Drawing objects of a class

Monkey Forums/Monkey Programming/Drawing objects of a class

Afrobear

(Posted 2015) [#1]

Hey people! I was wondering how you guys make it so you call a single function and all objects of a same class are drawn (I mean, they will execute a method). I was thinking of saving them to an array and draw them all using a for-statement but maybe is there an easier way to do it?

Thanks in advance! :)

ImmutableOctet(SKNG)

(Posted 2015) [#2]

I have an entire class hierarchy for my personal engine(s). Ignoring the specifics of the hierarchy, I basically deal with 'WorldObjects' ('Entity' / 'Actor' functionality is built on top of this). Each 'WorldObject' has fields for their position, rotation, and scale (As well as some other fields, such as object-flags). All of my functionality for objects in the actual "world" is based on this model. From there, 'WorldObject' inherits other classes and models, but you get the basic idea. I use a "culling" routine that's tied to part of my collision-code, so I basically check if something is in the camera's view. From there, I add the objects to a stack per-camera, and I sort them based on some very basic draw-ordering techniques. I also have a "layer" system tied to that. Nothing ground breaking, but it's a lot faster than drawing everything. Sure, Monkey's scissor functionality is great, but my own systems reduce unneeded overhead further. Collision detection is done through using object-defined modes, which are backed by a managing class. Object relations and collision are handled using relatively simple quad-tree setups. I should probably do some more benchmarks on this at some point. It may just be faster to overhaul this.

That's how I handle my render step. It's basically just a matter of making a stack for each "camera", and sorting these stacks as I see fit. That being said, you personally may want to look into less memory intensive setups; for example, you could just sort the stack (Or similar collection) you use for your objects already.

Gerry Quinn

(Posted 2015) [#3]

I usually have something like:


Class GameWindow

	Field bullets:List< Bullet >


	Method Draw:Void()
		DrawBullets()
		'DrawPlayer()
		'DrawWhatever()
	End
	
	
	Method DrawBullets:Void()
		For Local b:Bullet = Eachin bullets
			b.Draw()
		End
	End

End

Basically the game window knows what categories of stuff are on it, and draws them. Unless your game is very complex, you don;t really need to automate drawing so much as keep it tidy.

I tend to have the window do the drawing as a rule (simple sprite-based games) hence the separate functions for different types.

A more sophisticated system would be to have every drawable object inherit from a base class or implement an interface, and add itself to a single list of drawables when created. Then you could just call Draw() for each item in the list.

Afrobear

(Posted 2015) [#4]

Hey guys thanks for the response. I must confess I'm a newbie yet so I don't know how lots of stuff work in Monkey. This is what I made:

Class Space Extends App
     
     Field Player:Ship[4]
     
     Field Playas:List< Ship >

     Method OnCreate()

          Seed=Millisecs
          
          Player[0]=New Ship(Rnd(8,632),Rnd(8,472),True)
          Player[1]=New Ship(Rnd(8,632),Rnd(8,472),False)
          Player[2]=New Ship(Rnd(8,632),Rnd(8,472),False)
          Player[3]=New Ship(Rnd(8,632),Rnd(8,472),False)
     End
     
     Method OnUpdate()
     
          Local I:Int=0
          
          Repeat
               Player[I].Update()
               I+=1
          Until I>Players-1
     End
     
     Method OnRender()
     
          Cls
          DrawShips()
          '===================== that's what i was doing, works
          'Local I:Int=0
          
          'Repeat
           '    Player[I].Draw()
           '    I+=1
          'Until I>Players-1
          
        
     End
     
     
     Method DrawShips()
          For Local B:Ship = Eachin Playas
               B.Draw()
		End
     End
     
End

It does not work, unfornately. What am I doing wrong?

PS: 'Players' (in OnUpdate - not relevant though) is a global variable outiside Space class. I put it outside the class (I'd like to make it a field, but I couldn't access it from the ship class).

Afrobear

(Posted 2015) [#5]

Figured it out. Thanks! :)