Hi Roy,
Bug 4640525 -
Alpha of color vertex did not update correctly for blending mode
is submitted for investigation. Looks like every time a vertex
is add, we multiple the whole geometryArray color vertex
by alpha instead of just one vertex. Thus the value
accumulate and we got this nice fading effect automatically.
Under Solaris, OpenGL extension GL_SUN_global_alpha
is used so there is no need to set color vertex alpha
value explicitly.
Thanks for your bug report.
- Kelvin
--------------------
Java 3D Team
Sun Microsystems Inc.
>X-Unix-From: [EMAIL PROTECTED] Tue Feb 19 14:59:39 2002
>Date: Tue, 19 Feb 2002 17:58:23 -0500
>From: Roy Duffy <[EMAIL PROTECTED]>
>Subject: [JAVA3D] transparency bug??
>To: [EMAIL PROTECTED]
>MIME-version: 1.0
>X-Accept-Language: en
>Delivered-to: [EMAIL PROTECTED]
>
>I think I may have found a bug in Java3D 1.3 beta1.
>I've attached a small program that adds points to a LineStripArray to
>make it form a circular path. When it adds a new point, it increments
>the line's visible length by calling setStripVertexCounts(). It also
>sets the color of the vertex to a fixed color value (white).
>I gave it a BLENDED TransparencyAttributes object with a blend value of
>0.025, which should make the entire line almost completely opaque. But
>when I run the program, the line starts out opaque, but then fades away
>to nothing. If I don't set the color of every vertex, the transparency
>works fine. Or if I use SCREEN_DOOR instead of BLENDED, it's also
>fine. I also get the same result if I use a TriangleStripArray instead
>of a LineStripArray.
>I'm using JDK1.4 with OpenGL Java3D 1.3 beta1 and running on WinNT with
>an NVidia Gladiac GeForce2 Ultra card.
>I tried this on a Sun Ultra 10 with Solaris 8 and the problem didn't
>occur, so that leads me to believe it's either the Windows version of
>Java3D or a problem with my graphics card. I don't have any other PC
>cards to test it on.
>Has anyone noticed this before?
>
> -Roy Duffy
>[EMAIL PROTECTED]
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