From Paul Martz, a simple GL3 example

examples/CMakeLists.txt

@@ -154,6 +154,9 @@ IF(DYNAMIC_OPENSCENEGRAPH)
     ADD_SUBDIRECTORY(osgwidgetwindow)
     ADD_SUBDIRECTORY(osguserdata)
 
+    # GL3/GL4 example
+    ADD_SUBDIRECTORY(osgsimplegl3)
+
     IF(OSG_CPP_EXCEPTIONS_AVAILABLE)
         ADD_SUBDIRECTORY(osgunittests)
         ADD_SUBDIRECTORY(osgmemorytest)

examples/osgsimplegl3/CMakeLists.txt

@@ -0,0 +1,4 @@
+SET(TARGET_SRC osgsimplegl3.cpp )
+
+#### end var setup  ###
+SETUP_EXAMPLE(osgsimplegl3)

examples/osgsimplegl3/osgsimplegl3.cpp

@@ -0,0 +1,171 @@
+// This is public domain software and comes with
+// absolutely no warranty. Use of public domain software
+// may vary between counties, but in general you are free
+// to use and distribute this software for any purpose.
+
+
+// Example: OSG using an OpenGL 3.1 context.
+// The comment block at the end of the source describes building OSG
+// for use with OpenGL 3.x.
+
+#include <osgViewer/Viewer>
+#include <osgDB/ReadFile>
+#include <osg/GraphicsContext>
+#include <osg/Camera>
+#include <osg/Viewport>
+#include <osg/StateSet>
+#include <osg/Program>
+#include <osg/Shader>
+
+
+void configureShaders( osg::StateSet* stateSet )
+{
+    const std::string vertexSource = 
+        "#version 140 \n"
+        " \n"
+        "uniform mat4 osg_ModelViewProjectionMatrix; \n"
+        "uniform mat3 osg_NormalMatrix; \n"
+        "uniform vec3 ecLightDir; \n"
+        " \n"
+        "in vec4 osg_Vertex; \n"
+        "in vec3 osg_Normal; \n"
+        "out vec4 color; \n"
+        " \n"
+        "void main() \n"
+        "{ \n"
+        "    vec3 ecNormal = normalize( osg_NormalMatrix * osg_Normal ); \n"
+        "    float diffuse = max( dot( ecLightDir, ecNormal ), 0. ); \n"
+        "    color = vec4( vec3( diffuse ), 1. ); \n"
+        " \n"
+        "    gl_Position = osg_ModelViewProjectionMatrix * osg_Vertex; \n"
+        "} \n";
+    osg::Shader* vShader = new osg::Shader( osg::Shader::VERTEX, vertexSource );
+
+    const std::string fragmentSource = 
+        "#version 140 \n"
+        " \n"
+        "in vec4 color; \n"
+        "out vec4 fragData; \n"
+        " \n"
+        "void main() \n"
+        "{ \n"
+        "    fragData = color; \n"
+        "} \n";
+    osg::Shader* fShader = new osg::Shader( osg::Shader::FRAGMENT, fragmentSource );
+
+    osg::Program* program = new osg::Program;
+    program->addShader( vShader );
+    program->addShader( fShader );
+    stateSet->setAttribute( program );
+
+    osg::Vec3f lightDir( 0., 0.5, 1. );
+    lightDir.normalize();
+    stateSet->addUniform( new osg::Uniform( "ecLightDir", lightDir ) );
+}
+
+int main( int argc, char** argv )
+{
+    osg::ArgumentParser arguments( &argc, argv );
+
+    osg::Node* root = osgDB::readNodeFiles( arguments );
+    if( root == NULL )
+    {
+        osg::notify( osg::FATAL ) << "Unable to load model from command line." << std::endl;
+        return( 1 );
+    }
+    configureShaders( root->getOrCreateStateSet() );
+
+    const int width( 800 ), height( 450 );
+    const std::string version( "3.1" );
+    osg::ref_ptr< osg::GraphicsContext::Traits > traits = new osg::GraphicsContext::Traits();
+    traits->x = 20; traits->y = 30;
+    traits->width = width; traits->height = height;
+    traits->windowDecoration = true;
+    traits->doubleBuffer = true;
