looping through a type backwards?

Blitz3D Forums/Blitz3D Programming/looping through a type backwards?

Pongo

(Posted 2005) [#1]

ok,... stupid question here but I hope someone can help. This is a perfect example why artists should not try to program. By the way,... this is all 2d images, so when I refer to a sprite I mean a bitmap,... not a 3d sprite.

I need to be able to loop through a type backwards, or change the way I am doing things. Right now I have several sprites moving around, and each loop through, I check if they are being dragged by the mouse, then draw them at their position. All of this is working great, with one exception. I have them ordered from front to back based on y position, and when I loop through them it is from back to front (the way I want to draw them) The dragging, however grabs the first one found, which can be behind another one. This is very unnatural and I'd like to avoid it. If I could loop through them backwards it would work fine.

It would also be nice to be able to draw the sprite and check the drag in the same loop, so I don't have to loop through twice (once each way)

any ideas?

thanks.

BlackD

(Posted 2005) [#2]

look up the BEFORE command.

my.token = last token
checkclick()
for i = 1 to (numoftokens-1)
token = before token
checkclick()
next

Pongo

(Posted 2005) [#3]

Yea, that would work fine.

I guess what I'm really asking though, is if there is a way to not have to loop through twice? Once to check for dragging, and once to draw the images in the right order, since I need to draw them from back to front, yet check them from front to back.

The only thing I've thought of is making an array of types that I can sort through like (pseudocode):

for loop = i to count
check if dragging object(count-i)
draw image object(i)
next

but that is not very good since the number of objects will be changing a lot.

or is looping through twice simply the way to do it?

WolRon

(Posted 2005) [#4]

Hard to say without seeing some code. I don't know enough about your situation.

Jeppe Nielsen

(Posted 2005) [#5]

To loop backwards:

t.mytype=last mytype

While t<>null

DrawImage t\image,0,0
t=before t

Wend

TomToad

(Posted 2005) [#6]

you could just set up a pointer and update it whenever you come across one that's under the mouse, then when done looping through, you'll then have the pointer at the last instance of the type. I'm sure that didn't make any sense, so here's some code illustrating it.

For t.mytype = Each mytype
 If MouseOverSprite() Then drag.mytype = t.mytype
 DrawImage t\image,t\x,t\y
Next

DragSprite(drag.mytype)

Techlord

(Posted 2005) [#7]

Pongo

You could also INSERT the sprite BEFORE the previous one upon creation, and thus use FOR...EACH like normal.

t.mytype = New mytype
Insert t Before First mytype

For this.mytype = Each mytype
;do something to 'this'
Next

This will insert the Sprite Before the First one in the collection, making it the first one in the collection.

Pongo

(Posted 2005) [#8]

Thanks guys,... I think TomToad's idea is what I needed to do.

Pongo

(Posted 2005) [#9]

...

edit: removed non-working code,... figured out what I was doing wrong. Thanks again for the help above.