592 lines
10 KiB
ArmAsm
592 lines
10 KiB
ArmAsm
;
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; terrain
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;
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; Created by Quinn Dunki on 7/29/17
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;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; renderTerrain
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;
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; No stack operations permitted here!
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;
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; Trashes all registers
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;
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renderTerrain:
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FASTGRAPHICS
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lda #0
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sta SCRATCHL2 ; Row counter
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lda #$5f1f ; 4 Point stack to end of affected VRAM
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tcs ; 2
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sec
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lda #compiledTerrainEnd-VISIBLETERRAINWINDOW-4
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sbc mapScrollPos
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sta PARAML0
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renderTerrainLoop:
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; Note that DP register is normally $0000, so that is used as the BG/BG case
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lda #$0011 ; BG/FG
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ldx #$1111 ; FG/FG
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ldy #$1100 ; FG/BG
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jmp (PARAML0)
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renderRowComplete:
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lda PARAML0
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sec
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sbc #COMPILEDTERRAINROW
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sta PARAML0
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tsc
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clc
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adc #320
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tcs
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lda SCRATCHL2
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inc
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cmp lastCompiledTerrainY
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beq renderRowCont
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bcs renderTerrainDone
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renderRowCont:
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sta SCRATCHL2
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bra renderTerrainLoop
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renderTerrainDone:
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SLOWGRAPHICS
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rts
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; craterTerrain
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;
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; PARAML0 = X pos of center in pixels from logical left terrain edge
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; PARAML1 = Y pos of center in pixels from bottom terrain edge
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; Y = Radius of circle, in pixels (minimum is 3)
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;
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; Trashes SCRATCHL
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craterTerrain:
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SAVE_AX
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stz craterTerrainAccumulator
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lda #TERRAINWIDTH ; Convert X pos to terrain-right byte count
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sec
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sbc PARAML0
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sty SCRATCHL ; Center width in bytes
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sbc SCRATCHL
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sbc SCRATCHL
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and #$fffe ; Force even
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clc
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adc #terrainData
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sta PARAML0
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tya
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asl
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tay
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lda circleTable,y ; Look up circle data
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sta SCRATCHL
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tya ; Iterate over diameter words
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asl
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tay
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craterTerrainLoop:
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dey
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dey
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bmi craterTerrainDone
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tya
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clc
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adc PARAML0 ; Clip to terrain edges
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cmp #terrainData
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bmi craterTerrainDone
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cmp #terrainDataEnd
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bpl craterTerrainLoop
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lda (SCRATCHL),y ; Fetch circle Y value
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clc
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adc PARAML1 ; Convert to terrain-space
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bmi craterTerrainZero
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sta SCRATCHL2
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sec
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lda (PARAML0),y
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sbc SCRATCHL2
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bmi craterTerrainLoop
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; Circle value is lower, so use that
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clc
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adc craterTerrainAccumulator ; Track total crater material
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sta craterTerrainAccumulator
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lda SCRATCHL2 ; Replace terrain height with cratered value
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bmi craterTerrainZero ; Don't let it be negative
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sta (PARAML0),y
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bra craterTerrainLoop
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craterTerrainZero: ; Circle went negative so clip to 0
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lda #0
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sta (PARAML0),y
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bra craterTerrainLoop
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craterTerrainDone:
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lda #1
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sta terrainDirty
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RESTORE_AX
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rts
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craterTerrainAccumulator:
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.word 0
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; clipTerrain
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;
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; Saves the compiled terrain data that we overwrite into
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; a buffer at $E04000. We do this by shadowing the stack
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; to that area and pushing.
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;
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clipTerrain:
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SAVE_AXY
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; Shadow stack into $E04000 to save clipped data fast
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tsc
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sta STACKPTR
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lda #CLIPPEDTERRAINSTACK
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tcs
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sec
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lda #COMPILEDTERRAINROW*MAXTERRAINHEIGHT-4
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sbc mapScrollPos
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tay
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ldx #0
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clipTerrainLoop:
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lda compiledTerrain,y
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pha
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lda #$4cea ; NOP followed by JMP
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sta compiledTerrain,y
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iny
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iny
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lda compiledTerrain,y
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pha
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lda #renderRowComplete
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sta compiledTerrain,y
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tya
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sec
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sbc #COMPILEDTERRAINROW+2
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tay
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inx
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cpx lastCompiledTerrainY
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bcc clipTerrainLoop
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beq clipTerrainLoop
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; Put stack back where it belongs
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tsc
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sta clippedTerrainStackPtr
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lda STACKPTR
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tcs
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RESTORE_AXY
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rts
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; unclipTerrain
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;
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; Restores the compiled terrain data that we wrote
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; to a buffer at $E04000. We do this by mapping the stack
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; to $4000, then using stack-relative addressing to pull the data.
