glm::vec3 cubePositions[] = {
    glm::vec3( 0.0f,  0.0f,  0.0f),
    glm::vec3( 2.0f,  5.0f, -15.0f),
    glm::vec3(-1.5f, -2.2f, -2.5f),
    glm::vec3(-3.8f, -2.0f, -12.3f),
    glm::vec3( 2.4f, -0.4f, -3.5f),
    glm::vec3(-1.7f,  3.0f, -7.5f),
    glm::vec3( 1.3f, -2.0f, -2.5f),
    glm::vec3( 1.5f,  2.0f, -2.5f),
    glm::vec3( 1.5f,  0.2f, -1.5f),
    glm::vec3(-1.3f,  1.0f, -1.5f)
};