Math for first sprite finally generating all the right numbers.

Platform/Apple/virtual/src/raycast/javascript/intcast.js

@@ -423,6 +423,9 @@ function intRenderSprites()
     var wRx = bSgnDx*bSgnCosT*pow2_w_w(wLogDx + wLogCosT) -
               bSgnDy*bSgnSinT*pow2_w_w(wLogDy + wLogSinT);
                             
+    if (sprite.index == debugSprite)
+      console.log("    wRx=$" + wordToHex(wRx));
+
     // If sprite is behind the viewer, skip it.
     if (wRx < 0) {
       if (sprite.index == debugSprite)
@@ -456,12 +459,18 @@ function intRenderSprites()
     // The constant below is cheesy and based on empirical observation rather than understanding.
     // Sorry :/
     var wX = bSgnRy * pow2_w_w(log2_w_w(wRy) - wLogDist + log2_w_w(252 / 8 / 0.44));  
-    if (sprite.index == debugSprite)
-      console.log("    wRx/256=" + (wRx/256.0) + ", wRy/256=" + (wRy/256.0) + ", wSize=" + wSize + ", wX=" + wX);
+    if (sprite.index == debugSprite) {
+      console.log("    wRy=$" + wordToHex(wRy) + ", wSqDist=$" + wordToHex(wSqDist) + 
+                  ", wLogDist=$" + wordToHex(wLogDist) + ", wLogSize=$" + wordToHex(wLogSize) + 
+                  ", wSize=$" + wordToHex(wSize));
+      //console.log("    wRx/256=" + (wRx/256.0) + ", wRy/256=" + (wRy/256.0) + ", wSize=" + wSize + ", wX=" + wX);
+    }
 
     // If no pixels on screen, skip it
     var wSpriteTop = 32 - (wSize >> 1);
     var wSpriteLeft = wX + wSpriteTop;
+    if (sprite.index == debugSprite)
+      console.log("    wX=$" + wordToHex(wX) + ", wSpriteTop=$" + wordToHex(wSpriteTop) + ", wSpriteLeft=$" + wordToHex(wSpriteLeft));
     var bStartTx = 0;
     if (wSpriteLeft < 0) {
       if (wSpriteLeft < -wSize) {
@@ -485,8 +494,12 @@ function intRenderSprites()
 
     // Calculate the texture bump per column. Result is really an 8.8 fix-point.
     var wTxColBump = pow2_w_w(wLog65536 - wLogSize);
+
+    // Calculate the depth index for blending with walls. The constant below is cheesy and 
+    // I'm not sure why it's needed. But it seems to keep things at roughly the right depth.
+    var bDepth = calcZ(wLogSize-75);
     if (sprite.index == debugSprite)
-      console.log("    bStartTx=" + bStartTx + ", wTxColBump=" + wTxColBump);
+      console.log("    bStartTx=$" + byteToHex(bStartTx) + ", wTxColBump=$" + wordToHex(wTxColBump) + ", bDepth=$" + byteToHex(bDepth));
 
     // Adjust from Apple II coordinates to PC coords (we render 8 pixels for each 1 Apple pix)
     wSpriteLeft *= 8;
@@ -499,9 +512,7 @@ function intRenderSprites()
     img.style.top = wSpriteTop+"px";
     img.style.width = wSize + "px";
     img.style.height = wSize + "px";
-    // The constant below is cheesy and I'm not sure why it's needed. But it seems to
-    // keep things at roughly the right depth.
-    img.style.zIndex = calcZ(wLogSize-75);
+    img.style.zIndex = bDepth;
   }
 }
 

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

@@ -77,8 +77,8 @@ wSqDist		= $AA
 wLogDist	= $AC
 wLogSize	= $AE
 wSize		= $B0
-wSpriteTop	= $B0
-wSpriteLeft	= $B2
+wSpriteTop	= $B2
+wSpriteLeft	= $B4
 
 ;---------------------------------
 ; The following are in aux mem...

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

@@ -30,7 +30,7 @@ NUM_COLS	= 63
 
 ; Useful constants
 W_LOG_256	= $0800
-W_LOG_65536	= $4000
+W_LOG_65536	= $1000
 W_LOG_VIEW_DIST = $0E3F
 
 ; Variables
@@ -795,8 +795,8 @@ spriteCalc: !zone
 	sta wSqDist+1		; save hi byte
 
 	; Calculate wLogDist = (log2_w_w(wSqDist) + wLog256) >> 1
-	txa			; hi byte in X
-	tya			; lo byte in A
+	tax			; stash hi byte in X
+	tya			; retrieve lo byte back to A
 	jsr log2_w_w		; convert to log space
 	tay			; set aside lo byte
 	txa			; work on hi byte
@@ -815,7 +815,7 @@ spriteCalc: !zone
 	sta wLogSize
 	tay			; lo byte where pow2 wants it
 	lda #>W_LOG_VIEW_DIST	; hi byte of constant
-	sbc wLogDist		; minus log dist
+	sbc wLogDist+1		; minus log dist
 	sta wLogSize+1
 	tax			; hi byte where pow2 wants it
 	jsr pow2_w_w		; get back from log space to normal space (in: Y=lo,X=hi, out: A=lo,X=hi)
@@ -934,7 +934,7 @@ spriteCalc: !zone
 	sec
 	sbc #75
 	sta depth
-	lda wLogSize
+	lda wLogSize+1
 	sbc #0
 	lsr
 	ror depth
@@ -948,7 +948,7 @@ spriteCalc: !zone
 	!if DEBUG { jsr .debug6 }
 
 .draw	; Okay, I think we're all done with calculations for this sprite.
-	brk	; would draw sprite here
+	rts	; would draw sprite here
 
 .negYX:				; subroutine to negate value in Y=lo,X=hi.
 	tya
@@ -994,20 +994,23 @@ spriteCalc: !zone
 	+prWord wLogSqRx
 	+prStr : !text "wLogSqRy=",0
 	+prWord wLogSqRy
+	+crout
 	+prStr : !text "wSqDist=",0
 	+prWord wSqDist
+	+prStr : !text "wLogDist=",0
+	+prWord wLogDist
+	+crout
 	+prStr : !text "wLogSize=",0
 	+prWord wLogSize
 	+prStr : !text "wSize=",0
 	+prWord wSize
+	+crout
 	+prStr : !text "wSpriteTop=",0
 	+prWord wSpriteTop
 	+crout
 	rts
 .debug5 +prStr : !text "wX=",0
-	+prX
-	+prA
-	+crout
+	+prXA
 	rts
 .debug6	+prStr : !text "bStartTx=",0
 	+prByte bStartTx