Re: [JAVA3D] Strange rendering issues (Now with _real_ attachments)

[�yvind Andersen]

Title: Strange rendering issues (Now with _real_ attachments)

Cool effects, aye, but it looks a lot nicer now that they're gone :-)

 

Turning double-sided polygons _off_ actually helped quite a bit (maybe that's what you meant anyway). I also changed the front and back clipping planes to a tighter fit around the model and forced a 24-bit depth buffer in the initialization of the canvas3d. The latter two measures helped, but the first one seems to have made most of the difference and prompted a bit of forehead-slapping on my part :-). Double sided polygons might be a good idea early in debugging, but should really be turned off later if they aren't needed

 

The numbers involved were intentionally omitted because I have tested several sets and they all produced the same results. However, both the inner diameter and the thickness of the semi-cylinder are a lot smaller than its length so your assessment of the problem is probably correct. I suspected the z-buffer was somehow involved, but couldn't figure out how. Thanks a lot for your help!

 

�yvind Andersen

 

 

 -----Original Message-----
From: Florin Herinean [mailto:[EMAIL PROTECTED]
Sent: 10. mars 2004 11:00
To: [EMAIL PROTECTED]
Subject: Re: [JAVA3D] Strange rendering issues (Now with _real_ attachments)

Cool efects ! ;-)

 

What happens if you turn double sided polygons on ? If then your image looks ok, it's most probable that you're having problems with the graphic card zbuffer resolution, i.e. front polygons and back polygons just have the same integer "z", and it's possible that the engine will draw the logically far polygons which are backfacing.

 

However, you should give us some numbers: size of the semicilinder, the width, back and front clipping planes, etc., or better post the model here. Just from the picture it's difficult to realize what can be the cause.

 

Cheers,

 

Florin

-----Original Message-----
From: Discussion list for Java 3D API [mailto:[EMAIL PROTECTED]On Behalf Of �yvind Andersen
Sent: Mittwoch, 10. M�rz 2004 10:31
To: [EMAIL PROTECTED]
Subject: [JAVA3D] Strange rendering issues (Now with _real_ attachments)

Hello

Attached is a couple of screenshots of an object viewed from different positions, one very close to it and the other a bit further away. As you can see viewing the object from some distance produces some weird and unpleasant looking "holes". The object is a TriangleArray with a material, the lightsource is a directionallight attached to the viewplatform (headlight). The front- and backclip distances are within the limits proposed in the javadocs. I'm running java3d 1.3.1 OpenGL version on a GeForce4 graphics card with recently updated drivers.

Some interesting points: when substituting the material with coloringattributes the object renders just fine, but that will not do for my application, I need materials and lighting. Increasing the frontclip distance and decreasing the backclip distance alleviates the problem a little bit, but does not remove it. It just means the holes disappear marginally earlier when moving closer. The objects normals are generated by a NormalGenerator and looks slightly off in places, but nothing major.

All help, insight or pure speculation on this subject will be greatly appreciated.

�yvind Andersen

P.S. Forgot the attachments last time. Sorry

<<ss_close.jpg>> <<ss_far.jpg>>

=========================================================================== To unsubscribe, send email to [EMAIL PROTECTED] and include in the body of the message "signoff JAVA3D-INTEREST". For general help, send email to [EMAIL PROTECTED] and include in the body of the message "help".

=========================================================================== To unsubscribe, send email to [EMAIL PROTECTED] and include in the body of the message "signoff JAVA3D-INTEREST". For general help, send email to [EMAIL PROTECTED] and include in the body of the message "help".

=========================================================================== To unsubscribe, send email to [EMAIL PROTECTED] and include in the body of the message "signoff JAVA3D-INTEREST". For general help, send email to [EMAIL PROTECTED] and include in the body of the message "help".