+    traits->glContextVersion = version;
+    osg::ref_ptr< osg::GraphicsContext > gc = osg::GraphicsContext::createGraphicsContext( traits.get() );
+    if( !gc.valid() )
+    {
+        osg::notify( osg::FATAL ) << "Unable to create OpenGL v" << version << " context." << std::endl;
+        return( 1 );
+    }
+
+    // Create a Camera that uses the above OpenGL context.
+    osg::Camera* cam = new osg::Camera;
+    cam->setGraphicsContext( gc.get() );
+    // Must set perspective projection for fovy and aspect.
+    cam->setProjectionMatrix( osg::Matrix::perspective( 30., (double)width/(double)height, 1., 100. ) );
+    // Unlike OpenGL, OSG viewport does *not* default to window dimensions.
+    cam->setViewport( new osg::Viewport( 0, 0, width, height ) );
+
+    osgViewer::Viewer viewer;
+    viewer.setCamera( cam );
+    viewer.setSceneData( root );
+
+    // for non GL3/GL4 and non GLES2 platforms we need enable the osg_ uniforms that the shaders will use,
+    // you don't need thse two lines on GL3/GL4 and GLES2 specific builds as these will be enable by default.
+    gc->getState()->setUseModelViewAndProjectionUniforms(true);
+    gc->getState()->setUseVertexAttributeAliasing(true);
+
+    return( viewer.run() );
+}
+
+/*
+
+Building OSG for OpenGL 3.x
+
+OSG currently support OpenGL 3.x on Windows. This comment block describes the
+necessary configuration steps.
+
+Get the draft gl3.h header file from OpenGL.org and put it in a folder called
+“GL3” somewhere on your hard drive. OSG includes this header as <GL3/gl3.h>. Get
+gl3.h from here:
+http://www.opengl.org/registry/
+
+Open the cmake-gui and load OSG's top-level CmakeLists.txt. You'll need to make
+several changes.
+
+ * Add the path to <GL3/gl3.h> to the CMake compiler flags, CMAKE_CXX_FLAGS and
+   CMAKE_CXX_FLAGS_DEBUG (for release and debug builds; others if you use other
+   build configurations). The test to add should look something like this:
+     /I “C:\GLHeader”
+   The folder GLHeader should contain a subfolder GL3, which in turn contains
+   gl3.h.
+
+ * Enable the following CMake variable:
+     OSG_GL3_AVAILABLE
+
+ * Disable the following CMake variables:
+     OSG_GL1_AVAILABLE
+     OSG_GL2_AVAILABLE
+     OSG_GLES1_AVAILABLE
+     OSG_GLES2_AVAILABLE
+     OSG_GL_DISPLAYLISTS_AVAILABLE
+     OSG_GL_FIXED_FUNCTION_AVAILABLE
+     OSG_GL_MATRICES_AVAILABLE
+     OSG_GL_VERTEX_ARRAY_FUNCS_AVAILABLE
+     OSG_GL_VERTEX_FUNCS_AVAILABLE
+
+ * Additionally, leave BUILD_OSG_EXAMPLES disabled. None of the existing
+   examples use GL3, so there's no point in building them.
+
+Create your project files in cmake-gui as usual, and build OSG as usual.
+
+If you have an external project that will depend on OSG built for OpenGL 3.x,
+you'll need to ensure your external project also uses the compiler include
+directives to find <GL3/gl3.h>.
+
+To berify your application is using a pure OpenGL 3.x context, set
+OSG_NOTIFY_LEVEL=INFO in the environment and check the console output. Context
+creation displays output such as the following:
+    GL3: Attempting to create OpenGL3 context.
+    GL3: version: 3.1
+    GL3: context flags: 0
+    GL3: profile: 0
+    GL3: context created successfully.
+
+When your app begins rendering, it displays information about the actual context
+it is using:
+    glVersion=3.1, isGlslSupported=YES, glslLanguageVersion=1.4
+
+*/