Cleanup GLContext special entries: getOffscreenContextPixelDataType(), getOffscreenContextReadBuffer(), .. ; Add GLFBODrawable API entries for multi buffering (no impl. yet); GLJPanel 1st simplification using offscreen drawable

- Cleanup GLContext special entries: getOffscreenContextPixelDataType(), getOffscreenContextReadBuffer(), .. ;
  - add: getDefaultReadBuffer() (-> exposed via GLBase as well)
  - add: isGLOrientationFlippedVertical()
  - add: getDefaultPixelDataType()
  - removed impl: getOffscreenContextPixelDataType()
  - removed impl: getOffscreenContextReadBuffer()
  - removed impl: offscreenImageNeedsVerticalFlip()

- Add GLFBODrawable API entries for multi buffering (no impl. yet);
  - TODO: Add implementation code in GLFBODrawableImpl

- GLJPanel 1st simplification using FBO
  - Use above new GL/GLContext entries
  - Fix: getNativeSurface() and getHandle()
  - TODO:
    - Remove distinction of 'pbuffer' and 'software',
    - Use GLDrawableFactory.createOffscreenDrawable(..)
    - Use GL for FBO swapping

4 files changed, 75 insertions, 8 deletions

diff --git a/src/jogl/classes/javax/media/opengl/GLBase.java b/src/jogl/classes/javax/media/opengl/GLBase.java
index 9bcee819a..82bb06b9c 100644
--- a/src/jogl/classes/javax/media/opengl/GLBase.java
+++ b/src/jogl/classes/javax/media/opengl/GLBase.java
@@ -432,6 +432,19 @@ public interface GLBase {
     * </p> 
     */
    public int getDefaultReadFramebuffer();
-
+   
+   /** 
+    * Returns the default color buffer within the current bound 
+    * {@link #getDefaultReadFramebuffer()}, i.e. GL_READ_FRAMEBUFFER​,  
+    * which will be used as the source for pixel reading commands, 
+    * like {@link GL#glReadPixels(int, int, int, int, int, int, java.nio.Buffer)} etc.
+    * <p>
+    * For offscreen framebuffer objects this is {@link GL#GL_COLOR_ATTACHMENT0},
+    * otherwise this is {@link GL#GL_FRONT} for single buffer configurations 
+    * and {@link GL#GL_BACK} for double buffer configurations.
+    * </p> 
+    */
+   public int getDefaultReadBuffer();
+   
 }
 
diff --git a/src/jogl/classes/javax/media/opengl/GLContext.java b/src/jogl/classes/javax/media/opengl/GLContext.java
index de10a2815..235003c38 100644
--- a/src/jogl/classes/javax/media/opengl/GLContext.java
+++ b/src/jogl/classes/javax/media/opengl/GLContext.java
@@ -970,6 +970,32 @@ public abstract class GLContext {
    */
   public abstract int getDefaultReadFramebuffer();
   
+  /** 
+   * Returns the default color buffer within the current bound 
+   * {@link #getDefaultReadFramebuffer()}, i.e. GL_READ_FRAMEBUFFER​,  
+   * which will be used as the source for pixel reading commands, 
+   * like {@link GL#glReadPixels(int, int, int, int, int, int, java.nio.Buffer)} etc.
+   * <p>
+   * For offscreen framebuffer objects this is {@link GL#GL_COLOR_ATTACHMENT0},
+   * otherwise this is {@link GL#GL_FRONT} for single buffer configurations 
+   * and {@link GL#GL_BACK} for double buffer configurations.
+   * </p> 
+   */
+  public abstract int getDefaultReadBuffer();
+  
+  /** On some platforms the mismatch between OpenGL's coordinate
+      system (origin at bottom left) and the window system's
+      coordinate system (origin at top left) necessitates a vertical
+      flip of pixels read from offscreen contexts.
+      <p>
+      Default impl. is <code>true</code>.
+      </p> 
+   */
+  public abstract boolean isGLOrientationFlippedVertical();
+  
+  /** Get the default pixel data type, as required by e.g. {@link GL#glReadPixels(int, int, int, int, int, int, java.nio.Buffer)}. */
+  public abstract int getDefaultPixelDataType();
+  
   /**
    * @return The extension implementing the GLDebugOutput feature,
    *         either <i>GL_ARB_debug_output</i> or <i>GL_AMD_debug_output</i>.
diff --git a/src/jogl/classes/javax/media/opengl/GLFBODrawable.java b/src/jogl/classes/javax/media/opengl/GLFBODrawable.java
index 079d9af5c..4d6c7c20e 100644
--- a/src/jogl/classes/javax/media/opengl/GLFBODrawable.java
+++ b/src/jogl/classes/javax/media/opengl/GLFBODrawable.java
@@ -101,7 +101,8 @@ public interface GLFBODrawable extends GLDrawable {
     void setTextureUnit(int unit);
     
