArgumentException("Null target");