Good Programming Habits

Blitz3D Forums/Blitz3D Programming/Good Programming Habits

PaulJG

(Posted 2003) [#1]

I've written this little routine that creates a terrain mesh for me, but at the mo its got hardcoded variables.. I'd like to seperate it from my main program loop and make it into a function that I could call, whenever its needed. But, I'm not too sure how to go about it.

Here's some snippets of the code:

Global terrain_pivot=CreatePivot()
Global mesh_land=CreateMesh(terrain_pivot)
Global surf=CreateSurface(mesh_land)

I need these, but I realize I cant put them into a function.

Then comes the rest of the code..

...
AddVertex surf,x+cenx#,y+ceny#,0,0,0,0 0
AddVertex surf,x+cenx#,(y+1.0)+ceny#,0, 1,0, 0
...

As you can see I'm using the global handle surf, which is fine if I'm only calling the function once - but if I want to use it twice ?.

Ideally, I'd just like to call the function, like this:

global terrainpatch=make_terrain(terrainpatch)

And that would be that !. But I'm just alittle puzzled how I can go about it.

Any Help Guys ?...pretty please !.

Bot Builder

(Posted 2003) [#2]

I'm not sure what you mean by terrainpatch in the function call, but I was thinking somthing like this:

global terrainpatch=make_terrain(terrainpatch) 

function make_terrain()
 mesh_land=CreateMesh(terrain_pivot)
 surf=CreateSurface(mesh_land)
 ...
 AddVertex surf,x+cenx#,y+ceny#,0,0,0,0 0
 AddVertex surf,x+cenx#,(y+1.0)+ceny#,0, 1,0, 0
 ...
 return mesh_land
end function

;then in the case that you wanted to get the surface again,

surf=getsurface(mesh,1)

BlitzSupport

(Posted 2003) [#3]

You need to use types, and want to be doing this kind of thing (note that this code won't run on its own!):


; Terrain 'object'... add whatever fields you require...

Type Terrain
    Field terrain_pivot
    Field mesh_land
    Field surf
    Field number ; Example field to receive parameter passed in function below...
End Type

; Function to create Terrain object -- note return type!

Function CreateNewTerrain.Terrain (example)

    t.Terrain = New Terrain

    t\terrain_pivot = CreatePivot ()
    t\mesh_land = CreateMesh (t\terrain_pivot)
    t\surf = CreateSurface (t\mesh_land)
    t\num = example

    ; Etc...

    Return t

End Function

; D E M O . . .

; Get a pointer to the object that is created and returned...

test.Terrain = CreateNewTerrain (1)

Print test\num ; Would be '1'...

; Move the resulting terrain...

MoveEntity test\terrain_pivot, 0, 10, 0 ; Etc...

Let me know if any of that needs further explanation!

PaulJG

(Posted 2003) [#4]

Thanks Guys, just what I was after.

James, I'm a reasonable C coder that can use structures - but for some reason I just cant get my head around blitz'es types !?. (all this '.' and '\' !)

Cheers for the example code. ;)

soja	(Posted 2003) [#5]

James, I'm a reasonable C coder that can use structures - but for some reason I just cant get my head around blitz'es types !?. (all this '.' and '\' !)

There is a trick to it. Once you realize that (a) '.' isn't the member operator ('\' is), and (b) the type designation always comes AFTER the variable name, it gets a lot easier.

e.g.
int: a%
float: a#
string: a$
custom: a.custom <-- '.' is type declaration

and then the neumonic for remembering \ is that \ is analogous to a directory. WHen you want to get at a field that "in" a certain type, use '\'.

a\field1 <-- this type is already instantiated