Problem with List

Monkey Forums/Monkey Programming/Problem with List

Rone	(Posted 2012) [#1]

Hallo,

I wonder if there is any common way of iterating through an list and inserting an new node at a specific position...without changing the List class?

First of all its very annoying that there's no way to retrieve the Head node, since HeadNode.GetNode returns null per default...so I changed it for testing, that it returns Self...

Strange thing is, that my code behave different when using List._head or List.FirstNode(). List._head seems to work, but List.FirstNode() chrashes although they returns the same reference..

Here's the sample code..convertion from miniB3D's 'RenderListAdd(mesh:TMesh,List:TList)'

Class MeshList extends List<Mesh>

	Method new(cam:Camera, Meshes:List<Mesh>)
		For Local mesh:= eachin Meshes
			if mesh.Visible And mesh.Material.Alpha > 0.001 Then 
				if cam.EntityInView(mesh) Then 
					Add(cam, mesh)
				End 
			EndIf
		Next
	End
	
	Method Add:list.Node<Mesh>(cam:Camera, mesh:Mesh)
	
		' if Order>0, drawn first (will appear at back of scene)
		' if Order<0, drawn last (will appear at front of scene)
		
		Local head:= _head'FirstNode()
		Local node:= _head'FirstNode()
		
		if mesh.Order > 0 Then 
			' add entity to start of list
			' entites with order>0 should be added to the start of the list
			' cycle fowards through list until we've passed all entities with order>0, or if entity itself has order>0,
			' it's own position within entities with order>0
			Repeat
				node=node.NextNode
			Until node=head Or Mesh(node.Value).Order <= mesh.Order 
			
			Return New list.Node<Mesh>( node.NextNode,node, mesh ) ' check order
			
		ElseIf mesh.Order < 0 then
			' add entity to end of list
			' only entites with order<=0 should be added to the end of the list
			' cycle backwards through list until we've passed all entities with order<0, or if entity itself has order<0,
			' it's own position within entities with order<0
			Repeat
				node=node.PrevNode
			Until node=head Or Mesh(node.Value).Order>=mesh.Order 
			
			Return New list.Node<T>( node,node.PrevNode,mesh )' check order
		EndIf
		
		if mesh.Material.Alpha < 0.01 or mesh.Material.Blending <> MATERIAL_BLEND_SOLID Then 
			' add alpha entities to near end of list
			' before entities with order<0
			mesh.AlphaOrder =  cam.DistanceSquared(mesh)
			Repeat 
				node=node.PrevNode
				if node = head Then Exit 
			Until Mesh(node.Value).Order>=0 And (Mesh(node.Value).AlphaOrder>=mesh.AlphaOrder Or Mesh(node.Value).AlphaOrder=0.0)
			
			Return New list.Node<T>( node,node.PrevNode,mesh )' check order
		Else
			' normal entities - add to list at start - after entities with order>0
			Repeat
				node=node.NextNode
			Until node=head Or Mesh(node.Value).Order<=0
			
			Return New list.Node<T>( node.NextNode,node,mesh ) ' check order
		EndIf
	End

End

AdamRedwoods

(Posted 2012) [#2]

I wrote about Nodes and Node insertion in wikibooks (the quick answer is use the Node constructor):
http://en.wikibooks.org/wiki/Monkey/Language/Lists

As for miniB3D, the route I took is not to worry too much about mesh.order since you can sort the list according to order value when the user decides to order on their own using TEntity EntityOrder().

Plus, that ListEntityAdd() will go through the entire entity list. When you are doing large terrains and particles (2000+), this will start to eat time if you are adding/freeing multiple entities every frame. Better to Sort() a sublist after the camera does its frustum culling.

Side note: I've been working on a version of monkey+miniB3D that I hope to release end of this month. You can track my progress here:
http://monkeycoder.co.nz/Community/posts.php?topic=2212
I encourage others to take a crack at miniB3D as well, it's a great way to learn monkey.

Rone	(Posted 2012) [#3]

Thank you very much!

Added a dummy mesh before List.FirstNode() and checked for null...Works now :)

Better to Sort() a sublist after the camera does its frustum culling.

Using it only for testing/ prototyping...didn't meditate on fast scene management on mobile platforms yet...

I encourage others to take a crack at miniB3D as well, it's a great way to learn monkey.

Its definitely a great source for beginners when learning openGl, but its an architectural disaster with chunky issues in its design...[ ..not the brilliant B3D top part ;)] people should better take a crack at Ogre or reading professional blogs for example...

Did you encapsulate the openGL stuff in your miniB3D version, in order to support xna, for example?

AdamRedwoods

(Posted 2012) [#4]

Did you encapsulate the openGL stuff in your miniB3D version, in order to support xna, for example?

No, i'm trying not to deviate from minib3d too much to keep the simplicity.
I feel the community can add to it/modify it to their hearts pleasure once it's released, since I feel that's what most minib3d users do.