Bug 1020 - First MSAA FBO frame on a mac osx nvidia card not antialiased

OSX/Nvidia's FBO needs to be cleared before blitting,
otherwise first MSAA frame lacks antialiasing.

GLFBODrawableImpl.initialize(..) can clear
GL.GL_COLOR_BUFFER_BIT and GL.GL_DEPTH_BUFFER_BIT, if used.

FBObject cannot clear the buffer(s) due to it's low-level API,
i.e. it cannot know when the first bind occurs _after_ user
completed FBO setup (attaching buffers).

Hence plain FBObject usage required manual injection
of glClear(..) after setup as demonstrated in GLJPanel.

We may need to elaborate in this case,
i.e. add an FBObject API entry like 'fbo.postInitNotify()'.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/jogl/classes/javax/media/opengl/awt/GLJPanel.java b/src/jogl/classes/javax/media/opengl/awt/GLJPanel.java
index e2ccc1097..cfb11a2b0 100644
--- a/src/jogl/classes/javax/media/opengl/awt/GLJPanel.java
+++ b/src/jogl/classes/javax/media/opengl/awt/GLJPanel.java
@@ -1636,6 +1636,11 @@ public class GLJPanel extends JPanel implements AWTGLAutoDrawable, WindowClosing
               helper.setAutoSwapBufferMode(false); // we handle swap-buffers, see handlesSwapBuffer()
 
               final GL gl = offscreenContext.getGL();
+              // Remedy for Bug 1020, i.e. OSX/Nvidia's FBO needs to be cleared before blitting,
+              // otherwise first MSAA frame lacks antialiasing.
+              // Clearing of FBO is performed within GLFBODrawableImpl.initialize(..):
+              //   gl.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT);
+
               final GLCapabilitiesImmutable chosenCaps = offscreenDrawable.getChosenGLCapabilities();
               final boolean glslCompliant = !offscreenContext.hasRendererQuirk(GLRendererQuirks.GLSLNonCompliant);
               final boolean useGLSLFlip = useGLSLFlip_pre && gl.isGL2ES2() && glslCompliant;
@@ -1653,6 +1658,7 @@ public class GLJPanel extends JPanel implements AWTGLAutoDrawable, WindowClosing
                       fboFlipped.reset(gl, fboDrawable.getSurfaceWidth(), fboDrawable.getSurfaceHeight(), 0, false);
                       fboFlipped.attachColorbuffer(gl, 0, chosenCaps.getAlphaBits()>0);
                       // fboFlipped.attachRenderbuffer(gl, Attachment.Type.DEPTH, 24);
+                      gl.glClear(GL.GL_COLOR_BUFFER_BIT); // Bug 1020 (see above), cannot do in FBObject due to unknown 'first bind' state.
                       glslTextureRaster = new GLSLTextureRaster(fboDrawable.getTextureUnit(), true);
                       glslTextureRaster.init(gl.getGL2ES2());
                       glslTextureRaster.reshape(gl.getGL2ES2(), 0, 0, fboDrawable.getSurfaceWidth(), fboDrawable.getSurfaceHeight());