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Help => General => Topic started by: noodlesgc on June 27, 2009, 03:33:59 am

Title: [SOLVED] Clicking On Items
Post by: noodlesgc on June 27, 2009, 03:33:59 am

I am trying to create a window that is full of Sprites.
The user will have to click on the sprites. As far as I can tell, the only possible way to do this is check for a Event.MouseButtonPressed, and then loop through the objects, and determine if the click was on top of the object.

Is there a better way to do this? Ideally there would be a way to create a function for each sprite e.g. OnMouseButtonPressed for each Sprite.

Thanks for any input.


(also first post!  :D )

Title: [SOLVED] Clicking On Items
Post by: e_barroga on June 27, 2009, 05:20:40 pm

It works the same either way.... if you give the object a "Collision Method" the container will still need to iterate through the list of entities.

Title: [SOLVED] Clicking On Items
Post by: heishe on June 27, 2009, 06:08:23 pm

if you build a gui around it, it will be nothing more than cycling through every sprite, only that it looks more pretty. so no, there's no other way.

Title: [SOLVED] Clicking On Items
Post by: noodlesgc on June 27, 2009, 06:16:30 pm

Thanks for the replies. I guess I'll just continue the way that I'm doing it now.

Title: [SOLVED] Clicking On Items
Post by: Nexus on June 28, 2009, 01:00:25 am

Quote from: "heishe"

so no, there's no other way.

Yes, there is.

@ noodlesgc:
Instead of iterating the full container, which requires linear complexity, you could store the sprites inside an associative container like std::set. Sorting criterion might be the position (for example first x, then y coordinate). Like this, you only have O(log(n)) to determine the right sprite. If the sprites are even aligned in a rectangular wire, you can calculate the corresponding sprite subscript by its position in O(1).

Title: [SOLVED] Clicking On Items
Post by: noodlesgc on June 28, 2009, 06:10:26 pm

Quote from: "Nexus"

Quote from: "heishe"

so no, there's no other way.

Yes, there is.

@ noodlesgc:
Instead of iterating the full container, which requires linear complexity, you could store the sprites inside an associative container like std::set. Sorting criterion might be the position (for example first x, then y coordinate). Like this, you only have O(log(n)) to determine the right sprite. If the sprites are even aligned in a rectangular wire, you can calculate the corresponding sprite subscript by its position in O(1).

That's a good idea, I never would have thought of that.
Thanks