Added crater clipping to terrain edges

gamemanager.s

@@ -22,21 +22,6 @@ beginGameplay:
 
 	; Generate, compile, and clip terrain
 	jsr generateTerrain
-
-;	lda #40
-;	sta PARAML0
-;	lda #30
-;	sta PARAML1
-;	ldy #12
-;	jsr craterTerrain
-
-;	lda #74
-;	sta PARAML0
-;	lda #30
-;	sta PARAML1
-;	ldy #16
-;	jsr craterTerrain
-
 	jsr compileTerrain
 	jsr clipTerrain
 

projectile.s

@@ -30,7 +30,7 @@ GRAVITY = $ffff	; 8.8 fixed point
 
 projectileTypes:		; Byte offsets into projectile type data structure
 	.word 50		; Damage
-	.word 12		; Crater radius
+	.word 40		; Crater radius
 	.word 0,0		; Padding
 
 PT_DAMAGE = 0

terrain.s

@@ -66,7 +66,6 @@ craterTerrain:
 	sbc PARAML0
 	sty SCRATCHL			; Center width in bytes
 	sbc SCRATCHL
-;	sbc SCRATCHL
 	and #$fffe				; Force even
 	clc
 	adc #terrainData
@@ -84,9 +83,18 @@ craterTerrainLoop:
 	dey
 	bmi craterTerrainDone
 
+	tya
+	clc
+	adc PARAML0				; Clip to terrain edges
+	cmp #terrainData
+	bmi craterTerrainDone
+	cmp #terrainDataEnd
+	bpl craterTerrainLoop
+
 	lda (SCRATCHL),y		; Fetch circle Y value
 	clc
 	adc PARAML1				; Convert to terrain-space
+	bmi craterTerrainZero
 	sta SCRATCHL2
 	lda (PARAML0),y
 	cmp SCRATCHL2
@@ -96,6 +104,11 @@ craterTerrainLoop:
 	sta (PARAML0),y
 	bra craterTerrainLoop
 
+craterTerrainZero:			; Circle went negative so clip to 0
+	lda #0
+	sta (PARAML0),y
+	bra craterTerrainLoop
+
 craterTerrainDone:
 	lda #1
 	sta terrainDirty
@@ -408,6 +421,7 @@ terrainData:
 	.repeat TERRAINWIDTH/2
 	.word 0
 	.endrepeat
+terrainDataEnd:
 
 compiledTerrain:
 	.repeat COMPILEDTERRAINROW * MAXTERRAINHEIGHT