Re: [osg-users] Passing location-based data to a fragment shader
Hi Sebastian,
Thanks for the detailed explanation and the hints regarding texture/world
coordinates. I've tried binding at the tile level as you suggested, but
apparently the additional data source is not fast enough to be used at
real-time.
At this point, I'm going to have the original terrain model regenerated with
two textures for each tile, instead of constructing the second texture on the
fly. As far as I understand, binding a second texture should be possible with
the OSG and TXP formats.
So thanks again for attempting to help with issue.
Best,
Shahar
Sebastian Messerschmidt wrote:
You don't really need to bind at a level this deep. Usually if the
terrain tile is loaded and represent a LOD you want to work with, you
can simple add your data texture(s) as uniform to the stateset of the tile.
Given you have a texture with the data-image called texture you can do
it this way in your callback:
osg::StateSet* state_set = node-getOrCreateStateSet();
osg::Uniform* sampler = new osg::Uniform(MyDataSamper, 2
/*texture unit*/);
state_set-setTextureAttribute(unit, texture ,osg::StateAttribute::ON);
state_set-addUniform(sampler);
With this you bind the texture to a sampler for your shader, at the
texture unit 2. Depending on how many textures are already bound you
might need to modify the unit.
In the fragment shader you can now access the texture via:
uniform sampler2D MyDataSampler
..
..
main()
{
vec2 tex_coord = gl_TexCoord[0].st;
vec4 data = texture2D(MyDataSampler, tex_coord);
}
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Re: [osg-users] Passing location-based data to a fragment shader
Hi Nick, Yes, this is part of what I'm trying to do (I'd like to do the same with osg models). I'd be glad if you could elaborate on the different approach, even though I would probably go with pre-generating the texture along with the archive. Thanks, Shahar Trajce Nikolov NICK wrote: Hi Shahar, I read this post and found it interesting. Just out of curiosity : Each texel in the new texture, should be set based on the world location of the corresponding texel in the current geometry texture Are you trying to overlay a texture on top of txp archive and it should be georeferenced? If so, there might be a different approach Nick -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=55009#55009 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Passing location-based data to a fragment shader
Hi Shahar,
I read this post and found it interesting. Just out of curiosity :
Each texel in the new texture, should be set based on the world location of
the corresponding texel in the current geometry texture
Are you trying to overlay a texture on top of txp archive and it should be
georeferenced? If so, there might be a different approach
Nick
On Tue, Jun 25, 2013 at 3:50 PM, Sebastian Messerschmidt
sebastian.messerschm...@gmx.de wrote:
Hi Shahar,
answers below.
Sebastian Messerschmidt wrote:
Hi Shahar Kosti:
As you don't provide any exact numbers I can only guess. But usually I'd
bind one or more textures per tile of paged set.
Depending on your hardware bind of 8192x8192 textures is no problem.
Can you be a bit more specific on how big the set is?
Also for the hidden textures - I don't really get what you mean. My best
guess is, that you mean not displayed.
Therefore write a custom fragment shader and bind the data-textures
along with you diffuse or whatever textures to the stateset of the tile.
As the fragment shader is fully programmable, it is your choice what is
done with the data.
cheers
Sebastian
Hi Sebastian,
Sorry for my late reply, it took me some time to get the data.
One TXP I'm currently looking at, represents a 3000 km² area with texture
resolution of 5m/pixel. Some areas have better resolution, up to 10
cm/pixel. The additional metadata has similar resolution. So obviously
wouldn't fit on a single texture.
Okay, so the single TXP file represents the whole area? That's kinda hard,
I thought you have multiple tiles representing parts of your complete data
set.
Anyways, First of all, your data sets need to be aligned somehow.
Regarding your suggestions, could you elaborate on the bind one or more
textures per tile of paged set approach?
My current approach (which doesn't work), is to intercept paged nodes
using a custom ReadFileCallback, which runs a NodeVisitor. The visitor
finds all Geode objects and then the underlying geometries. I can bind a
new texture to these geometries, but I'm not sure how to set the values
correctly.
You don't really need to bind at a level this deep. Usually if the
terrain tile is loaded and represent a LOD you want to work with, you can
simple add your data texture(s) as uniform to the stateset of the tile.
