Sprite attributes (properties)

[enonod]

It would be very helpful IMHO if sprite collision (ability) could be turned on/off and still have the sprite visible and doing things. It would seem to me that it could save a lot of interrupts uneccessarily and could save a lot of testing code.

If this can be done already in some way I would be grateful to hear of it.

[agraham]

Erel has given me the go-ahead to produce a new version of the Sprite library which will be the next official release. Try the attached Sprite library version 1.21.

The changes over the current Sprite library are :-

Added a Sprite.ID property that lets you name or number a Sprite and so identify a particular Sprite returned as Sprite1 or Sprite2 in a collision.

Added a GameWindow.GetSpriteID(id) method that returns a reference to a Sprite with the specified ID. This can be assigned to a Sprite Value property to manipulate the Sprite.

Added a GameWindow.CheckSpriteCollisions boolean property. True (the default) checks for Sprite collisions, set to to False to stop Collisions occurring

Modified the Sprite.IntersectsPoint hit test to work properly (I hope!).

Post here any further changes you can think of.

[enonod]

Wow, thank you very much. I have not downloaded yet but had to reply with gratitude.

[enonod]

Thank you agraham and of course Erel for permission. I can confirm that the Intersection problem is now solved and it works correctly, pixel perfect!!

[enonod]

Not wishing to appear greedy, but will you please now explain how to get over the double event triggered by a collision when neither sprite is going to be deleted.
It appears (from an earlier post I made) that the system will not simply ignore it by counting two and then dealing with it. This would of course be what is commonly called the icing on the cake.

[enonod]

Sorry about the multi posts but I assume editing might not get noticed.
I have checked the new anti-collision and I believe there was a misunderstanding or reading.

...and still have the sprite visible and doing things

My original intention was that individual sprites could be prevented from being collideable via a Boolean property. It might be that say 10 sprites should never or perhaps only under certain conditions be permitted to collide.
To turn the collision mechanism off altogether is undoubtedly useful, but please could the original request (possibly badly explained) be considered?
It could be done now using your new ID and filtering it in the collision sub, I presume, but it doesn't prevent the collision sub being called and slowing the system down. Of course I don't know how this could possibly be done, but sprites do already have some properties and this could presumably be just one more???
[Edit]Sorry to be a bore but I tried this and I get the error Object must first be created.... The idea of all this is to do something to a specific sprite if it collides but not if it is some other sprite.

gw.s has been created as a sprite and works

s has been created as a sprite and works
s.ID="Fred" seems OK
spr1 has also been in use ok

Sub gw_collision
Spr1.value=gw.Sprite1

If spr1.ID<>"Fred" Then
spr1.Velocity=6
...

[agraham]

I am going to rewrite collisions later today or tomorrow so I'll look at it then.

Originally Posted by enonod

I get the error Object must first be created....

Those lines of code appear to work fine for me. Which object on which line?

[enonod]

I am going to rewrite collisions later today or tomorrow so I'll look at it then.

Thank you very much for that.

Sorry for not being clear... it refers to the first line in the collision sub
Spr1.value=gw.Sprite1
Spr1 has been in the objects list all along and not presented a problem.

[Edit] Profound apology... a typo, leaving in a comment marker. Works fine

[enonod]

Having got over the self inflicted error, I find that the following produces '0' on both labels.
The if is handled as true for either gw.sprite1 or 2 and the two id's are "cw" and "fred".
I cannot see that anything is wrong with the code, so I will leave it with you while you do your rewrite.

Sub gw_collision
label3.Text=gw.Sprite1.id
label4.Text=gw.Sprite2.id
Spr1.value=Gw.sprite2
If spr1.id <> "Fred" Then
spr1.Velocity=20
End If
End Sub

Thanks.

[agraham]

I'm afraid your code is wrong. Basic4ppc can't handle compound references to properties and methods like "gw.Sprite1.ID". The IDE doesn't error this but returns 0 or an empty string. The optimising compiler will however error it, though not with a helpful message. You need to use this code.

Sub gw_collision
  Spr1.value=Gw.Sprite1
  Spr2.value=Gw.Sprite2
  label3.Text=Spr1.ID
  label4.Text=Spr2.ID
   ...