Re: [osg-users] shadows and custom shaders
Hi guys, So I have been reworking to support the shadows. Does the tex gen coords get stored in the texture matrix? Am I wrong to assume I can still use the fixed-function tex gen coords with a shader? Werner, I noticed you said you replaced the OSG shader with your own. Do you happen to know what happens when you stop using an uber-shader to render everything in your scene. My scene has many shaders in the graph. To me it seems like some data might be getting overridden down the traversal of the scene. Thanks. -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=32056#32056 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] shadows and custom shaders
Hi Michael, So I have been reworking to support the shadows. Does the tex gen coords get stored in the texture matrix? Am I wrong to assume I can still use the fixed-function tex gen coords with a shader? Texture coordinate generation is done by the Vertex stage, so as soon as you start using a vertex shader you need to do tex coord generation for your shadow texture unit too. Check the vertex shaders in src/osgShadow/StandardShadowMap.cpp for guidance. I noticed you said you replaced the OSG shader with your own. Do you happen to know what happens when you stop using an uber-shader to render everything in your scene. My scene has many shaders in the graph. To me it seems like some data might be getting overridden down the traversal of the scene. If you use different shaders on different nodes, you need to do shadow texgen computation (vertex shader) and shadow application (fragment shader) in all of them. You can easily factor out those functions into small shader files that you will include everywhere you use your own shaders. That's what the shaders in StandardShadowMap.cpp do - the main shader declares a DynamicShadow() function and calls it, and the shadow shader defines that function. You can do the same, just write your own main shader, declaring the DynamicShadow() function and calling it, and include the same shadow shader (with the code of DynamicShadow()) in all of them. Hope this helps, J-S -- __ Jean-Sebastien Guayjean-sebastien.g...@cm-labs.com http://www.cm-labs.com/ http://whitestar02.webhop.org/ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] shadows and custom shaders
Thanks J-S. Yea I finally got it working. I did it by taking over the cull step of the shadow maps and getting rid of the fixed function tex gen and then pushing the matrices for the shadow projection into my vertex shaders and doing the math there. Thanks for your help. -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=32058#32058 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] shadows and custom shaders
Hi Michael,
Thanks J-S. Yea I finally got it working. I did it by taking over the cull step
of the shadow maps and getting rid of the fixed function tex gen and then
pushing the matrices for the shadow projection into my vertex shaders and doing
the math there.
I think you may have overcomplicated things for yourself a bit... You
dind't have to remove any fixed function state at all, since when you
use shaders it's implicitly replaced by your shader. Also, in the shader
you have everything you need to be able to calculate the texgen already
(care of the TexGen and some other calculations). This is all spelled
out in the shaders at the top of src/osgShadow/StandardShadowMap.cpp, as
I mentioned before.
You have a function called DynamicShadow:
void DynamicShadow( in vec4 ecPosition )
{
// generate coords for shadow mapping
gl_TexCoord[1].s = dot( ecPosition, gl_EyePlaneS[1] );
gl_TexCoord[1].t = dot( ecPosition, gl_EyePlaneT[1] );
gl_TexCoord[1].p = dot( ecPosition, gl_EyePlaneR[1] );
gl_TexCoord[1].q = dot( ecPosition, gl_EyePlaneQ[1] );
}
(the gl_EyePlane* are set up by the TexGen) and you call it like this:
vec4 ecPos = gl_ModelViewMatrix * gl_Vertex;
DynamicShadow( ecPos );
And as I said, you can put the first part in a file that you will add to
every osg::Program you have, in addition to your own shader that will
have the second set of lines in it. Same for the fragment shader,, where
you would do the shadowmap lookup using the texcoords that were
calculated above in the vertex shader. That way you're not duplicating
much code, you're reusing the same file in many places. And you're
working within the system instead of replacing big parts of it, which I
find preferable since it's less prone to break later on if OSG changes.
Anyways, good to know you have something that works, but I just wanted
to point out that there may be a better way.
