Yes, I do know that there is a change of textures going on when you rotate
the volume, but this is not the flip that i am talking about. The flip
that i am talking about does not happen if you don't enable YUP. Just try
out the original program unchanged ... you should not see the volume
flipping. Again, yes there is a change of textures depending on the
viewpoint, but the flip that i am talking about actually changes the UV
orientation of the textures. This flip should be more clear if you try
loading a non-symmetric volume in the unchanged and then in the changed
program.
b.t.w.:I am currently running it on a pc (windows NT)
nader
On Thu, 26 Apr 2001 15:42:17 +0200, Dipl. Ing. Paul Szawlowski
<[EMAIL PROTECTED]> wrote:
>If you look a the code you will recognize that the volume data will be
put as
>textures on planes parallel to the x-y, y-z and x-z planes. Depending on
your
>viewpoint the textures will be showed along the x, y, or z axes using the
>planes parallel to the y-z, x-z or x-y planes respectively. The change of
axes
>when your viewpoint changes is what you describe as flip. You can see the
>difference how the image is rendered if you uncheck the double buffer
checkbox.
>So there is no bug in the code, it's just an effect of this volume
rendering
>method.
>
>regards
>Paul
>
>
Hi,
I have been trying out Doug Gehringer's Volume Rendering app. (available
from j3d.org) and have noticed this peculiar misbehavior. What I noticed
is that YUP only works for the textures along the z-axis but not the
x-axis nor the y-axis. I thought it was a bug in the code but could not
resolve it. To try to track it down, I even changed the order in which
the textures are generated and displayed, but that did not change things:
the z-textures where displayed correctly as YUP, but the the other axis
textures where displayed upsided down; this is apparent by the flip of the
voxels when the volume is rotated.
To see this for yourself, do the following:
1. get Doug Gehringer's Volume rendering app (available from j3d.org)
2. In Texture2DVolume.java, change the following line(s) (approx. line 210
and 226):
pArray = new ImageComponent2D(ImageComponent.FORMAT_RGBA, sSize, tSize);
and
pArray = new ImageComponent2D(ImageComponent.FORMAT_CHANNEL8, sSize,
tSize);
to:
pArray = new ImageComponent2D(ImageComponent.FORMAT_RGBA, sSize,
tSize,false,true /* YUP flag*/);
and
pArray = new ImageComponent2D(ImageComponent.FORMAT_CHANNEL8, sSize,
tSize,false,true /* YUP flag*/);
respectively.
3. build and run it and load the sample 64x64x64 data set; as you rotate
the volume, you will see a sudden jump of the voxels ... this is actually
a flip but do due the symmetry of the data, it just looks like a jump.
I considered that it might have to do with the loading of the textures
from the dataset but the app seems to work fine with YUP being false
(there are no apparent flips) so i ruled that out.
So, if you do this and this is all true, can you please tell me if this is
a bug in the code (and where is it) and if not, is this a YUP bug?
nader
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