Need explaination for 2D game development


I try to develop a 2D game using urho and I have some questions.

I saw there is a class LogicComponent to develop a custom component. But this class uses physic event. So, I want to develop the same class but using the 2D physic events.

These are my questions :

  • What is the difference between E_UPDATE and E_SCENEUPDATE events ?

I don’t understand what is the PIXEL_SIZE constant and why is it useful.


Sorry for my bad English.


(in international spirit, no apologies for English Second Language are necessary… especially if it’s perfect :wink: )

Here are specific pages on physics and events: … ysics.html … ho2_d.html
Those, and the 2D samples, are probably better than my explanations.

E_UPDATE is an application-wide update event.
E_SCENEUPDATE is specific to Scene and scene nodes, and is not sent if scene updates are disabled.
LogicComponent is just a convenience subclass of Component (it makes the samples simpler); you can just create your own Component.

PIXEL_SIZE - I have not used this in Urho, so am not sure. Typically, it’s a device/density-independent pixel abstraction, allowing applications to work in pixels while the graphics converts to device/real pixels.

EDIT: Explained here Simple 2D game tutorial for beginners


Thank you for your answer.

Firstly, I think I’m going to do like you and I won’t use PIXEL_SIZE.

I think I will use E_UPDATE like describe in the documentation and if later I see I need the E_SCENEUPDATE I will use it.