J-S
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__
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http://whitestar02.webhop.org/
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[osg-users] shadows and custom shaders
Hi, So I have been experimenting with shadows in OSG using the ShadowMap shadow technique. With the default OSG implementation and every custom shader in my scene graph disabled the shadows work correctly. Once I turn my shaders on they stop working. This is understandable as he OSG shadow shader will be overridden. I then reimplemented the shadow projection code in my pixel shaders, but then still no shadows. I am not too familiar with the OpenGL fixed-function shadow pipeline. If you do not provide a vertex shader does OpenGL generate the proper texture coordinates by default. I saw that OSG was creating a TexGen attribute and applying that after shadow map creation. If I am implementing custom vertex shaders should I be overriding the ShadowMap and not allowing that TexGen to be created and then generate the proper texture coordinates in my vertex shader? At this point I think all that is missing is the proper texture coordinates for shadows to be working for me. Any help woul d be appreciated. Thanks in advance! Cheers, Michael -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=31896#31896 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] shadows and custom shaders
Hello Michael, If I am implementing custom vertex shaders should I be overriding the ShadowMap and not allowing that TexGen to be created and then generate the proper texture coordinates in my vertex shader? At this point I think all that is missing is the proper texture coordinates for shadows to be working for me. Your intuition is correct, but you just need to calculate the shadow texture coordinates for the shadow texture unit. No need to disable the osg::TexGen because since it's fixed-function state, it will just be ignored when using a vertex shader. As has been said before, once you start using shaders for a given stage you need to do everything the fixed pipeline would have done for you in your shader for that stage yourself (at least, what you need). That includes fog, texgen, etc. J-S -- __ Jean-Sebastien Guayjean-sebastien.g...@cm-labs.com http://www.cm-labs.com/ http://whitestar02.webhop.org/ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] shadows and custom shaders
Hi J-S, Thanks for the swift reply, good to know I was on the correct path. -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=31904#31904 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] shadows and custom shaders
Hi Michael,
You are right. There can only be one shader program loaded which has to do all
the work.
If you overload the default shader from osgShadow, it has to do that work
together with your new stuff.
In my case I just created my own class Cl_SoftShadowMap, derived from
osgSoftShadowmap. I reimplemented two methods:
// If our shader needs additional uniforms, they may be set here
void Cl_SoftShadowMap::createUniforms() {
_uniformList.clear();
SoftShadowMap::createUniforms();
// This Variable will be set by any node using textures
_uniformList.push_back(new osg::Uniform(USE_TEXTURE_UNIFORM, false));
// Shadow creation can be switched on an off (we still need our shaders)
useShadowUniform = new osg::Uniform(USE_SHADOW_MAP_UNIFORM, useShadow);
_uniformList.push_back(useShadowUniform.get());
// Toggle between soft and hard shadows
useSoftShadowUniform = new osg::Uniform(USE_SOFT_SHADOW_UNIFORM,
useSoftShadow);
_uniformList.push_back(useSoftShadowUniform.get());
// Uniforms used for bump mapping
_uniformList.push_back(new osg::Uniform(USE_BUMP_MAP_UNIFORM, false));
_uniformList.push_back(new osg::Uniform(bumpMap, BUMP_TEXTURE_UNIT));
}
// We create our own shaders
void Cl_SoftShadowMap::createShaders(bool _enableShadow,
bool _enableBumpMapping,
bool _enableDisplacementMapping) {
if( _shaderList.empty() ) {
osg::ref_ptrosg::Shader vertexShader;
vertexShader = Cl_ShaderGen::getShader(osg::Shader::VERTEX,
_enableShadow,
_enableBumpMapping,
_enableDisplacementMapping);
_shaderList.push_back(vertexShader);
osg::ref_ptrosg::Shader fragmentShader;
fragmentShader = Cl_ShaderGen::getShader(osg::Shader::FRAGMENT,
_enableShadow,
_enableBumpMapping,
_enableDisplacementMapping);
_shaderList.push_back(fragmentShader);
}
}
By this way your own shaders get loaded an you can create any uniform youneed.
You can use it by calling shadowScene-setShadowTechnique(...);
I hope this helps.
- Werner -
On Tuesday 21 September 2010 15:25:23 Michael Irby II wrote:
Hi,
So I have been experimenting with shadows in OSG using the ShadowMap shadow
technique. With the default OSG implementation and every custom shader in
my scene graph disabled the shadows work correctly. Once I turn my shaders
on they stop working. This is understandable as he OSG shadow shader will
be overridden. I then reimplemented the shadow projection code in my pixel
shaders, but then still no shadows. I am not too familiar with the OpenGL
fixed-function shadow pipeline. If you do not provide a vertex shader does
OpenGL generate the proper texture coordinates by default. I saw that OSG
was creating a TexGen attribute and applying that after shadow map
creation. If I am implementing custom vertex shaders should I be
overriding the ShadowMap and not allowing that TexGen to be created and
then generate the proper texture coordinates in my vertex shader? At this
point I think all that is missing is the proper texture coordinates for
shadows to be working for me. Any help woul d be appreciated. Thanks in
advance!
Cheers,
Michael
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