Even within the transparent bin you can enforce specific ordering with
the bin number. Lower numbers get rendered before higher numbers.
I'd have to dig to find any of my own example code but I hoped perhaps
the hint would be enough in short time.
We did this all the time to render double-side transparent geometry.
Draw the inner faces in a lower bin number than the outer faces. Even
with different bin numbers you can still depth sort them.
We had semi-transparent glass boxes with text on the sides. I think we
ultimately had three different bin numbers we used for that associated
with the inner, outer, and text geometries.
-Paul
Jason Daly wrote:
Rabbi Robinson wrote:
Hi,
Is there anyway that I can enforce drawing the objects inside first
before drawing the outside membrane?
Sure, just use setRenderBinDetails() to set a render bin for the
membrane that has a higher number than the render bin used by the
interior objects. For the other parameter, you can set either
"DefaultBin" for a state-sorted bin, or "DepthSortedBin" for a
depth-sorted bin.
interiorStateSet->setRenderBinDetails(0, "DefaultBin");
membraneStateSet->setRenderBinDetails(10, "DepthSortedBin");
However, this is equivalent to this code:
interiorStateSet->setRenderingHint(StateSet::OPAQUE_BIN);
membraneStateSet->setRenderingHint(StateSet::TRANSPARENT_BIN);
Which is probably close to what you're already doing. The problem is
that the transparent geometry still has to obey the depth (z-buffer)
test, even if it's drawn last. You can try disabling the depth test,
but this is likely to cause other problems (if you ever have anything
move in front of the membrane, for example):
depth = new Depth();
depth->setFunction(Depth::ALWAYS);
membraneStateSet->setAttributeAndModes(depth, StateAttribute::ON);
This is the main reason why the alpha to coverage method is sometimes
used, even though it's a bit expensive in draw time.
--"J"
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