GSCats/terrain_e1.s
blondie7575 f599267718 Fixed compiled terrain rendering
I thought it was working after the merging with fill mode, but it actually wasn’t. Should be now. Using only compiled rendering as of this commit.
2018-07-24 18:43:41 -07:00

298 lines
4.9 KiB
ArmAsm

;
; terrain (in E1 bank)
;
; Fill-mode terrain rendering code snippets
; that live in bank E1 for maximum speed.
;
; Created by Quinn Dunki on 7/29/17
;
.include "equates.s"
.include "macros.s"
UNRENDERCACHESTACK = $7ff ; Stack downwards from bottom of VRAM. Mirrored from $01 into $E1!
OP16
.org $800
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; renderTerrainSpans:
;
;
renderTerrainSpans:
SAVE_AXY
SAVE_DBR
FASTGRAPHICS
lda #UNRENDERCACHESTACK ; Prepare unrender cache
tcs
lda #MAXTERRAINHEIGHT-1
sec
sbc lastCompiledTerrainY
beq renderTerrainRowSpansSkip ; All terrain needs compiled rendering
renderTerrainSpansLoop:
sta PARAML1
; Find row data
lda PARAML1
asl ; Shifts must match SPANROWBYTES
asl
asl
asl
asl
tay
lda terrainSpanData,y
sta SCRATCHL ; Track span color
; Find VRAM row
lda PARAML1
asl
tax
lda vramRowInvertedSpanLookup,x
tax
adc #160
sta PARAML0 ; Watch for end of VRAM row
; Find span that intersects left logical edge
lda #0
clc
renderTerrainRowSpansFindLeftLoop:
adc terrainSpanData+2,y
cmp leftScreenEdge
bpl renderTerrainRowSpansFoundLeft
iny
iny
sta CACHEDATA
lda SCRATCHL
eor #%110000 ; Toggle span color cache
sta SCRATCHL
lda CACHEDATA
bra renderTerrainRowSpansFindLeftLoop
renderTerrainRowSpansFoundLeft:
sec
sbc leftScreenEdge ; A now holds remainder of leftmost span
; and Y points to leftmost span
renderTerrainRowSpansLoop:
sta SCRATCHL2
; Set fill mode byte for this span
lda SCRATCHL
sta VRAMBANK,x
; Cache the index we wrote to so we can erase later
phx
; Advance to end of span
clc
txa
adc SCRATCHL2
cmp PARAML0
bpl renderTerrainRowSpansDone
tax
; Prepare for next span
iny
iny
lda SCRATCHL
eor #%110000 ; Toggle span color cache
sta SCRATCHL
lda terrainSpanData+2,y
bra renderTerrainRowSpansLoop
renderTerrainRowSpansDone:
lda PARAML1
dec
bne renderTerrainSpansLoop
pea 0 ; Null-terminate the unrender cache
renderTerrainRowSpansSkip:
SLOWGRAPHICS
RESTORE_DBR
RESTORE_AXY
rtl
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; unrenderTerrainSpans:
;
;
unrenderTerrainSpans:
SAVE_AXY
SAVE_DBR
phb
pea $e1e1 ; Work entirely in bank E1 for all local read/writes
plb
plb
ldy #UNRENDERCACHESTACK-1
unrenderTerrainSpansLoop:
lda 0,y
beq unrenderTerrainSpansDone
tax
lda #0
sta a:0,x
dey
dey
bra unrenderTerrainSpansLoop
unrenderTerrainSpansDone:
plb
RESTORE_DBR
RESTORE_AXY
rtl
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; compileTerrainSpans:
;
;
compileTerrainSpans:
pha
SAVE_DBR
lda #0
compileTerrainSpansLoop:
sta PARAML1
jsr compileTerrainSpansRow
lda PARAML1
inc
cmp #MAXTERRAINHEIGHT
bne compileTerrainSpansLoop
RESTORE_DBR
pla
rtl
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; compileTerrainSpansRow:
;
; PARAML1 = Row index (bottom relative)
;
; Trashes SCRATCHL
;
compileTerrainSpansRow:
SAVE_AXY
lda PARAML1
asl ; Shifts must match SPANROWBYTES
asl
asl
asl
asl
clc
adc #terrainSpanData
sta SCRATCHL
ldy #0
ldx #TERRAINWIDTH-2
lda terrainDataFar,x ; Figure out start value for row
cmp PARAML1
bcs compileTerrainSpansRowInitGreen
compileTerrainSpansRowInitBlack:
lda #$0010 ; First span is black
sta (SCRATCHL) ; Initialize the row
inc SCRATCHL
inc SCRATCHL
ldy #-1
compileTerrainSpansRowBlackStart:
iny
compileTerrainSpansRowBlackLoop:
lda terrainDataFar,x
cmp PARAML1
bcs compileTerrainSpansBlackEnd
dex
dex
iny
cpx #-2
bne compileTerrainSpansRowBlackLoop
compileTerrainSpansBlackEnd:
tya ; Store this span's length
sta (SCRATCHL)
inc SCRATCHL
inc SCRATCHL
dex ; Begin searching for next span
dex
cpx #0
bmi compileTerrainSpansRowDone
ldy #0
bra compileTerrainSpansRowGreenStart
compileTerrainSpansRowDone:
RESTORE_AXY
rts
compileTerrainSpansRowInitGreen:
lda #$0020 ; First span is green
sta (SCRATCHL) ; Initialize the row
inc SCRATCHL
inc SCRATCHL
ldy #-1
compileTerrainSpansRowGreenStart:
iny
compileTerrainSpansRowGreenLoop:
lda terrainDataFar,x
cmp PARAML1
bcc compileTerrainSpansGreenEnd
dex
dex
iny
cpx #-2
bne compileTerrainSpansRowGreenLoop
compileTerrainSpansGreenEnd:
tya ; Store this span's length
sta (SCRATCHL)
inc SCRATCHL
inc SCRATCHL
dex ; Begin searching for next span
dex
cpx #0
bmi compileTerrainSpansRowDone
ldy #0
bra compileTerrainSpansRowBlackStart
terrainSpanData:
.repeat MAXTERRAINHEIGHT
.word 0 ; Start value (0=BG)
.repeat MAXSPANSPERROW
.word 0 ; Length (in bytes)
.endrepeat
.endrepeat
vramRowInvertedSpanLookup = $16C0 ; This table is copied to here by the loader
.export renderTerrainSpans
.export unrenderTerrainSpans
.export compileTerrainSpans
; Suppress some linker warnings - Must be the last thing in the file
.SEGMENT "ZPSAVE"
.SEGMENT "EXEHDR"
.SEGMENT "STARTUP"
.SEGMENT "INIT"
.SEGMENT "LOWCODE"