void CGLMap::paintGL()
{
glClear(GL_COLOR_BUFFER_BIT);
GLuint VBO;
GLuint arr[4];
arr[0] = -0.5f;
arr[1] = -0.5f;
arr[2] = 0.5f;
arr[3] = 0.5f;
glGenBuffers(1, &VBO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(arr), arr, GL_STATIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, 0);
glColor4f(255.0, 0.0, 0.0, 1.0);
glDrawArrays(GL_LINES, 0, sizeof(arr));
}