diff options
author | Kenneth Russel <[email protected]> | 2005-04-24 22:59:51 +0000 |
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committer | Kenneth Russel <[email protected]> | 2005-04-24 22:59:51 +0000 |
commit | 492f117fd3f76c7a5778ca2a07c6f5803242b8e0 (patch) | |
tree | bebfe51a2cb8fc36613cdd8ad6caf04b88d1ef47 /doc/userguide/index.html | |
parent | c35019b5256ca33fb642d54608101ab7292f3c60 (diff) |
Merged with current JOGL trunk (by using -r HEAD)
git-svn-id: file:///usr/local/projects/SUN/JOGL/git-svn/svn-server-sync/jogl/branches/JSR-231@262 232f8b59-042b-4e1e-8c03-345bb8c30851
Diffstat (limited to 'doc/userguide/index.html')
-rw-r--r-- | doc/userguide/index.html | 113 |
1 files changed, 63 insertions, 50 deletions
diff --git a/doc/userguide/index.html b/doc/userguide/index.html index 63e622f1a..d9468ea6d 100644 --- a/doc/userguide/index.html +++ b/doc/userguide/index.html @@ -164,17 +164,28 @@ begins to perform rendering. </P> <P> -The <CODE>init()</CODE> method is called once, upon context -creation. (Hooks for context destruction, and support for context -recreation, are not yet implemented.) The <CODE>display()</CODE> -method is called to perform per-frame rendering. The -<CODE>reshape()</CODE> method is called when the drawable has been -resized; the default implementation automatically resizes the OpenGL -viewport so often it is not necessary to do any work in this method. -The <CODE>displayChanged()</CODE> method is designed to allow -applications to support on-the-fly screen mode switching, but support -for this is not yet implemented so the body of this method should -remain empty. +The <CODE>init()</CODE> method is called upon OpenGL context creation. +Any display lists or textures used during the application's normal +rendering loop can be safely initialized in <CODE>init()</CODE>. +Because the underlying AWT window may be destroyed and recreated while +using the same GLCanvas and GLEventListener, the GLEventListener's +<CODE>init()</CODE> method may be called more than once during the +lifetime of the application. It is the responsibility of the +application to understand its sharing of textures and display lists +between multiple OpenGL contexts and reinitialize them when the +<CODE>init()</CODE> callback is entered if necessary. + +</P> +<P> + +The <CODE>display()</CODE> method is called to perform per-frame +rendering. The <CODE>reshape()</CODE> method is called when the +drawable has been resized; the default implementation automatically +resizes the OpenGL viewport so often it is not necessary to do any +work in this method. The <CODE>displayChanged()</CODE> method is +designed to allow applications to support on-the-fly screen mode +switching, but support for this is not yet implemented so the body of +this method should remain empty. </P> <P> @@ -311,44 +322,54 @@ date. </P> <P> -In addition to correctness issues, there are also performance issues -to consider with multithreaded OpenGL applications. The OpenGL context -associated with a particular drawable can only be current on one -thread at a time. If multiple threads may be making the context -current then this implies that the context must be made current and -freed during each render; the overhead of these context operations may -be significant depending on the application. For this reason Jogl has -a built-in mechanism for optimizing the OpenGL context handling to the -efficiency of an analogous C application. +Prior to JOGL 1.1 b10, the JOGL library attempted to give applications +strict control over which thread or threads performed OpenGL +rendering. The <CODE>setRenderingThread()</CODE>, +<CODE>setNoAutoRedrawMode()</CODE> and <CODE>display()</CODE> APIs +were originally designed to allow the application to create its own +animation thread and avoid OpenGL context switching on platforms that +supported it. Unfortunately, serious stability issues caused by +multithreading bugs in either vendors' OpenGL drivers or in the Java +platform implementation have arisen on three of JOGL's major supported +platforms: Windows, Linux and Mac OS X. A detailed description of +these issues can be found on <a +href="http://www.javagaming.org/cgi-bin/JGNetForums/YaBB.cgi?board=jogl;action=display;num=1109286717">this +thread</a> in the <a +href="http://www.javagaming.org/cgi-bin/JGNetForums/YaBB.cgi?board=jogl">JOGL +forums</a>. In order to address these bugs, the threading model in +JOGL 1.1 b10 and later has changed. </P> <P> -<CODE>GLDrawable.setRenderingThread</CODE> informs the Jogl library -that rendering to a particular drawable will only occur from the -specified thread. The intent is that the OpenGL context can be made -current and remain current on that thread until -setRenderingThread(null) is called. Unfortunately, due to -quality-of-implementation bugs in the X11 JAWT, this optimization had -to be made advisory; in other words, it was not possible to guarantee -that setRenderingThread would yield any faster OpenGL context handling -on these platforms. +All GLEventListener callbacks and other internal OpenGL context +management are now performed on one thread: the AWT event queue +thread. This is a thread internal to the implementation of the AWT and +is always present when the AWT is being used. When the +<CODE>GLDrawable.display()</CODE> method is called from user code, it +now performs the work synchronously on the AWT event queue thread, +even if the calling thread is a different thread. The +<CODE>setRenderingThread()</CODE> optimization is now a no-op. The +<CODE>setNoAutoRedraw()</CODE> API still works as previously +advertised, though now that all work is done on the AWT event queue +thread it no longer needs to be used in most cases. (It was previously +useful for working around certain kinds of OpenGL driver bugs.) </P> <P> -In some situations, typically when an application is using pbuffers to -compute intermediate results, it is required that automatic redraws be -suspended for a particular drawable so that the application can -completely control when and where the display() method is called. For -this reason the <CODE>GLDrawable.setNoAutoRedrawMode()</CODE> method -was added; it is used not only by the Jogl implementation but also by -utility libraries such as gleem (included in the jogl-demos -distribution). We consider it unfortunate that it was necessary to -expose two APIs to express basically the same idea and hope that if -the JAWT implementation in the 1.5 platform has better locking -behavior that <CODE>GLDrawable.setNoAutoRedrawMode()</CODE> may be -able to be removed. +Most JOGL applications will not see a change in behavior from this +change in the JOGL implementation. Applications which use thread-local +storage or complex multithreading and synchronization may see a change +in their control flow requiring code changes. While it is strongly +recommended to change such applications to work under the new +threading model, the old threading model can be used by specifying the +system property <CODE>-Djogl.1thread=auto</CODE> or +<CODE>-Djogl.1thread=false</CODE>. The "auto" setting is equivalent to +the behavior in 1.1 b09 and before, where on ATI cards the +single-threaded mode would be used. The "false' setting is equivalent +to disabling the single-threaded mode. "true" is now the default +setting. </P> @@ -409,13 +430,7 @@ The following issues, among others, are outstanding on all platforms: <UL> -<LI> The DefaultGLCapabilitiesChooser tends to choose the wrong visual -on lower-end graphics cards. - -<LI> Hardware acceleration for GLJPanel could be implemented using -pbuffers. - -<LI> Stability issues, in particular on older graphics cards. +<LI> A few remaining stability issues, mostly on older graphics cards. </UL> @@ -471,8 +486,6 @@ The following issues remain with the Mac OS X port: <UL> -<LI> GLJPanel is not yet implemented on Mac OS X. - <LI> Due to the mechanism by which the Cocoa graphics system selects OpenGL pixel formats, the GLCapabilitiesChooser mechanism can not be implemented on Mac OS X as on other platforms. In the future, the |