Your application has not to vary. Therefor we have the delta value in
process and _physicsprocess . You can multiply delta with certain
actions to make your application "frame rate" independent.
In this case I need the app to run at maximum fps so that the drawing stroke is smooth:
1 - save the most points in an array, these would be the position of the mouse, while applying a linear interpolation between each point.
2- while drawing, call the _draw function to see the trace in real time.
Therefore, it is convenient that the fps are not limited to 60. The number of points saved per unit of time depends on the final fps.
I am also aware that godot is more suitable for games and not for pixel drawing applications. But to clarify a little how godot is related to the graphics card. And now it is clearer, thanks for your response.