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; We can't pop the data because it's all stored in reverse.
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;
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; On first move-left unclip every second row is unclipped incorrectly
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unclipTerrain:
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SAVE_AXY
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phd
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lda #(CLIPPEDTERRAINSTACK & $f000)
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pha
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pld ; Point direct page at our clip data
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sec
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lda #COMPILEDTERRAINROW*MAXTERRAINHEIGHT-4
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sbc mapScrollPos
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tay
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sec ; Find stopping point for stack-relative addressing
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lda clippedTerrainStackPtr
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and #$0fff
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sbc #3 ; -3 for starting offset
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sta STACKPTR
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lda #$0fff-3 ; Start at the bottom of the stack
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tax
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unclipTerrainLoop:
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lda 2,x
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sta compiledTerrain,y
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iny
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iny
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lda 0,x
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sta compiledTerrain,y
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tya
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sec
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sbc #COMPILEDTERRAINROW+2
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tay
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dex ; Walk up the stack to reverse the data
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dex
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dex
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dex
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cpx STACKPTR ; When x hits the top of the stack, we're done
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bne unclipTerrainLoop
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pld
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RESTORE_AXY
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rts
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; compileTerrain
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;
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;
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;
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compileTerrain:
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SAVE_AY
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ldy #0
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lda #compiledTerrain
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sta PARAML0
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stz compileTerrainRowStart
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lda #TERRAINWIDTH
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sta compileTerrainRowEnd
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compileTerrainLoop:
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sty PARAML1
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jsr compileTerrainRow
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iny
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cpy #MAXTERRAINHEIGHT
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beq compileTerrainDone
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clc
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lda #COMPILEDTERRAINROW
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adc PARAML0
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sta PARAML0
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bra compileTerrainLoop
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compileTerrainDone:
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RESTORE_AY
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rts
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; compileTerrainChunk
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;
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; compileTerrainRowStart = Start column to compile (logical terrainData index)
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; compileTerrainRowEnd = Ending column to compile (logical terrainData index)
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;
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; Trashes A,Y, SCRATCHL, PARAML0, PARAML1
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;
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compileTerrainChunk:
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; Clamp chunk to left and right terrain edges
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lda compileTerrainRowStart
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bmi compileTerrainChunkClampZero
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compileTerrainChunkClampResume:
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lda compileTerrainRowEnd
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cmp #TERRAINWIDTH
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bcs compileTerrainChunkClampHigh
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compileTerrainChunkResume:
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ldy #0
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ldx #MAXTERRAINHEIGHT-1
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stx SCRATCHL
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sty PARAML0
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; Compute the start of memory affected
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lda #COMPILEDTERRAINROW
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sta PARAML1
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jsr mult16
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clc
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adc #compiledTerrain
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sta PARAML0
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compileTerrainChunkLoop:
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sty PARAML1
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jsr compileTerrainRow
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iny
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cpy SCRATCHL
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beq compileTerrainChunkDone
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clc
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lda #COMPILEDTERRAINROW
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adc PARAML0
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sta PARAML0
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bra compileTerrainChunkLoop
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compileTerrainChunkDone:
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rts
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compileTerrainChunkClampZero:
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stz compileTerrainRowStart
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bra compileTerrainChunkClampResume
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compileTerrainChunkClampHigh:
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lda #TERRAINWIDTH-1
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sta compileTerrainRowEnd
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bra compileTerrainChunkResume
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; compileTerrainRow
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;
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; PARAML0 = Start of compiled row data
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; PARAML1 = Row index
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; compileTerrainRowStart = Start column to compile (logical terrainData index)
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; compileTerrainRowEnd = Ending column to compile (logical terrainData index)
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;
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; Note: DA = PHX = FG/FG
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; 48 = PHA = FG/BG
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; 5A = PHY = BG/FG
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; 0B = PHD = BG/BG
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compileTerrainRow:
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SAVE_AXY
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lda compileTerrainRowStart ; Initialize horizontal counters
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lsr
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lsr
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and #%11111100 ; Word-align it
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tay
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asl ; Logical counter is 4x compiled counter
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asl
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tax
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lda compileTerrainRowEnd ; Convert end counter to compiled version
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lsr
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lsr
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and #%11111100
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sta compileTerrainRowEndCompiled
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compileTerrainColumnLoop:
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stz compileTerrainOpcode
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; Check column 0
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lda terrainData,x
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cmp PARAML1
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bcc compileTerrainColumn0BG
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beq compileTerrainColumn0BG
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; Column 0 is FG, so check column 1
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inx
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inx
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lda terrainData,x
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cmp PARAML1
