ACag's Routine

#define renderDistance 10   ; adjust this to change the render distance
#define priorAngle rcStack+2    ; 1 byte


engine_raycaster_Init:
    ld de,SlendMapPtr
_raycaster_loopobject
    push de
        inc de
        ld a,(de)
        ld hl,playerPosY
        sub (hl)
        ld c,a
        dec de
        ld a,(de)
        ld hl,playerPosX
        sub (hl)
        call _getDistance
        ld de,(renderDistance)
        sbc hl,de \ add hl,de
        jr nc,_raycaster_nextobject
        ld a,l
        push af                         ; distance
            ld a,(de)
            ld hl,playerPosX
            sub (hl)
            ld b,a
            inc de
            ld a,(de)
            ld hl,playerPoxY
            sub (hl)
            call a_div_b
            call arctan_88
            ld hl,playerDirection
            sub (hl) \ add a,5 \ cp 11 \ jr nc,_raycaster_nextobject
            push af                     ; angle
                inc de
                ld a,(de)               ; a = object type id, use to pull sprite
                ld hl,spriteLUT \ add a,a \ ld c,a \ ld b,0
                add hl,bc
                ld c,(hl) \ inc hl \ ld b,(hl) \ ld hl,spriteStart \ add hl,bc      ; hl = PTR to sprite layers
            pop af      ; angle back out
            rla \ rla \ rla
            ld d,a                      ; we got our x-coord
            ld b,a \ ld a,20 \ add a,b \ ld e,a     ; we got our y-coord
        pop af                          ; distance back out
;fixed from "ld a,c"
        ld c,a \ ld b,0
        ld hl,distanceLUT
        add hl,bc
        ld a,(hl)                       ; distance -> scale factor, out a
        call render_ScaledSprite
_raycaster_nextobject
    pop de
        inc de
        inc de
        inc de
    ld a,(de)
    inc a
    jr nz_raycaster_loopobject
    ret

spriteLUT:
; pretend there is data here
distanceLUT:
.db $00,$F2,$E5,$D8,$CC,$BF,$B2,$A5,$99,$8C,$7F


render_ScaledSprite:
;   in: hl = ptr to sprite, de = coords of sprite, a = scale factor
;   scalespr.inc
; putScaledSprite reqs: hl=sprite PTR, de=(x,y), bc=(height,width/8), a=scale factor ($01 to $00 <=> 0.4% to 100%)
; in the original routine, it wrote to plotsscreen (ld de,plotSScreen). I changed its write-to to iy, so that I could call the routine twice (ld de,iy).
    ld b,(hl)
    inc hl
    ld c,(hl)
    inc hl
    ld iy,frontBuffer1
    push de
        push af
            push hl
                push bc
                    call putScaledSprite
                pop bc
            pop hl
            ; jump hl to start of back buffer sprite
            ld e,c      ; bc: c is width (in bytes), b is height
            ld d,0
            push bc
            __get2ndLayer_loop:
                add hl,de
                djnz __get2ndLayer_loop
            pop bc
        pop af
    pop de
    ld iy,frontBuffer2
    call putScaledSprite
    ret