fill in scanlines during tiering

mandel.s

@@ -1201,6 +1201,10 @@ shift_loop:
     jmp shift_loop
 shift_done:
 
+    ldy fill_level
+    ldx fill_masks,y
+    inx
+
     ; pixel_offset = temp >> 2
     lda temp
     lsr a
@@ -1208,12 +1212,25 @@ shift_done:
     sta pixel_offset
     tay
 
+draw_pixel:
     ; read, mask, or, write
     lda (pixel_ptr),y
     and pixel_mask
     ora pixel_color
     sta (pixel_ptr),y
 
+    dex
+    beq done
+    clc
+    lda #40
+    adc pixel_ptr
+    sta pixel_ptr
+    lda #0
+    adc pixel_ptr + 1
+    sta pixel_ptr + 1
+    jmp draw_pixel
+
+done:
     rts
 .endproc
 

todo.md

@@ -11,8 +11,6 @@ things to try:
 
 * y-axis mirror optimization
 
-* try filling in the extra scanlines on 4x4 and 2x2 tiering
-
 * extract viewport for display & re-input via keyboard
 
 * fujinet screenshot/viewport uploader