Avalon: Routine at 58032

58032: Copy room item event data into working buffer

Used by the routines at 52263, 52616 and 53403.

Input
A	Event number involving this object (stored at 60303) Also used for energy-affecting objects, e.g. orbs and mushrooms, 254 = energy drain, 253 = energy replenish

Uses room item event data sets at 32691 that will need checking for certain items/objects in the current room.

58032

LD C,A

Copy event number ID into C register

58033

LD A,(60116)

Horizontal position of object (high byte). This is 0 if object is on-screen. 1 means off-screen to the right, 255 means off-screen to the left.

58036

CP 0

If it's 0, it's on the current screen (viewport)

58038

JR NZ,58063

If not, this item is off-screen so no collisions/interactions with this object will need checking - jump straight to RET

58040

LD HL,(60077)

Pointer to the event data sets at 32691

58043

LD (HL),2

Set the first byte of the set to 2, which means the event will be checked for 2 game cycles, mainly in case items are moving around.

58045

INC HL

Move along one byte

58046

LD (HL),C

Byte 2 of set - the event/interaction identifier/value to check for this item

58047

INC HL

58048

LD A,(60115)

Byte 3 of set - item's horizontal screen position (in pixels)

58051

LD (HL),A

58052

INC HL

58053

LD A,(60114)

Byte 4 of set - item's vertical position (in pixels)

58056

LD (HL),A

58057

INC HL

The event table is dynamic - it can shrink/expand and is recaculated each frame, so put a 255 at the start of the next set to mark the end of item sets

58058

LD (HL),255

58060

LD (60077),HL

Restore the address pointer at the start of this next set

58063

RET