standalone/001_triangle_glut_gles3.cpp

Shows the basic usage of OGLplus with GLUT and GLES3.Copyright 2008-2014 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 <GLES3/gl3.h>

#include <oglplus/all.hpp>

#define GL_GLEXT_LEGACY 1
#include <GL/glut.h>

class Example
{
private:
    oglplus::Context gl;

    oglplus::VertexShader vs;

    oglplus::FragmentShader fs;

    oglplus::Program prog;

    oglplus::VertexArray triangle;

    oglplus::Buffer verts;
public:
    Example(void)
    {
        using namespace oglplus;

        // Set the vertex shader source
        vs.Source(
            "#ifdef GL_ES\n"
            "#version 300 es\n"
            "#else\n"
            "#version 330\n"
            "#endif\n"
            "in vec3 Position;"
            "void main(void)"
            "{"
            "   gl_Position = vec4(Position, 1.0);"
            "}"
        );
        // compile it
        vs.Compile();

        // set the fragment shader source
        fs.Source(
            "#ifdef GL_ES\n"
            "#version 300 es\n"
            "#else\n"
            "#version 330\n"
            "#endif\n"
            "out vec4 fragColor;"
            "void main(void)"
            "{"
            "   fragColor = vec4(0.0, 1.0, 0.0, 1.0);"
            "}"
        );
        // compile it
        fs.Compile();

        // release the shader compiler
        Shader::ReleaseCompiler();

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

        // bind the VAO for the triangle
        triangle.Bind();

        GLfloat triangle_verts[9] = {
            -1.0f,-1.0f, 0.0f,
             1.0f,-1.0f, 0.0f,
            -1.0f, 1.0f, 0.0f
        };
        // bind the VBO for the triangle vertices
        verts.Bind(Buffer::Target::Array);
        // upload the data
        Buffer::Data(
            Buffer::Target::Array,
            9,
            triangle_verts
        );
        // setup the vertex attribs array for the vertices
        VertexArrayAttrib vert_attr(prog, "Position");
        vert_attr.Setup<GLfloat>(3);
        vert_attr.Enable();

        gl.ClearColor(0.2f, 0.2f, 0.2f, 0.0f);
        gl.ClearDepth(1.0f);
    }

    void Display(void)
    {
        using namespace oglplus;

        gl.Clear().ColorBuffer().DepthBuffer();

        gl.DrawArrays(PrimitiveType::Triangles, 0, 3);
    }
};

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+GLES3");

    try
    {
        SingleExample example;
        glutDisplayFunc(&SingleExample::Display);
        glutMainLoop();
        return 0;
    }
    catch(oglplus::Error& err)
    {
        std::cerr
            << "Error (in "
            << err.GLFunc()
            << "'): "
            << err.what()
            << " ["
            << err.SourceFile()
            << ":"
            << err.SourceLine()
            << "] "
            << std::endl;
    }
    return 1;
}