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bcc compileTerrainColumn1BG
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beq compileTerrainColumn1BG
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; Columns 0 and 1 are FG/FG, so PHX
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lda #$00da
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compileTerrainColumn2:
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sta compileTerrainOpcode ; Cache results so far
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; Check column 2
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inx
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inx
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lda terrainData,x
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cmp PARAML1
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bcc compileTerrainColumn2BG
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beq compileTerrainColumn2BG
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; Column 2 is FG, so check column 3
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inx
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inx
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lda terrainData,x
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cmp PARAML1
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bcc compileTerrainColumn3BG
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beq compileTerrainColumn3BG
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; Columns 2 and 3 are FG/FG, so PHX
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lda compileTerrainOpcode
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ora #$da00
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compileTerrainColumnStore:
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sta (PARAML0),y
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inx
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inx
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iny
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iny
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cpy compileTerrainRowEndCompiled
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bne compileTerrainColumnLoop
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RESTORE_AXY
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rts
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compileTerrainColumn0BG:
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; Column 0 is BG, so check column 1
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inx
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inx
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lda terrainData,x
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cmp PARAML1
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bcc compileTerrainColumn01BG
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beq compileTerrainColumn01BG
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; Columns 0 and 1 are BG/FG, so PHA
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lda #$0048
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bra compileTerrainColumn2
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compileTerrainColumn01BG:
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; Columns 0 and 1 are BG/BG, so PHD
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lda #$000b
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bra compileTerrainColumn2
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compileTerrainColumn1BG:
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; Columns 0 and 1 are FG/BG, so PHY
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lda #$005a
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bra compileTerrainColumn2
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compileTerrainColumn2BG:
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; Column 2 is BG, so check column 3
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inx
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inx
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lda terrainData,x
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cmp PARAML1
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bcc compileTerrainColumn23BG
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beq compileTerrainColumn23BG
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; Columns 2 and 3 are BG/FG, so PHA
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lda compileTerrainOpcode
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ora #$4800
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bra compileTerrainColumnStore
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compileTerrainColumn23BG:
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; Columns 2 and 3 are BG, so PHD
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lda compileTerrainOpcode
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ora #$0b00
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bra compileTerrainColumnStore
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compileTerrainColumn3BG:
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; Columns 2 and 3 are FG/BG, so PHY
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lda compileTerrainOpcode
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ora #$5a00
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bra compileTerrainColumnStore
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compileTerrainOpcode:
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.word 0
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compileTerrainRowStart:
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.word 0
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compileTerrainRowEnd:
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.word 640
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compileTerrainRowEndCompiled:
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.word 0
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; prepareRowRendering:
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;
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; Set SCBs to match rendering mode of each terrain line
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;
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; Trashes SCRATCHL, SCRATCHL2
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;
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prepareRowRendering:
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SAVE_AXY
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ldx #199
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stz SCRATCHL2
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stz lastCompiledTerrainY
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prepareRowRenderingLoop:
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lda #0
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PLAYERPTR_Y
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sec
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lda playerData+GO_POSY,y
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sbc #GAMEOBJECTHEIGHT
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; cmp SCRATCHL2
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; bcc prepareRowRenderingCompileMode
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; beq prepareRowRenderingCompileMode
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; jsr enableFillMode
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; bra prepareRowRenderingLoopNext
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prepareRowRenderingCompileMode:
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jsr disableFillMode
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inc lastCompiledTerrainY
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prepareRowRenderingLoopNext:
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inc SCRATCHL2
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dex
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cpx #200-MAXTERRAINHEIGHT
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bne prepareRowRenderingLoop
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prepareRowRenderingDone:
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RESTORE_AXY
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rts
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; generateTerrain
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;
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; Trashes everything
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;
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generateTerrain:
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ldy #0
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ldx #0
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lda #terrainData
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sta SCRATCHL
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generateTerrainLoop:
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lda sineTable,x
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lsr
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lsr
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clc
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adc #30
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sta (SCRATCHL),y
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iny
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iny
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inx
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inx
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inx
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inx
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txa
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and #$03ff
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tax
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cpy #TERRAINWIDTH
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bne generateTerrainLoop
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; lda #1 ; Debug values
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; sta terrainData
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; lda #2
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; sta compiledTerrain-4
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rts
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compiledTerrain:
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.repeat COMPILEDTERRAINROW * MAXTERRAINHEIGHT
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.byte $42
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.endrepeat
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compiledTerrainEnd:
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clippedTerrainStackPtr:
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.word 0
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