subject:"\[osg\-users\] Support for sampler arrays"

Re: [osg-users] Support for sampler arrays

2016-03-22 Thread Chris Kuliukas

Thanks Lionel & Seb, that's very helpful. When I tried setting ints to a 
Sampler2D array it said that it couldn't take ints, which is why I thought it 
wasn't supported. If I set to ints directly though it does work.


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Re: [osg-users] Support for sampler arrays

2016-03-22 Thread Sebastian Messerschmidt


Hi Chris,

Following Lionels reply I did a quick test which seems to work:

void addSamplerArray(osg::StateSet* ss)
{
osg::Uniform* uniform = new osg::Uniform(osg::Uniform::INT, "test",2);
uniform->setElement(0,0);
uniform->setElement(1,1);

osg::Texture2D* tex1 = new 
osg::Texture2D(osgDB::readImageFile("./resources/textures/tex1.png"));
osg::Texture2D* tex2 = new 
osg::Texture2D(osgDB::readImageFile("./resources/textures/tex2.png"));

ss->addUniform(uniform);
ss->setTextureAttributeAndModes(0, tex1, osg::StateAttribute::ON);
ss->setTextureAttributeAndModes(1, tex2, osg::StateAttribute::ON);
}

fragment shader:

#version 400 compatibility
uniform sampler2D test[2];
in vec2 texCoord;
void main()
{
gl_FragColor = texture2D(test[1], texCoord)*texture2D(test[0], 
texCoord);

}



Thanks, I'll have to think about whether it would be feasible for me to spend 
time in this project altering osg core..

See i do like texture arrays, they would be ideal, except that I'm dealing with 
GIS data grids, so stretching/compressing them would lose information or memory 
space. I want to be able to store several grids of various sizes at the correct 
resolution, and be able to look up data from them programmatically in the 
shaders so I can superimpose data from one layer onto another etc.
I see. But be aware that dynamic access is not allowed in every case. 
The value for the look up has some constraints:


[1] https://www.opengl.org/wiki/Data_Type_%28GLSL%29#Opaque_arrays


Cheers
Sebastian




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Re: [osg-users] Support for sampler arrays

2016-03-22 Thread Chris Kuliukas

Thanks, I'll have to think about whether it would be feasible for me to spend 
time in this project altering osg core..

See i do like texture arrays, they would be ideal, except that I'm dealing with 
GIS data grids, so stretching/compressing them would lose information or memory 
space. I want to be able to store several grids of various sizes at the correct 
resolution, and be able to look up data from them programmatically in the 
shaders so I can superimpose data from one layer onto another etc.


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Re: [osg-users] Support for sampler arrays

2016-03-22 Thread Lionel Lagarde


Hi,

The OpenGL command used to update a sampler* uniform is glUniformi[fv].
Sampler* uniforms are int uniforms.

An uniform of type 'array of INT' works (It works for me).

On 22/03/2016 10:36, Sebastian Messerschmidt wrote:

Hi Chris,

Hi,

Working on an app that is going to be doing a lot of work with large 
texture processing, and will need to squeeze as much data into 
graphics memory as possible and allow many textures to be referenced 
programmatically.


I've got texture arrays working, but can't use this for all 
requirements since all layers in a texture array have to be the same 
size.




It looks like I could use sampler arrays (e.g. sampler2D 
myTextures[20]; ), but osg::Uniform doesn't seem to support such a 
thing.
Arrays of samplers is used almost by no one any more. I usually use 
TextureArrays and simply resize the textures to a common size (usually 
the "biggest"). Texture arrays are efficient and easy to use.
I'd like to see the "array of sampler"-support in OSG anyways, since 
there might be situations where texture arrays are not efficient.
Another alternative are bindless textures, but we would need to add 
support to OSG too.

Last alternative could be a texture atlas.

Since you mentioned "texture processing", you might want to look into 
BufferTextures. They don't have any filtering (only texelfetch), but 
IIRC they support large amounts of texels.
So if you don't need HW-filtering/mipmapping you can use them as atlas 
textures.


Cheers
Sebastian



I'm also wondering if there's an easy way to easily run your own 
OpenGL commands in case something isn't supported yet and you just 
want to use GL directly instead of waiting for the OSG implementation?


Thank you!

