C++ / D2D1 / Child class: Exception thrown: read access violation. this was nullptr.

Question

Hello, I'm trying to create a child class for my main Direct2D class to put all the generic shapes drawing functions in there to keep the main class clean

//parent class definition

class CD2DCore {
protected:
    //COM objects - always release
    ID2D1Factory* gFactory;         //generates D2D resources
    ID2D1HwndRenderTarget* gRT;     //target to draw graphics at
    ID2D1SolidColorBrush* gBrush;   //main brush
public:
    CD2DCore();
    ~CD2DCore();

//......
//rest of CD2DCore code

//child class definition

class CD2DBasic : public CD2DCore {
public:

    //basic shapes framework
    void DrawLine(float x1, float y1, float x2, float y2, float r, float g, float b, float a = 1.0f, float strokeW = 1.0f);

//......
//rest of CD2DBasic code

Then I create entities for both classes like so
CD2DCore* D2DCore; //class for core Direct2D methods
CD2DBasic* D2DBasic; //class for drawing basic Direct2D shapes

But when I'm trying to draw, say, a line through D2DBasic->DrawLine method I get an exception
void CD2DBasic::DrawLine(float x1, float y1, float x2, float y2, float r, float g, float b, float a, float strokeW) {
gBrush->SetColor(D2D1::ColorF(r, g, b, a));
gRT->DrawLine(D2D1::Point2F(x1, y1), D2D1::Point2F(x2, y2), gBrush, strokeW);
}
at the gBrush->SetColor... line stating "read access violation. this was nullptr."

However when I put this same method in CD2DCore - it draws the line without any issues.
I guess it somehow doesn't inherit the parent's pointers to Direct2D stuff?

How do I resolve this?

Answer 1

As far as I see, Nobody calls InitD2D which should be called in CD2DCore constructor.