Avalon: Routine at E2B0

E2B0: Copy room item event data into working buffer

Used by the routines at CC27, CD88 and D09B.

Input
A	Event number involving this object (stored at EB8F) Also used for energy-affecting objects, e.g. orbs and mushrooms, 254 = energy drain, 253 = energy replenish

Uses room item event data sets at 7FB3 that will need checking for certain items/objects in the current room.

E2B0

LD C,A

Copy event number ID into C register

E2B1

LD A,($EAD4)

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.

E2B4

CP $00

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

E2B6

JR NZ,$E2CF

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

E2B8

LD HL,($EAAD)

Pointer to the event data sets at 7FB3

E2BB

LD (HL),$02

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.

E2BD

INC HL

Move along one byte

E2BE

LD (HL),C

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

E2BF

INC HL

E2C0

LD A,($EAD3)

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

E2C3

LD (HL),A

E2C4

INC HL

E2C5

LD A,($EAD2)

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

E2C8

LD (HL),A

E2C9

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

E2CA

LD (HL),$FF

E2CC

LD ($EAAD),HL

Restore the address pointer at the start of this next set

E2CF

RET