The exporter really isn't as bad as people make it out. It has never
failed me excepting a few manual fixes for texture paths. It seems to
me that most people's problems stem from an uncertainty about
Blender's operation. I've been using blender for about 5/6 years now,
and the osg exporter for maybe two. I've exported textured,
untextured, material-ed, no material-ed, vertex colours, no vertex
colours, .osg files up to 500mb using just about every combination of
everything. A few spurious material nodes and incomplete textures
paths really is the worst I've seen. Script has never failed me.
If you're exporting a model for realtime 3D Ben's "technique C" is
the only valid one. The other "texturing techniques" are used for
Blender's raytracer. If you want to put multiple textures on a mesh,
split the mesh into multiple objects and texture them individually.
There are other ways to assign up to 16(?) textures to a mesh with a
per-face granularity, but the Blender->osg exporter does not support
this.
Blender's not an easy tool to come to grips with, it takes a lot of
time, patience and experimentation to find out what all the buttons
do, but once you've noticed the pattern, the "modal" editing system
is quite elegant and logical.
Alan.
On 21 Aug 2006, at 06:39, Ben Discoe wrote:
-----
From: Alan Purvis
Sent: Sunday, August 20, 2006 12:53 PM
the button(s) you pushed in Blender.
Press alt-z with the cursor over the 3D view.
Aaaaaah! Thank you Alan. This opens the window on a whole new
understanding of Blender's texture handling. Apparently, there are
three
different ways to put a texture on something in Blender:
A. Assign a textured material to an object.
B. Assign a textured material to a mesh, or part of a mesh.
C. Somehow vaguely associate a texture with an object, using the
"UV Face
Select" + "UV Editor" + "Image Open."
Amazingly, only this option C has any consistent effect on what gets
exported, to either the .osg or .dae formats. It also has the most
effect
on what is shown in Alt-Z rendering mode. To make things worse,
Blender
actually lets you do (A/B) and (C) at the same time, so an object
can have
multiple, conflicting textures!
Jan gives a good description of this confusing, unlikely and
undocumented
way of applying a texture:
From: Jan Ciger
Sent: Sunday, August 20, 2006 1:55 PM
Select the object you want to map the
texture to (in object mode), switch to UV mapping mode. In
the UV editor you should see the object unwrapped. Select all
faces (hit 'A'). Then I have just changed the image file
using the list box in the UV editor to show the correct image
and that's it. The same for the other object.
Yow. Yes, it's almost usable... once you know it.
When you render them in OSG, the poles do not even appear.
I see the poles just fine as red.
I am sorry, i can't see how it is "just fine" that the poles are
textured
(either transparent or red) since 1. The poles aren't textured and
2. They
have a grey material on them. Red is a big bug.
The problem lies in bogus texture coordinates for the poles:
5.6051938573e-45 1.12103877146e-44 - all the texture
coordinates on the poles are like this - invalid.
The problem is bigger: the fact that both texture, and texture
coordinates,
are written at all, for an object that has _no_ texture
coordinates, or
texture, in the Blender scene. Remember i pointed out the failure
in your
.osg output:
name "Pole2"
Geode {
StateSet {
textureUnit 0 {
Texture2D {
file "stop128.png"
The 'pole' objects do not have any texture, not by method (A) (B)
or (C)
above. If Blender + exporter can't write an untextured object as
untextured, then it's really not a usable art path.
Roger wrote:
This observation is not in any way a criticism of this code, it is
open source so you either work within the boundaries of what someone
else has written or get your hands dirty!
Yes. The question becomes - is it even possible to fix/workaround in
osgexport? I will try. Or do we have to join the Blender coding
team to
fix it from that side?
Jan writes:
BTW, did you see some of the exporters available for 3DS Max or Maya?
That is sometimes black magic and complete voodoo to get to work
right
Unfortunately i know exactly what you're talking about. It's only
after
years of holding out hope for MAX+various exporters, including
OSGExp, that
i finally gave up on that broken mess and tried Blender+osgexport,
in hopes
it would be more straightforward and functional :)
Thanks,
Ben
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