Hi Chris,
It's not possible to determine what error you have made from the snippets
included. The snippet of code you did include didn't show how or whether
you added the osg::Program to the StateSet, or whether you attached a
vertex shader.
I would recommend starting from one of the examples like osgshaders and the
shaders in the OpenSceneGraph-Data/shaders set.
Robert.
On 26 January 2015 at 14:51, Chris Hidden <ch...@erghis.com> wrote:
> Hey Robert, thanks for answer, hope you had a great weekend!
>
> I've been trying to read up on vertex shaders and fragment shaders and
> maybe I am not quite understanding.
>
> Im trying to attach a very basic fragment shader, but I can't seem to get
> it to work and I am not sure why.
>
> I keep getting the error "Duplicate function definitions for "main";
> prototype: "main()" found.
>
> I've looked at 2 or 3 of the examples and it seems perfectly fine to
> attach two shader files, one .vert and one .frag to a single program.
>
> Specifically the program in osghardwareanimation example. I only added
> these lines of code to the existing example to get the duplicate main error:
>
>
> Code:
>
> osg::ref_ptr<osg::Shader> fragshader;
> osg::ref_ptr<osg::Image> image =
> osgDB::readImageFile("Images/PNG/Erghis_Hands_Texture.png");
> osg::ref_ptr<osg::Texture2D> texture = new osg::Texture2D();
> texture->setImage(image);
>
> osg::ref_ptr<osg::StateSet> ss = new osg::StateSet;
> ss->setTextureAttributeAndModes(0, texture,
> osg::StateAttribute::ON);
>
> osg::ref_ptr<osg::Uniform> unifo = new
> osg::Uniform("Hand_Texture", texture.get());
> fragshader = osg::Shader::readShaderFile(osg::Shader::FRAGMENT,
> "C:/OpenSceneGraph/files/shaders/rain.frag");
>
> if (!fragshader.valid())
> osg::notify(osg::WARN) << "RigTransformHardware can't load
> FragmentShader" << std::endl;
> program->addShader(fragshader.get());
>
> ss->addUniform(unifo);
>
>
>
>
> I added this block right before the state change applications at the end
> of the init() function. I must be missing something stupid because I've
> googled the error and looked at the other examples and no one seems to be
> having this problem. What am I doing wrong?
>
> This happens with any .frag shader I load. Not just the one I wrote which
> for the sake of showing you is simply:
>
> uniform sampler2D myTexture;
>
> void main(void)
> {
> vec4 color = texture2D(myTexture, gl_TexCoord[0].st);
> gl_FragColor = color;
> }
>
> ------------------
> Read this topic online here:
> http://forum.openscenegraph.org/viewtopic.php?p=62482#62482
>
>
>
>
>
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>
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