Hello,
just curious, why would you want to draw translucent images
directly to the screen?
Drawing translucent images to an opaque window sounds
strange to me. Wouldn't you get artifacts with partial
repaints and stuff? If you do clear the window before
rendering your image, then it's no different from
just rendering to an opaque image filled with the background
color.
Typically one would have an opaque back buffer, and render
everything into there, then present it. It is highly recommended
to use the BufferStrategy API for your double-buffering
implementation.
Another questions is which java version have you tried?
Have you tried 6uN (dev. builds available at http://jdk6.dev.java.net)
[EMAIL PROTECTED] wrote:
I'm having some serious trouble with the performance of alpha blending in Java
-- so serious that I suspect that I'm doing something wrong. I don't know what
I'm doing wrong, though, so I'm hoping someone might be able to tell me. Here
follows the results of some experiments I've been doing.
First of all, I'm trying to draw BufferedImages with an alpha channel directly
onto a window. I'm using Java 1.6 all the time. I'm trying to draw a number of
50x50 images onto the window at 16 FPS, and performance seems to scale linearly
with around 6% CPU per images (so at 4 images, it consumes ~24% CPU, at 8
images ~50% CPU, and at around 15 or more images the framerate starts to drop).
I also tried to draw one 800x600 image onto a window, and it takes around 400
ms. Performance in this test seems to be about the same on both Linux and
Windows, by the way.
Yeah, that wouldn't work too well.
Second, I'm trying to use VolatileImages to draw the images onto the window
(using GraphicsConfiguration.createCompatibleVolatileImage()). However, that
doesn't work at all, because Java2D will only give me opaque VolatileImages. It
doesn't return VolatileImages with either 1-bit or alpha transparency, on
either Linux or Windows. It may be worth mentioning that I have direct
rendering working on the Linux system.
Translucent VIs are only available with opengl pipeline
(since 1.5, and depending on your configuration) and the new
d3d pipeline in 6uN.
Third, I tried to use the Direct3D rendering pipeline by setting
sun.java2d.d3d=true. That actually works fairly well, and I seem to be able to
draw alpha transparent images at about the same rate as normal images, and
opaque images are drawn faster as well. However, it obviously only works on
Windows, so I'd very much prefer not use it. A weird thing I noticed is that I
still don't get accelerated VolatileImages for translucent images. Should it be
like that?
Yeah, see above. The new d3d pipeline is enabled by default, and
it does support accelerated translucent VIs.
Fourth, I tried to use the OpenGL rendering pipeline by setting
sun.java2d.opengl=true, which is a very mixed blessing. because performance
became definitely wonderful on Windows. All draw operations dropped to hardly
measurable times. However, it doesn't seem to work at all on Linux, because
performance wasn't affected at atll, and when setting sun.java2d.trace=count,
it indicates that it's still using the normal XPM drawing routines. There also
seems to be a fairly serious bug when using it on Windows, because when drawing
newly created BufferedImages, the result is some weird monochrome blue drawing.
As long as the BufferedImages weren't created recently, they are drawn as they
should. Am I doing something weird to cause this behavior? Oh, and by the way,
I'm still not getting accelerated VolatileImages, which I find weird.
What is your video board? Could you please provide output with
J2D_TRACE_LEVEL=4 env. variable set?
If you try the 6uN build, could you please provide output
from that as well (on windows, too).
Also, I'm wondering about the usage of the alternate pipelines as such. It
seems to be working fairly OK for stand-alone programs, but what about applets?
Is it at all possible to use the alternate pipelines when writing an applet?
Even if I can somehow get permission to change system properties within an
applet, AWT has already been started and set up its pipelines by that time,
right?
[Message sent by forum member 'dolda2000' (dolda2000)]
With the new Java plugin in 6u10 you will be able to specify
vm parameters (and a separate vm will be started).
Although I would suggest against enabling the
opengl pipeline unconditionally. It could be better to provide
separate links for "accelerated" and sw-rendering.
The new d3d pipeline is enabled by default, so you don't need
to provide any flags.
Thanks,
Dmitri
Java2D Team
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