duskos

commit eba4bd8efdde8a6310e24ed2160e2e1836623977
parent 6fcd3551b997e331c8adad8de3b8371e377dbbb0
Author: Virgil Dupras <hsoft@hardcoded.net>
Date:   Thu, 15 Dec 2022 09:31:58 -0500

emul/uxn/screen: implement fg/bg logic for pixels

Diffstat:
M
fs/emul/uxn/screen.fs
 | 
28
+++++++++++++++++++++++++---
M
fs/tests/manual/uxn/rect.tal
 | 
28
+++++++++++++++++++++-------

2 files changed, 46 insertions(+), 10 deletions(-)
diff --git a/fs/emul/uxn/screen.fs b/fs/emul/uxn/screen.fs
@@ -1,7 +1,23 @@
 \ Varvara screen implementation
 require /sys/draw.fs
+?f<< /lib/bit.fs
 ?f<< /emul/uxn/varvara.fs
 
+\ FG Mask: to properly handle FG/BG logic, we need to know which pixels are
+\ "filled" on the FG layer, that is, have a non-zero color. When it is, a draw
+\ operation on the BG layer will have no effect.
+\ Let's say, for now, that maximum supported resolution is 1024x768
+1024 768 * 8 / const FGMASKSZ
+create _fgmask FGMASKSZ allot
+
+: _fg' ( x y -- bit a )
+  scrwidth * + 8 /mod ( bit a ) _fgmask + ;
+: _fg! ( x y id -- )
+  >r _fg' dup c@ ( bit a n )
+  rot r> if bit1! else bit0! then ( a n )
+  swap c! ;
+: _fg? ( x y -- f ) _fg' c@ swap bit? ;
+
 \ example: $5678 for "r" means ID0=5 ID1=6 ID2=7 ID3=8
 : _extract ( systemrgb id -- rgb8 )
   3 -^ << << rshift $f and ( rgb4 ) 4 lshift ;
@@ -11,17 +27,23 @@ require /sys/draw.fs
   dup short@ r@ _extract ( 'r r8 )
   swap 1+ 1+ dup short@ r@ _extract ( r8 'g g8 )
   swap 1+ 1+ short@ r> _extract ( r8 g8 b8 ) rgbcolor ;
+: _drawpixel ( x y pixel -- )
+  3 and screencolor ( x y color )
+  rot> pixel' pixel! ;
 
 : screendei ( dev port -- c ) 2drop 0 ;
 : screendeo ( dev port -- ) case ( dev ) \ V1=case
     $e of = >r \ V2=dev
-      $8 r@ devshort@ ( x ) $a r@ devshort@ ( x y ) pixel' ( a )
-      $e r> Device dat + c@ 3 and screencolor ( a color )
-      swap pixel!
+      $8 r@ devshort@ ( x ) $a r@ devshort@ ( x y )
+      $e r> Device dat + c@ ( x y pixel )
+      dup $40 and if \ fg
+        >r 2dup r@ _fg! r> _drawpixel
+        else >r 2dup _fg? if 2drop rdrop else r> _drawpixel then then
     endof
     drop endcase ;
 
 : screen_init
+  _fgmask FGMASKSZ 0 fill
   $2 ['] screendei ['] screendeo uxn_set_dev
   $112 vesamode! ;
 
diff --git a/fs/tests/manual/uxn/rect.tal b/fs/tests/manual/uxn/rect.tal
@@ -4,20 +4,34 @@
 %WIDTH { #42 }
 %HEIGHT { #54 }
 
+|0000 ( zero-page )
+
+@maxx $1
+@maxy $1
+@pixel $1
+
 |0100 ( -> )
 	( theme ) 
 	#0f0f .System/r DEO2 
 	#0ff0 .System/g DEO2 
 	#00ff .System/b DEO2
 
-    #00 ( y )
+    #00 #00 #42 ;draw-rect JSR2
+    WIDTH #01 SFT HEIGHT #01 SFT #01 ;draw-rect JSR2
+    BRK
+
+@draw-rect ( x y pixel -- )
+    
+    .pixel STZ
+    DUP HEIGHT ADD .maxy STZ ( xbase y )
+    OVR WIDTH ADD .maxx STZ ( xbase y )
     &loopy
         #00 OVR .Screen/y DEO2 INC
-        #00 ( y x )
+        OVR ( xbase y x )
         &loopx
             #00 OVR .Screen/x DEO2 INC
-            #41 .Screen/pixel DEO
-            DUP WIDTH LTH ,&loopx JCN
-        POP DUP HEIGHT LTH ,&loopy JCN
-    POP
-    BRK
+            .pixel LDZ .Screen/pixel DEO
+            DUP .maxx LDZ LTH ,&loopx JCN ( xbase y x )
+        POP DUP .maxy LDZ LTH ,&loopy JCN ( xbase y )
+    POP2
+JMP2r