Hi Paul,
The OSG does nothing to discriminate between geometries based on
transparency, they are treated the same.
As to why you are observing differences I have no clue.
Robert.
On 1/17/07, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
I'm using OSG 1.2 with custom shaders.
I have an object (with transparency of 1.0 but with
"Fixed with Alpha" set in the FLT file) that shows up
several seconds into my simulation. When it shows up,
it appears to take around 200ms to render. It ONLY
takes this long on the initial frame the object is
visible. Subsequent frames render quickly. The object
in question is relatively small (<20 facets) but does
have a relatively complex shader associated with it.
I've tracked the long draw times to the glCallList
call in osg::Drawable::draw(State &state).
If I change the OpenFlight file to have "Fixed with No
Alpha", the speed is acceptable. In particular, the
OSG differences in my object with and without
transparency are as follows:
1471,1474c1471,1472
< rendering_hint TRANSPARENT_BIN
< renderBinMode USE
< binNumber 10
< binName DepthSortedBin
---
> rendering_hint DEFAULT_BIN
> renderBinMode INHERIT
1477d1474
< GL_BLEND ON
1487,1492d1483
< BlendFunc {
< UniqueID BlendFunc_18
< DataVariance STATIC
< source SRC_ALPHA
< destination ONE_MINUS_SRC_ALPHA
< }
I wasn't having this problem previously (I think
previous to 1.2).
Can somebody explain what is going on here? Are
display lists used for alpha-based objects? Why does
it take so long to execute the display list the first
time?
Thanks,
Paul
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