Hi Carsten,
first off, my understanding is that the TransparencyForceTransparent,
... give you the possibility to govern the process of transparency
detection of a material. If you have a standard material this can be
done automatically and therefore the default for the attribute is
TransparencyAutoDetection. However, if you have a fancy material as in
my case that does not have any known transparency characteristic you
need to have a way to tell the system that your material is either
transparent or opaque. At least that is my interpetration :-)
See the ChunkMaterial::isTransparent() implementation:
bool ChunkMaterial::isTransparent(void) const
{
Int32 tm = getTransparencyMode();
if(tm != Material::TransparencyAutoDetection)
{
return (tm == Material::TransparencyForceTransparent);
}
bool returnValue = false;
MFChunksType::const_iterator chunksIt = _mfChunks.begin();
MFChunksType::const_iterator chunksEnd = _mfChunks.end ();
for(; chunksIt != chunksEnd && returnValue == false; ++chunksIt)
{
returnValue = (*chunksIt)->isTransparent();
}
return returnValue;
}
Next, I know that you haven't written the DepthPeelingStage. What I
hoped to learn, is the 'correct' way of writing any Stage with respect
to transparency. If have debugged a little in the stage and see that in
a mixed transparency/opaque scene the rooted stage's renderEnter(Action*
action) method is called exactly once. That mean (correct my if I'm
wrong) that the stage is responsible for discriminating the transparent
from the opaque pass. For instance in the case of shadowing, the
transparent geometry should not be part of the shadow map generating
objects at all, because they do not cast any shadows. So part of a
shadow stage must be able to constrain on opaque geometries. Or in the
depth peeling case the opaque geometry must be rendered with other
materials and possibly other shader configuration. So there must be a
way to detect the render state in the shader.
I'm looking for explanation of how these things are to be set up
correctly in any Stage implementation. I think that this is a central
point and I would like to learn these details in order to do my thinks
correctly.
On 08.03.2017 17:02, Carsten Neumann wrote:
>
>> Is it even possible to mix opaque and transparent geometry with the
>> DepthPeelingStage core or is the stage incomplete with respect to that task?
>
> I guess that is a possibility.
>
In that case it needs correction to be usable in the common case.
>
> Transparent objects are rendered after opaque ones in back to front
> order (IIRC using the bounding box center).
>
Yes, but that is not enough in my understanding. There has to be a
pattern of how to write Stages with respect to transparency in the case
that different rendering setups are necessary for transparent and opaque
geometries.
>> Could you please take a look into the example and give me some hint what
>> I'm doing wrong here?
>
> Not specifically, sorry. In general I would suspect it has something to
> do with the FBOs/Attachments the stages are rendering into and how they
> perform clearing.
I will have a look into the details.
I really need more explanations for the RenderAction, RenderPartition,
Stage, transparency mix. I have searched the mailing list but did not
get enough information for sorting the issues in my head.
Be patient with me :-)
Best,
Johannes
------------------------------------------------------------------------------
Announcing the Oxford Dictionaries API! The API offers world-renowned
dictionary content that is easy and intuitive to access. Sign up for an
account today to start using our lexical data to power your apps and
projects. Get started today and enter our developer competition.
http://sdm.link/oxford
_______________________________________________
Opensg-users mailing list
Opensg-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/opensg-users
