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Issue: MultiTexture COMBINE mode & OffScreen snapshot

4 replies [Last post]
nvaidya
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Joined: 2004-08-03
Points: 0

With two TextureUnitStates, tus0 and tus1, with MODULATE and COMBINE texture modes, respectively, an offscreen snapshot fails to show the texture of tus0. If the modes are flipped between tus0 and tus1, then the offscreen snapshot looks correct.

In both cases, the onscreen renderings look correct.

Can get a testcase if needed...

--Vaidya

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kcr
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Joined: 2004-03-17
Points: 0

Sounds like a driver bug. What graphics card are you using? If you could generate a simple test case, maybe others could try it on a different graphics card. If it reproduces on more than one card then it may be a Java 3D bug and we'll take a look at it.

-- Kevin

nvaidya
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Joined: 2004-08-03
Points: 0

Well, have cooked up a simple testcase which you can find here:
http://www.freewebs.com/matspring/issues.htm

The file is called mtexissue.jar. To test do:
1. un-jar the archive
2. grab bg.jpg and stone.jpg from the images sub-directory under the $j2sdkHOME/demo/java3d directory, and place them in mtexissue directory.
3. compile and launch
4. click on the menu-menuitem to grab a snapshot
5. check if there is any difference between onscreen and offscreen renders.

Since you mentioned it could be a driver issue, I immediately downloaded and tested with the nvidia driver 61.77 (thanks to my new broadband) ! still see the same problem. If someone could test with GeForce2 MX/MX 400/ GeForce4 Ti4200, it will be great.

Still waiting to see how the PCI express scene develops.

Thanks

--Vaidya

kcr
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Joined: 2004-03-17
Points: 0

I was able to reproduce this on Windows/XP; it works fine on Linux using the same hardware (with J3D 1.3.1, since all OffScreen rendering on Linux is broken at the moment in 1.3.2).

Btw, on my system the rendering is still wrong when the texture attributes are swapped. It's just more subtle than the original test case (the specular highligts aren't being rendered).

Please file an Issue so we can track it. Thanks.

-- Kevin

nvaidya
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Joined: 2004-08-03
Points: 0

Done...Issue #28.

Muchos Gracias for trying the testcase...thought I was really stuck with a driver issue.

Also, you are very correct about the specular highlights being missing for either one of the combos.

Is the GL_SEPARATE_SPECULAR_COLOR added automatically within Java 3D ? And is that what is missing in the snapshot ?

Funnily, I was exploiting this bug temporarily as a "feature". I wanted to do within a behavior this: 1. take snapshot 2. change Appearance 3. take snapshot again. However, with this issue I could get away by taking a single snapshot :).

Thanks

--Vaidya