     /**
-     * Set a new sample size
+     * Set the number of sample buffers if using MSAA
+     * 
      * @param gl GL context object bound to this drawable, will be made current during operation. 
      *           A prev. current context will be make current after operation. 
      * @param newSamples new sample size
@@ -113,6 +114,25 @@ public interface GLFBODrawable extends GLDrawable {
      * @return the number of sample buffers if using MSAA, otherwise 0
      */
     int getNumSamples();
+        
+    /**
+     * Sets the number of buffers (FBO) being used if using {@link GLCapabilities#getDoubleBuffered() double buffering}.
+     * <p>
+     * If {@link GLCapabilities#getDoubleBuffered() double buffering} is not chosen, this is a NOP.
+     * </p>
+     * <p>
+     * Must be called before {@link #isInitialized() initialization}, otherwise an exception is thrown.
+     * </p>
+     * @return the new number of buffers (FBO) used, maybe different than the requested <code>bufferCount</code> (see above) 
+     * @throws GLException if already initialized, see {@link #isInitialized()}.
+     */
+    int setNumBuffers(int bufferCount) throws GLException;
+    
+    /** 
+     * @return the number of buffers (FBO) being used. 1 if not using {@link GLCapabilities#getDoubleBuffered() double buffering},
+     * otherwise &ge; 2, depending on {@link #setNumBuffers(int)}. 
+     */
+    int getNumBuffers();
     
     /**
      * @return the used {@link DoubleBufferMode} 
diff --git a/src/jogl/classes/javax/media/opengl/awt/GLJPanel.java b/src/jogl/classes/javax/media/opengl/awt/GLJPanel.java
index dcfc1f0dd..a9d4989dc 100644
--- a/src/jogl/classes/javax/media/opengl/awt/GLJPanel.java
+++ b/src/jogl/classes/javax/media/opengl/awt/GLJPanel.java
@@ -618,12 +618,18 @@ public class GLJPanel extends JPanel implements AWTGLAutoDrawable, WindowClosing
 
   @Override
   public NativeSurface getNativeSurface() {
-    throw new GLException("FIXME");
+    if(null != backend) {
+        return backend.getDrawable().getNativeSurface();
+    }
+    return null;
   }
 
   @Override
   public long getHandle() {
-    throw new GLException("FIXME");
+    if(null != backend) {
+        return backend.getDrawable().getNativeSurface().getSurfaceHandle();
+    }
+    return 0;
   }
 
   @Override
@@ -657,6 +663,8 @@ public class GLJPanel extends JPanel implements AWTGLAutoDrawable, WindowClosing
         if (oglPipelineEnabled) {
           backend = new J2DOGLBackend();
         } else {
+          backend = new SoftwareBackend();
+          /**
           if (!hardwareAccelerationDisabled &&
               factory.canCreateGLPbuffer(null)) {
             backend = new PbufferBackend();
@@ -665,7 +673,7 @@ public class GLJPanel extends JPanel implements AWTGLAutoDrawable, WindowClosing
               throw new GLException("Fallback to software rendering disabled by user");
             }
             backend = new SoftwareBackend();
-          }
+          } */
         }
       }
 
@@ -996,7 +1004,7 @@ public class GLJPanel extends JPanel implements AWTGLAutoDrawable, WindowClosing
           gl.glPixelStorei(GL2.GL_PACK_ALIGNMENT,     1);
 
           // Actually read the pixels.
-          gl.glReadBuffer(GL2.GL_FRONT);
+          gl.glReadBuffer(gl.getDefaultReadBuffer());
           if (readBackBytes != null) {
             gl.glReadPixels(0, 0, readBackWidthInPixels, readBackHeightInPixels, glFormat, glType, readBackBytes);
           } else if (readBackInts != null) {
@@ -1173,12 +1181,12 @@ public class GLJPanel extends JPanel implements AWTGLAutoDrawable, WindowClosing
 
     @Override
     protected int getGLPixelType() {
-      return offscreenContext.getOffscreenContextPixelDataType();
+      return offscreenContext.getDefaultPixelDataType();
     }
 
     @Override
     protected boolean flipVertically() {
-      return offscreenContext.offscreenImageNeedsVerticalFlip();
+      return offscreenContext.isGLOrientationFlippedVertical();
     }
   }