Pass through example of OpenSceneGraph vertex + shader shaders with OpenGL 4.00

osg-shader-pass.cpp

#include <Windows.h> // comment if not Windows

#include <osg/Camera>
#include <osg/Drawable>
#include <osg/Geode>
#include <osg/Geometry>
#include <osg/Group>
#include <osg/Node>
#include <osg/NodeVisitor>
#include <osg/Object>
#include <osg/PrimitiveSet>
#include <osg/Program>
#include <osg/Shader>
#include <osg/StateSet>
#include <osg/Transform>
#include <osg/Uniform>
#include <osgViewer/Viewer>

#define GLSL400(src) "#version 400\n" #src

const char* vertSource = GLSL400 (
    uniform mat4 ModelViewProjectionMatrix;
    layout(location = 0) in vec4 Vertex;
void main(void)
{
    gl_Position = ModelViewProjectionMatrix * Vertex;
}
);

const char* fragSource = GLSL400(
void main(void)
{
    gl_FragColor = vec4(0,1,0,1);
}
);

struct ModelViewProjectionMatrixCallback: public osg::Uniform::Callback {
	ModelViewProjectionMatrixCallback(osg::Camera* camera) :
			_camera(camera) {
	}

	virtual void operator()(osg::Uniform* uniform, osg::NodeVisitor* nv) {
		osg::Matrixd viewMatrix = _camera->getViewMatrix();
		osg::Matrixd modelMatrix = osg::computeLocalToWorld(nv->getNodePath());
		osg::Matrixd modelViewProjectionMatrix = modelMatrix * viewMatrix * _camera->getProjectionMatrix();
		uniform->set(modelViewProjectionMatrix);
	}

	osg::Camera* _camera;
};

int main(int, char**)
{
    ::SetProcessDPIAware(); // comment if not windows

    osgViewer::Viewer viewer;
    osg::Camera* camera = viewer.getCamera();

    osg::ref_ptr<osg::Group> root = new osg::Group();

    osg::Vec3Array* vertices = new osg::Vec3Array;
    osg::Vec4Array* colors = new osg::Vec4Array;

    vertices->setName("Vertex");
    vertices->push_back(osg::Vec3f(0,0,0));
    vertices->push_back(osg::Vec3f(1,0,0));
    vertices->push_back(osg::Vec3f(1,0,1));
    vertices->push_back(osg::Vec3f(0,0,1));

    colors->setName("Color");
    colors->push_back(osg::Vec4f(1,0,0,1));
    colors->push_back(osg::Vec4f(0,1,0,1));
    colors->push_back(osg::Vec4f(1,0,1,1));
    colors->push_back(osg::Vec4f(0,0,1,1));

    // create geometry
    osg::ref_ptr<osg::Geometry> geom = new osg::Geometry;
    geom->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::QUADS,0,vertices->size()));
    geom->setUseDisplayList(false);

    // defaults
    geom->setVertexArray(vertices);
    geom->setColorArray(colors, osg::Array::BIND_PER_VERTEX);

    // set attributes
    geom->setVertexAttribArray(0, vertices, osg::Array::BIND_PER_VERTEX);

    // create shader
    osg::ref_ptr<osg::Program> program = new osg::Program;
    program->setName("shader");
    program->addShader(new osg::Shader(osg::Shader::VERTEX, vertSource));
    program->addShader(new osg::Shader(osg::Shader::FRAGMENT, fragSource));

    osg::ref_ptr<osg::Geode> geode = new osg::Geode;
    geode->addDrawable(geom.get());

	  osg::StateSet* state = geode->getOrCreateStateSet();
    state->setAttributeAndModes(program.get(), osg::StateAttribute::ON);

    // add uniforms
    osg::Uniform* modelViewProjectionMatrix = new osg::Uniform(osg::Uniform::FLOAT_MAT4, "ModelViewProjectionMatrix");
    modelViewProjectionMatrix->setUpdateCallback(new ModelViewProjectionMatrixCallback(camera));
    state->addUniform(modelViewProjectionMatrix);

    // turn lights off
    state->setMode(GL_LIGHTING, osg::StateAttribute::OFF);
    state->setMode(GL_BLEND, osg::StateAttribute::ON);

    // scene state run
    root->addChild(geode.get());
    viewer.setSceneData(root.get());
    viewer.setUpViewOnSingleScreen(0); 
    return viewer.run();
}