Actually started debugging the sprite math.

Platform/Apple/virtual/src/raycast/render.s

@@ -625,7 +625,9 @@ spriteCalc: !zone
 	sbc #>W_LOG_256		; subtract wLog256
 	sta wLogCosT+1		; store hi byte
 
-	; Calculate wDx = spriteX - playerX, as abs value and a sign bit
+	!if DEBUG { jsr .debug1 }
+
+	; Calculate wLogDx = log2_w_w(spriteX - playerX), as abs value and a sign bit
 	lda spriteX		; calculate spriteX - playerX
 	sec
 	sbc playerX
@@ -641,7 +643,7 @@ spriteCalc: !zone
 	sta wLogDx
 	stx wLogDx+1
 
-	; Calculate wDy = spriteY - playerY, as abs value and a sign bit
+	; Calculate wLogDy = log2_w_w(spriteY - playerY), as abs value and a sign bit
 	lda spriteY		; calculate spriteX - playerX
 	sec
 	sbc playerY
@@ -657,6 +659,8 @@ spriteCalc: !zone
 	sta wLogDy
 	stx wLogDy+1
 
+	!if DEBUG { jsr .debug2 }
+
 	; Calculate wRx = bSgnDx*bSgnCosT*pow2_w_w(wLogDx + wLogCosT) -
 	;                 bSgnDy*bSgnSinT*pow2_w_w(wLogDy + wLogSinT)
 	lda wLogDx		; start with lo byte
@@ -696,6 +700,8 @@ spriteCalc: !zone
 	adc wRx+1		; also hi byte
 	sta wRx+1
 
+	!if DEBUG { jsr .debug3 }
+
 	; if wRx is negative, it means sprite is behind viewer... we get out of school early.
 	bpl +
 	!if DEBUG { +prStr : !text "Sprite is behind viewer.",0 }
@@ -833,6 +839,8 @@ spriteCalc: !zone
 	inx			; bump hi byte
 +	stx wSpriteTop+1	; save hi byte
 
+	!if DEBUG { jsr .debug4 }
+
 	; Need X position on screen.
 	; The constant below is cheesy and based on empirical observation rather than understanding.
 	; Sorry :/
@@ -855,6 +863,8 @@ spriteCalc: !zone
 	jsr pow2_w_w		; back to normal space (in: Y=lo,X=hi, out: A=lo,X=hi)
 	; don't need to actually store wX -- it's only needed for spriteLeft below
 
+	!if DEBUG { jsr .debug5 }
+
 	; Calculate wSpriteLeft = wx + wSpriteTop
 	clc			; lo byte already in A from code above
 	adc wSpriteTop		; add to spriteTop (which if you think about it, is a function of dist just like spriteLeft)
@@ -935,6 +945,8 @@ spriteCalc: !zone
 	lsr
 	ror depth
 
+	!if DEBUG { jsr .debug6 }
+
 .draw	; Okay, I think we're all done with calculations for this sprite.
 	brk	; would draw sprite here
 
@@ -950,6 +962,62 @@ spriteCalc: !zone
 	inx
 +	rts
 
+	; Code for debugging sprite math
+!if DEBUG {
+.debug1	+prStr : !text "bSgnSinT=",0
+	+prByte bSgnSinT
+	+prStr : !text "wLogSinT=",0
+	+prWord wLogSinT
+	+prStr : !text "bSgnCosT=",0
+	+prByte bSgnCosT
+	+prStr : !text "wLogCosT=",0
+	+prWord wLogCosT
+	+crout
+	rts
+.debug2	+prStr : !text "bSgnDx=",0
+	+prByte bSgnDx
+	+prStr : !text "wLogDx=",0
+	+prWord wLogDx
+	+prStr : !text "bSgnDy=",0
+	+prByte bSgnDy
+	+prStr : !text "wLogDy=",0
+	+prWord wLogDy
+	+crout
+	rts
+.debug3	+prStr : !text "wRx=",0
+	+prWord wRx
+	+crout
+	rts
+.debug4	+prStr : !text "wRy=",0
+	+prWord wRy
+	+prStr : !text "wLogSqRx=",0
+	+prWord wLogSqRx
+	+prStr : !text "wLogSqRy=",0
+	+prWord wLogSqRy
+	+prStr : !text "wSqDist=",0
+	+prWord wSqDist
+	+prStr : !text "wLogSize=",0
+	+prWord wLogSize
+	+prStr : !text "wSize=",0
+	+prWord wSize
+	+prStr : !text "wSpriteTop=",0
+	+prWord wSpriteTop
+	+crout
+	rts
+.debug5 +prStr : !text "wX=",0
+	+prX
+	+prA
+	+crout
+	rts
+.debug6	+prStr : !text "bStartTx=",0
+	+prByte bStartTx
+	+prStr : !text "wTxColBump=",0
+	+prWord wTxColBump
+	+prStr : !text "depth=",0
+	+prByte depth
+	rts
+}
+
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