standalone/002_dsa_buffer.cpp

Shows usage of the direct state access buffer wrapperCopyright 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 "glut_glew_example.hpp"

#include <oglplus/all.hpp>
#include <oglplus/ext/EXT_direct_state_access/buffer.hpp>

#include <vector>

class DSABufferExample
 : public oglplus::StandaloneExample
{
private:
    oglplus::Context gl;

    oglplus::Program prog;

    static oglplus::Program make_prog(void)
    {
        using namespace oglplus;

        Program prog;

        Shader vs(ShaderType::Vertex);
        vs.Source(" \
            #version 330\n \
            in vec4 Position; \
            in vec2 Coord; \
            out vec2 vertCoord; \
            void main(void) \
            { \
                gl_Position = Position; \
                vertCoord = Coord; \
            } \
        ").Compile();

        Shader fs(ShaderType::Fragment);
        fs.Source(" \
            #version 330\n \
            in vec2 vertCoord; \
            out vec3 fragColor; \
            void main(void) \
            { \
                vec2 z = vec2(0.0, 0.0); \
                vec2 c = vertCoord; \
                int i = 0, max = 128; \
                while((i != max) && (distance(z, c) < 2.0)) \
                { \
                    vec2 zn = vec2( \
                        z.x * z.x - z.y * z.y + c.x, \
                        2.0 * z.x * z.y + c.y \
                    ); \
                    z = zn; \
                    ++i; \
                } \
                float a = pow(float(max-i) / float(max), 16.0); \
                fragColor = vec3(a, a, a); \
            } \
        ").Compile();

        prog.AttachShader(vs).AttachShader(fs).Link().Use();

        return prog;
    }

    oglplus::VertexArray quad;

    oglplus::DSABufferEXT positions, coords;

public:
    DSABufferExample(int /*argc*/, const char** /*argv*/)
     : gl()
     , prog(make_prog())
    {
        using namespace oglplus;

        quad.Bind();

        GLfloat rectangle_verts[8] = {
            -1.0f, -1.0f,
            -1.0f,  1.0f,
             1.0f, -1.0f,
             1.0f,  1.0f
        };
        positions.target = Buffer::Target::Array;
        positions.Data(rectangle_verts);
        positions.Bind();
        (prog|"Position").Setup<Vec2f>().Enable();

        GLfloat rectangle_coords[8] = {
            -1.4f,  0.0f,
            -1.4f,  1.0f,
             0.0f,  0.0f,
             0.0f,  1.0f
        };
        coords.target = Buffer::Target::Array;
        coords.Data(rectangle_coords);
        coords.Bind();
        (prog|"Coord").Setup<Vec2f>().Enable();

        coords.Unbind();

        gl.Disable(Capability::DepthTest);
    }

    void Render(void)
    {
        using namespace oglplus;

        gl.DrawArrays(PrimitiveType::TriangleStrip, 0, 4);
    }

    void Reshape(void)
    {
        using namespace oglplus;

        gl.Viewport(Width(), Height());
    }
};

int main(int argc, char* argv[])
{
    return oglplus::GlutGlewMain<DSABufferExample>(
        "Example of EXT_direct_state_access buffer usage",
        argc, argv
    );
}