Attaching shadows to active objects

[Cybert9]

I suspect this is really easy and I'm just too tired to figure it out (it's late). Help!

I have an active object (character) with multiple instances. I'm trying to attach a semi-transparent shadow to each instance. Obviously, the shadow needs to track the movement of the associated instance.

Here's what I've got so far:

Start of Frame
+ Spread 1 in Alt G of Active Object

Always
- Start loop "CreateShadows" NO Active Object times

On Loop "CreateShadows"
- Alterable Value G of Active Object = LoopIndex("CreateShadows") + 1
- Active Object NOT overlapping Shadow Object
+ Create Shadow Object at Active Object

On Loop "CreateShadows"
- Alterable Value G of Active Object = LoopIndex("CreateShadows") + 1
- Active object overlapping Shadow Object
+ Set Shadow Object x,y to Active Object x,y

The code above works fine... UNTIL two characters get close to each other and their shadows overlap other Active Objects. Then bad stuff happens.

Is there a better/easier way to do this?

[DistantJ]

Hi Cybert9. You're making it harder work than it needs to be! Just do this.

Give both the object and the shadow an Alterable Value called 'ID' (or just use Alt G like you did up there, I find it's better to name values).


To stick the shadows to the objects, it's very simple, just these two events:
* Start of Frame: Spread Value 1 in 'ID' of 'Object', Spread Value 1 in 'ID' of 'Shadow'
* 'ID' of 'Shadow' = 'ID' of 'Object': Set position of 'Shadow' to 0,0 from 'Object'


This works if you have the same number of shadows as you do objects, and you never destroy any of the objects. Add these two lines, though, and you can make it failsafe, to always ensure that you have the same number of shadows as objects, and that any shadow tied to an object which has been destroyed will be destroyed too!

* Number of 'Shadow' < Number of 'Object': Create 'Shadow' at (any position outside of the frame), Spread Value 1 in 'ID' of 'Shadow'
^ Note that we spread the values again, this is important! We need to spread the value again every time a new one is created (or set the value to number of shadows+1, but this is safer).
* Number of 'Shadow' > Number of 'Object' + Pick one of 'Object' at Random: Destroy 'Object', Spread Value 1 in 'ID' of 'Object', Spread Value 1 in 'ID' of 'Shadow'
^ We spread BOTH values again in this event, also important! It ensures we don't have a shadow/object ID mismatch when one is destroyed!


That's all you need! No fast loops at all! It just sticks the shadow to the object with the same ID as it. If you don't have the shadows for each object already in your frame and you notice shadows being 'created' (as in they quickly pop in one by one at the start if you don't have them in the frame already) after adding this code and you find it unpleasant, you can use a simple fast loop to create the right number of shadows (Number of 'Object' - Number of 'Shadow').

[MuddyMole]

Sorry, but that's totally wrong.
Just comparing IDs outside of a fastloop won't work. All that will do is pick the single newest "Object", and match the single "Shadow" with the same "ID" to it.
Also, you can't spread a value at the same time as creating a new "Object"/"Shadow". It will just set the newly created instance's ID to 1, and leave the rest as they were (so you'll end up with lots of objects all with the same ID).
Plus, that will only create/destroy a maximum of 1 shadow per frame - so if several are destroyed in quick succession, there will be the wrong number of shadows for a while.
Just forget spread values altogether - they're not needed here.

+ NObjects( "Shadow" ) < NObjects( "Player" )
-> Start fastloop "AddShadow", NObjects( "Player" ) - NObjects( "Shadow" ) times

+ On loop "AddShadow"
-> Create Shadow at 0,0

+ NObjects( "Shadow" ) > NObjects( "Player" )
-> Start fastloop "DelShadow", NObjects( "Shadow" ) - NObjects( "Player" ) times

+ On loop "DelShadow"
+ Shadow: Pick one at random
-> Shadow: Destroy

+ Always
-> Shadow: Set position at 0,0 from Player


You can actually skip the first 4 lines at just say "Always: Set Shadow position to 0,0 from Player" as long as you always create/destroy a shadow object every time you create/destroy a player.

[Stephen]

There is also a Shadow extension.

[DistantJ]

Sorry, but that's totally wrong.
Just comparing IDs outside of a fastloop won't work. All that will do is pick the single newest "Object", and match the single "Shadow" with the same "ID" to it.

Then how come I use it all the time and it works perfectly? You're overcomplicating it.

[MuddyMole]

It's probably like I said - the IDs all end up the same, so they become irrelevant (it's just like using an "always" condition, which is what I suggested). Just to demonstrate: https://skydrive.live.com/redir.aspx...094271BBDA!131

And I'm not overcomplicating it - I'm making it simpler, by not messing around with spread values for no reason.
The extra part with the fastloops is just to fix a bug that may or may not even be noticeable - it depends on what other events you have.

[gkinfinity]

Yeah you actually don't need spread values to accomplish this