Method initializeGL

compute/example/nbody.cpp:123–166

}

void NBodyWidget::initializeGL()
{
    // create context, command queue and program
    m_context = compute::opengl_create_shared_context();
    m_queue = compute::command_queue(m_context, m_context.get_device());
    m_program = compute::program::create_with_source(source, m_context);
    m_program.build();

    // prepare random particle positions that will be transferred to the vbo
    float4_* temp = new float4_[m_particles];
    boost::random::uniform_real_distribution<float> dist(-0.5f, 0.5f);
    boost::random::mt19937_64 gen;
    for(size_t i = 0; i < m_particles; i++) {
        temp[i][0] = dist(gen);
        temp[i][1] = dist(gen);
        temp[i][2] = dist(gen);
        temp[i][3] = 1.0f;
    }

    // create an OpenGL vbo
    GLuint vbo = 0;
    glGenBuffers(1, &vbo);
    glBindBuffer(GL_ARRAY_BUFFER, vbo);
    glBufferData(GL_ARRAY_BUFFER, m_particles*sizeof(float4_), temp, GL_DYNAMIC_DRAW);

    // create a OpenCL buffer from the vbo
    m_position = compute::opengl_buffer(m_context, vbo);
    delete[] temp;

    // create buffer for velocities
    m_velocity = new compute::vector<float4_>(m_particles, m_context);
    compute::fill(m_velocity->begin(), m_velocity->end(), float4_(0.0f, 0.0f, 0.0f, 0.0f), m_queue);

    // create compute kernels
    m_velocity_kernel = m_program.create_kernel("updateVelocity");
    m_velocity_kernel.set_arg(0, m_position);
    m_velocity_kernel.set_arg(1, m_velocity->get_buffer());
    m_velocity_kernel.set_arg(2, m_dt);
    m_velocity_kernel.set_arg(3, m_particles);
    m_position_kernel = m_program.create_kernel("updatePosition");
    m_position_kernel.set_arg(0, m_position);
    m_position_kernel.set_arg(1, m_velocity->get_buffer());
    m_position_kernel.set_arg(2, m_dt);
}
void NBodyWidget::resizeGL(int width, int height)
{
    // update viewport