Items on guardians´ paths

[Jet Set Willie]

As I have mentioned that as I haven´t played much the most of JSW homebrews, I may have invented the wheel few times once again. I don´t know if this is known already, so I will mention this, just in case.

As any guardians with the same colour as Willy will automatically collect any items on their paths, you can prevent this by defining a blank guardian with different colour than that particular guardian and placing it so that it will "mask" the item on guardian´s path. The guardian will not collect the item then. 🙂 Of course it will affect the guardian´s colour or any cells touching it, but if you don´t mind that, this may help your room planning. 😊

Edited October 10 by Jet Set Willie

[Spider]

It works in reverse too (at least I recall trying this once) if you place an invisible item in the path of a white guardian or an arrow , said item is collected for you.

Good one is the 'bug fix' to move the object from First Landing to Hall, its not got a shape defined. Moving an arrow to collect it would work.

From the disassembly:

93EC     LD A,(DE)     Pick up the current attribute byte at the item's location
93ED     AND $07     Is the INK white (which happens if Willy is touching the item, or the room's background tile has white INK, as in Swimming Pool)?
93EF     CP $07
93F1     JR NZ,$9430     Jump if not

Another way of looking at it, from Basic although this misses a lot out and makes some assumptions:

IF ATTR (x,y) = 7 THEN collect item

^ We are assuming here x,y is the location of the item on the screen and that we have black paper and white (non bright) ink aka colour code 7 , if it was bright it would be 71 (decimal)

Its seen in Swimming Pool as mentioned. The easy fix for that is to simply change the background ink to non white, green seems appropriate as Orangery is above.

[Jet Set Willie]

Thank you, but how I can place an invisible item? And how to place it the way that it will be collected by a guardian? By letting item´s Ink pixels to be same as Paper doesn´t help. By placing an "empty" guardian (no Ink pixels) doesn´t help either. I tried an "empty" item without pixels, too.

 

[Norman Sword]

Several incorrect assumptions. The game logic only allows "the ITEM draw logic" to collect ITEMS. Other logic can leave colour that "the ITEM draw logic"  will react to.

So sprites can not collect an item
Background colour will not collect an item
Arrows do not collect items

All the above do is colour in the ink cells and that allows "the ITEM draw logic"  to assume when it detects white that Willy is over the ITEM, and then "the ITEM draw logic" will collect it.

To have an invisible item. All that is needed is to define a graphic with no pixels present. "The ITEM draw logic"  will draw the invisible item. If A white sprite/an arrow or Willy walks over the item. Then the fact that white is now present in the square where the item is defined is enough for "the ITEM draw logic" to collect the invisible item.
 

Edited October 12 by Norman Sword
transposition of letters. Often called spelling mistoks

[Jet Set Willie]

Thank you, both of you. 🙂 Norman´s explanation made this very clear. 🙂 

I am not sure, what I did wrong in my previous try, but now the invisible item worked. 🙂 

[jetsetdanny]

On 10/10/2024 at 7:00 AM, Jet Set Willie said:

you can prevent this by defining a blank guardian with different colour than that particular guardian and placing it so that it will "mask" the item on guardian´s path.

[without trying to do it in a game] Won't this prevent Willy from collecting the item in question?

[Jet Set Willie]

You´re right, I was just about to quit my room tests, so I didn´t actually try, as previously Willy was able to collect an item masked by an "empty" guardian. Now I understand it was possible because those "empty" guardians were moving, so they didn´t mask the item all the time.

I am sorry for posting a not working example. But perhaps somebody could use this as a room idea about items what are possible to collect only in certain moments because of some invisible force?😉