Given you have a texture with the data-image called texture you can do
it this way in your callback:
osg::StateSet* state_set = node-getOrCreateStateSet();
osg::Uniform* sampler = new osg::Uniform(MyDataSamper, 2 /*texture
unit*/);
state_set-**setTextureAttribute(unit, texture
,osg::StateAttribute::ON);
state_set-addUniform(sampler)**;
With this you bind the texture to a sampler for your shader, at the
texture unit 2. Depending on how many textures are already bound you might
need to modify the unit.
In the fragment shader you can now access the texture via:
uniform sampler2D MyDataSampler
..
..
main()
{
vec2 tex_coord = gl_TexCoord[0].st;
vec4 data = texture2D(MyDataSampler, tex_coord);
}
Each texel in the new texture, should be set based on the world location
of the corresponding texel in the current geometry texture. I'm not sure
how to do that using the geometry vertex and texture coordinate indices.
I hope this is clear enough.
This is a different question. If your terrain-data already contains a base
texture (like a satellite photo), the gl_TexCoord[0] might be matching
already.
If not you might want to use texture coordinate generation in the vertex
shader to get world-space texture coordinates.
It totally depends on your data.
For a first try, I'd load a dummy texture for each tile and pass it to the
gl_FragColor in the fragment shader to see how your coordinates are.
cheers
Sebastian
Thanks for the help,
Shahar
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Re: [osg-users] Passing location-based data to a fragment shader
Hi Shahar,
answers below.
Sebastian Messerschmidt wrote:
Hi Shahar Kosti:
As you don't provide any exact numbers I can only guess. But usually I'd
bind one or more textures per tile of paged set.
Depending on your hardware bind of 8192x8192 textures is no problem.
Can you be a bit more specific on how big the set is?
Also for the hidden textures - I don't really get what you mean. My best
guess is, that you mean not displayed.
Therefore write a custom fragment shader and bind the data-textures
along with you diffuse or whatever textures to the stateset of the tile.
As the fragment shader is fully programmable, it is your choice what is
done with the data.
cheers
Sebastian
Hi Sebastian,
Sorry for my late reply, it took me some time to get the data.
One TXP I'm currently looking at, represents a 3000 km² area with texture
resolution of 5m/pixel. Some areas have better resolution, up to 10 cm/pixel.
The additional metadata has similar resolution. So obviously wouldn't fit on a
single texture.
Okay, so the single TXP file represents the whole area? That's kinda
hard, I thought you have multiple tiles representing parts of your
complete data set.
Anyways, First of all, your data sets need to be aligned somehow.
Regarding your suggestions, could you elaborate on the bind one or more textures
per tile of paged set approach?
My current approach (which doesn't work), is to intercept paged nodes using a
custom ReadFileCallback, which runs a NodeVisitor. The visitor finds all Geode
objects and then the underlying geometries. I can bind a new texture to these
geometries, but I'm not sure how to set the values correctly.
You don't really need to bind at a level this deep. Usually if the
terrain tile is loaded and represent a LOD you want to work with, you
can simple add your data texture(s) as uniform to the stateset of the tile.
Given you have a texture with the data-image called texture you can do
it this way in your callback:
osg::StateSet* state_set = node-getOrCreateStateSet();
osg::Uniform* sampler = new osg::Uniform(MyDataSamper, 2
/*texture unit*/);
state_set-setTextureAttribute(unit, texture ,osg::StateAttribute::ON);
state_set-addUniform(sampler);
With this you bind the texture to a sampler for your shader, at the
texture unit 2. Depending on how many textures are already bound you
might need to modify the unit.
In the fragment shader you can now access the texture via:
uniform sampler2D MyDataSampler
..
..
main()
{
vec2 tex_coord = gl_TexCoord[0].st;
vec4 data = texture2D(MyDataSampler, tex_coord);
}
Each texel in the new texture, should be set based on the world location of the
corresponding texel in the current geometry texture. I'm not sure how to do
that using the geometry vertex and texture coordinate indices.
I hope this is clear enough.
This is a different question. If your terrain-data already contains a
base texture (like a satellite photo), the gl_TexCoord[0] might be
matching already.
If not you might want to use texture coordinate generation in the vertex
shader to get world-space texture coordinates.
It totally depends on your data.