Cheers,
Chris


http://www.hrwallingford.com/facilities/ship-simulation-centre 
(http://www.hrwallingford.com/facilities/ship-simulation-centre)


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Re: [osg-users] Support for sampler arrays

2016-03-22 Thread Sebastian Messerschmidt


Hi Chris,

Hi,

Working on an app that is going to be doing a lot of work with large texture 
processing, and will need to squeeze as much data into graphics memory as 
possible and allow many textures to be referenced programmatically.

I've got texture arrays working, but can't use this for all requirements since 
all layers in a texture array have to be the same size.




It looks like I could use sampler arrays (e.g. sampler2D myTextures[20]; ), but 
osg::Uniform doesn't seem to support such a thing.
Arrays of samplers is used almost by no one any more. I usually use 
TextureArrays and simply resize the textures to a common size (usually 
the "biggest"). Texture arrays are efficient and easy to use.
I'd like to see the "array of sampler"-support in OSG anyways, since 
there might be situations where texture arrays are not efficient.
Another alternative are bindless textures, but we would need to add 
support to OSG too.

Last alternative could be a texture atlas.

Since you mentioned "texture processing", you might want to look into 
BufferTextures. They don't have any filtering (only texelfetch), but 
IIRC they support large amounts of texels.
So if you don't need HW-filtering/mipmapping you can use them as atlas 
textures.


Cheers
Sebastian



I'm also wondering if there's an easy way to easily run your own OpenGL 
commands in case something isn't supported yet and you just want to use GL 
directly instead of waiting for the OSG implementation?

Thank you!

Cheers,
Chris


http://www.hrwallingford.com/facilities/ship-simulation-centre 
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Re: [osg-users] Support for sampler arrays

2016-03-22 Thread Robert Osfield

Hi Chris,

You can subclass from osg::StateAttribute and implement your own GL state
calls in the same way as all the core StateAttribute classes implement
their GL state calls.  The osg::Uniform is an exception though as there are
particular rules about when uniforms can be applied - you have to know that
the appropriate glProgram is applied prior to assign the uniforms to them.

osg::State manages this task, applying all osg::StateAttribute then
applying the osg::Uniform.  The add sampler arrays the natural place would
be to modify the core osg::Uniform and simply submit this for inclusion in
the core OSG.

Robert

On 22 March 2016 at 06:32, Chris Kuliukas  wrote:

> Hi,
>
> Working on an app that is going to be doing a lot of work with large
> texture processing, and will need to squeeze as much data into graphics
> memory as possible and allow many textures to be referenced
> programmatically.
>
> I've got texture arrays working, but can't use this for all requirements
> since all layers in a texture array have to be the same size.
>
> It looks like I could use sampler arrays (e.g. sampler2D myTextures[20];
> ), but osg::Uniform doesn't seem to support such a thing.
>
>
> I'm also wondering if there's an easy way to easily run your own OpenGL
> commands in case something isn't supported yet and you just want to use GL
> directly instead of waiting for the OSG implementation?
>
> Thank you!
>
> Cheers,
> Chris
>
> 
> http://www.hrwallingford.com/facilities/ship-simulation-centre (
> http://www.hrwallingford.com/facilities/ship-simulation-centre)
>
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> Read this topic online here:
> http://forum.openscenegraph.org/viewtopic.php?p=66577#66577
>
>
>
>
>
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[osg-users] Support for sampler arrays

2016-03-22 Thread Chris Kuliukas

Hi,

Working on an app that is going to be doing a lot of work with large texture 
processing, and will need to squeeze as much data into graphics memory as 
possible and allow many textures to be referenced programmatically.

I've got texture arrays working, but can't use this for all requirements since 
all layers in a texture array have to be the same size.

It looks like I could use sampler arrays (e.g. sampler2D myTextures[20]; ), but 
osg::Uniform doesn't seem to support such a thing.


I'm also wondering if there's an easy way to easily run your own OpenGL 
commands in case something isn't supported yet and you just want to use GL 
directly instead of waiting for the OSG implementation?

Thank you!

Cheers,
Chris


http://www.hrwallingford.com/facilities/ship-simulation-centre 
(http://www.hrwallingford.com/facilities/ship-simulation-centre)

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Re: [osg-users] Support for sampler arrays

Re: [osg-users] Support for sampler arrays

Re: [osg-users] Support for sampler arrays

Re: [osg-users] Support for sampler arrays

Re: [osg-users] Support for sampler arrays

Re: [osg-users] Support for sampler arrays

[osg-users] Support for sampler arrays

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