standalone/002_rectangle_glut_glew.cpp

Shows the basic usage of OGLplus with GLUT and GLEW.Copyright 2008-2012 Matus Chochlik. Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

#include <cassert>
#include <iostream>

#include <GL/glew.h>
#include <GL/glut.h>

#include <oglplus/all.hpp>

class Example
{
private:
    oglplus::Context gl;

    oglplus::VertexShader vs;

    oglplus::GeometryShader gs;

    oglplus::FragmentShader fs;

    oglplus::Program prog;
public:
    Example(void)
    {
        using namespace oglplus;

        // Set the vertex shader source
        vs.Source(" \
            #version 330\n \
            void main(void) { } \
        ");
        // compile it
        vs.Compile();

        // Set the geometry shader source
        gs.Source(" \
            #version 330\n \
            layout (points) in; \
            layout (triangle_strip, max_vertices=4) out;\
            out vec3 geomColor; \
            void main(void) \
            { \
                gl_Position = vec4(-1.0,-1.0, 0.0, 1.0); \
                geomColor = vec3(0.0, 0.0, 0.0); \
                EmitVertex(); \
                gl_Position = vec4(-1.0, 1.0, 0.0, 1.0); \
                geomColor = vec3(1.0, 0.0, 0.0); \
                EmitVertex(); \
                gl_Position = vec4( 1.0,-1.0, 0.0, 1.0); \
                geomColor = vec3(0.0, 1.0, 0.0); \
                EmitVertex(); \
                gl_Position = vec4( 1.0, 1.0, 0.0, 1.0); \
                geomColor = vec3(0.0, 0.0, 1.0); \
                EmitVertex(); \
                EndPrimitive(); \
            } \
        ");
        // compile it
        gs.Compile();

        // set the fragment shader source
        fs.Source(" \
            #version 330\n \
            in vec3 geomColor; \
            out vec3 fragColor; \
            void main(void) \
            { \
                fragColor = geomColor; \
            } \
        ");
        // compile it
        fs.Compile();

        // attach the shaders to the program
        prog.AttachShader(vs);
        prog.AttachShader(gs);
        prog.AttachShader(fs);
        // link and use it
        prog.Link();
        prog.Use();
    }

    void Display(void)
    {
        using namespace oglplus;

        gl.DrawArrays(PrimitiveType::Points, 0, 1);
    }
};

class SingleExample
{
private:
    static Example*& SingleInstance(void)
    {
        static Example* test = nullptr;
        return test;
    }

    SingleExample(const SingleExample&);
public:

    SingleExample(void)
    {
        assert(!SingleInstance());
        SingleInstance() = new Example();
    }

    ~SingleExample(void)
    {
        assert(SingleInstance());
        delete SingleInstance();
        SingleInstance() = nullptr;
    }

    static void Display(void)
    {
        assert(SingleInstance());
        SingleInstance()->Display();
        glutSwapBuffers();
    }
};

int main(int argc, char* argv[])
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH);
    glutInitWindowSize(800, 600);
    glutInitWindowPosition(100,100);
    glutCreateWindow("OGLplus+GLUT+GLEW");

    if(glewInit() == GLEW_OK) try
    {
        glGetError();
        SingleExample example;
        glutDisplayFunc(&SingleExample::Display);
        glutMainLoop();
        return 0;
    }
    catch(oglplus::ProgramBuildError& pbe)
    {
        std::cerr <<
            "Error (in " << pbe.GLSymbol() << ", " <<
            pbe.ClassName() << ": '" <<
            pbe.ObjectDescription() << "'): " <<
            pbe.what() << ": " <<
            pbe.Log() <<
            std::endl;
        pbe.Cleanup();
    }
    catch(oglplus::Error& err)
    {
        std::cerr <<
            "Error (in " << err.GLSymbol() << ", " <<
            err.ClassName() << ": '" <<
            err.ObjectDescription() << "'): " <<
            err.what() <<
            " [" << err.File() << ":" << err.Line() << "] ";
        std::cerr << std::endl;
        err.Cleanup();
    }
    return 1;
}