Using Different Graphic Based on Direction

[Heroes & Shadows]

I have the following setup:

; player graphic
PlayerGraphic
PlayerDirectionUpGraphic
	.byte #%00111100
	.byte #%01111110
	.byte #%11000001
	.byte #%10111111
	.byte #%11111111
	.byte #%11101011
	.byte #%01111110
	.byte #%00111100

PlayerDirectionDownGraphic
	.byte #%00111100
	.byte #%01111110
	.byte #%11000001
	.byte #%10111111
	.byte #%11111111
	.byte #%11101011
	.byte #%01111110
	.byte #%00111100

PlayerDirectionLeftGraphic
	.byte #%00111100
	.byte #%01111110
	.byte #%11000001
	.byte #%10111111
	.byte #%11111111

And a ram variable:

PlayerDirection     .ds 1

With equates as follows:

DIRECTION_UP              equ 1
DIRECTION_DOWN       equ 2
DIRECTION_LEFT          equ 3
DIRECTION_RIGHT       equ 4

What is the best way to handle changing the sprite being displayed based on the "direction" the player is facing?

 

Sent from my LG-M150 using Tapatalk

[nsn]

First redefine your directions to start at 0 - saves a lot of unnecessary code and even more unnecessary religious discussions with LUA programmers

 

Then create a table of pointers to your graphics:

TBL_GFX_PTR_LO:
    .byte <(PlayerDirectionUpGraphic)
    .byte <(PlayerDirectionDownGraphic)
    .byte <(PlayerDirectionLeftGraphic)
    .byte <(PlayerDirectionRightGraphic) 

we need two bytes for a sprite pointer:

    PlayerGfxPtr ds 2

each frame we initialise said pointer (first HI- then LO-byte):

    lda #>(PlayerDirectionUpGraphic)
    sta PlayerGfxPtr+1
    ldy PlayerDirection
    lda TBL_GFX_PTR_LO,y
    sta PlayerGfxPtr
     

now, in our kernel, we can load from that pointer:

    lda (PlayerGfxPtr),y
    sta GRP0 

(I'm writing this code from memory, be wary)