For a first try, I'd load a dummy texture for each tile and pass it to
the gl_FragColor in the fragment shader to see how your coordinates are.
cheers
Sebastian
Thanks for the help,
Shahar
--
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http://forum.openscenegraph.org/viewtopic.php?p=54810#54810
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Re: [osg-users] Passing location-based data to a fragment shader
Sebastian Messerschmidt wrote: Hi Shahar Kosti: As you don't provide any exact numbers I can only guess. But usually I'd bind one or more textures per tile of paged set. Depending on your hardware bind of 8192x8192 textures is no problem. Can you be a bit more specific on how big the set is? Also for the hidden textures - I don't really get what you mean. My best guess is, that you mean not displayed. Therefore write a custom fragment shader and bind the data-textures along with you diffuse or whatever textures to the stateset of the tile. As the fragment shader is fully programmable, it is your choice what is done with the data. cheers Sebastian Hi Sebastian, Sorry for my late reply, it took me some time to get the data. One TXP I'm currently looking at, represents a 3000 km² area with texture resolution of 5m/pixel. Some areas have better resolution, up to 10 cm/pixel. The additional metadata has similar resolution. So obviously wouldn't fit on a single texture. Regarding your suggestions, could you elaborate on the bind one or more textures per tile of paged set approach? My current approach (which doesn't work), is to intercept paged nodes using a custom ReadFileCallback, which runs a NodeVisitor. The visitor finds all Geode objects and then the underlying geometries. I can bind a new texture to these geometries, but I'm not sure how to set the values correctly. Each texel in the new texture, should be set based on the world location of the corresponding texel in the current geometry texture. I'm not sure how to do that using the geometry vertex and texture coordinate indices. I hope this is clear enough. Thanks for the help, Shahar -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=54810#54810 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Passing location-based data to a fragment shader
Hi Shahar Kosti: Hi Sebastian, Thanks for your response. What if the data does not fit in a single 2D texture? in the worst case scenario, the terrain format would be TXP (i.e. paged) and the additional data resolution would be close to the textures resolution. Is there any way to have a set of hidden textures, and access them in the fragment shader? As you don't provide any exact numbers I can only guess. But usually I'd bind one or more textures per tile of paged set. Depending on your hardware bind of 8192x8192 textures is no problem. Can you be a bit more specific on how big the set is? Also for the hidden textures - I don't really get what you mean. My best guess is, that you mean not displayed. Therefore write a custom fragment shader and bind the data-textures along with you diffuse or whatever textures to the stateset of the tile. As the fragment shader is fully programmable, it is your choice what is done with the data. cheers Sebastian Shahar Sebastian Messerschmidt wrote: Hi Shahar, If the data is 2D and simply projected to x,y you could use a 2D texture and sample it per fragment based on generated texture coordinates -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=54683#54683 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
[osg-users] Passing location-based data to a fragment shader
Hi all, I'm trying to combine two data sources in a shader: * Terrain model - a large object in OSG or TXP formats. * Metadata grid - a data structure that provides additional information for 2D coordinates in the terrain (at a certain resolution). I'd like to use some of the additional metadata values, in a fragment shader that runs on the terrain object. In other words, modify each pixel based on an additional value from the metadata grid. I tried to pass the values as vertex attributes: compute the world location of each vertex, and set the vertex attribute from the metadata grid. That didn't work very well, as the additional data resolution is very high, almost the same as the terrain textures, and the vertices are too far apart from each other. How would you recommend to pass the required data from the application to the shader? Thanks, Shahar -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=54673#54673 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Passing location-based data to a fragment shader
Hi Shahar, If the data is 2D and simply projected to x,y you could use a 2D texture and sample it per fragment based on generated texture coordinates Hi all, I'm trying to combine two data sources in a shader: * Terrain model - a large object in OSG or TXP formats. * Metadata grid - a data structure that provides additional information for 2D coordinates in the terrain (at a certain resolution). I'd like to use some of the additional metadata values, in a fragment shader that runs on the terrain object. In other words, modify each pixel based on an additional value from the metadata grid. I tried to pass the values as vertex attributes: compute the world location of each vertex, and set the vertex attribute from the metadata grid. That didn't work very well, as the additional data resolution is very high, almost the same as the terrain textures, and the vertices are too far apart from each other. How would you recommend to pass the required data from the application to the shader? Thanks, Shahar -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=54673#54673 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Passing location-based data to a fragment shader
Hi Sebastian, Thanks for your response. What if the data does not fit in a single 2D texture? in the worst case scenario, the terrain format would be TXP (i.e. paged) and the additional data resolution would be close to the textures resolution. Is there any way to have a set of hidden textures, and access them in the fragment shader? Shahar Sebastian Messerschmidt wrote: Hi Shahar, If the data is 2D and simply projected to x,y you could use a 2D texture and sample it per fragment based on generated texture coordinates -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=54683#54683 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
