Reuse matrix in glm?

Question

I have a glm::mat4 field in a class of mine representing a model transformation matrix, and I would like to update the transformation every frame. However, I would like to reuse the matrix in this field every time I update the transformation, instead of setting it to a glm::mat4(), which I imagine would waste more and more memory as the matrix that was stored there is assigned over. Am I imagining this leak? Is there a way for me to "re-identity" a matrix in glm?

Answer 1

There is no leak, what you are doing every frame is similar to int i = 1 every frame;

// Im assuming somewhere in your class you have this:
class Example{
    public:
        ...
        void Update();
        void Draw();
    private:
        glm::mat4 m_Model;
};

void Example::Update()
{
    // This will rotate the model 1 degree every time update is called
    m_Model = glm::rotate(m_Model, 1.0f, glm::vec3(1, 0, 0);
}

void Example::Draw()
{
    glUniformMatrix4fv(1, GL_FALSE, GL_FALSE, glm::value_ptr(m_Model));
    // Draw model etc.. 
};

The point is that you don't have to set m_Model to glm::mat4 every frame if you're just keeping it at a static position ( it's always at x,y,z position ), that's equivalent to setting int i = 1 every single update, it's pointless as it is stored in your classes memory and retains the last value set until the class is destroyed.