( isometric cube )

%+  { ADD }  %-  { SUB }  %*  { MUL }  %/  { DIV }
%<  { LTH }  %>  { GTH }  %=  { EQU }  %!  { NEQ }
%++ { ADD2 } %-- { SUB2 } %** { MUL2 } %// { DIV2 }
%<< { LTH2 } %>> { GTH2 } %== { EQU2 } %!! { NEQ2 }

%2*  { #10 SFT } %2/  { #01 SFT } %2**  { #10 SFT2 } %2//  { #01 SFT2 }
%4*  { #20 SFT } %4/  { #02 SFT } %4**  { #20 SFT2 } %4//  { #02 SFT2 }
%8*  { #30 SFT } %8/  { #03 SFT } %8**  { #30 SFT2 } %8//  { #03 SFT2 }
%10* { #40 SFT } %10/ { #04 SFT } %10** { #40 SFT2 } %10// { #04 SFT2 }
%20* { #50 SFT } %20/ { #05 SFT } %20** { #50 SFT2 } %20// { #05 SFT2 }

%ABS2 { DUP2 #0f SFT2 EQU #05 JCN #0000 SWP2 SUB2 }
%LTS2  { #8000 ADD2 SWP2 #8000 ADD2 GTH2 }
%GTS2  { #8000 ADD2 SWP2 #8000 ADD2 LTH2 }

%DEBUG      { ;print-hex/byte JSR2 #0a18 DEO }
%DEBUG2     { ;print-hex JSR2 #0a18 DEO }
%RTN        { JMP2r }

( devices )

|00 @System     &vector $2 &wst      $1 &rst    $1 &eaddr  $2 &ecode  $1 &pad     $1 &r       $2 &g      $2 &b     $2 &debug  $1 &halt $1
|20 @Screen     &vector $2 &width    $2 &height $2 &auto   $1 &pad    $1 &x       $2 &y       $2 &addr   $2 &pixel $1 &sprite $1

( variables )

|0000

@cube
	&v0 $8
	&v4 $8
@timer $1
@color $1
@line 
	&x0 $2 &y0 $2
	&x $2 &y $2 
	&sx $2 &sy $2 
	&dx $2 &dy $2 
	&e1 $2 &e2 $2
@center
	&x $2 &y $2

( program )

|0100 ( -> )

	( theme )
	#0fe5 .System/r DEO2
	#0fc5 .System/g DEO2
	#0f25 .System/b DEO2

	.Screen/width DEI2 2// #0040 -- .center/x STZ2
	.Screen/height DEI2 2// #0040 -- .center/y STZ2

	;on-frame .Screen/vector DEO2

@on-frame ( -> )

	#00 ;draw-cube JSR2
	.timer LDZk INC SWP STZ
	#05 ;draw-cube JSR2

BRK

@draw-cube ( frame color -- )

	.color STZ
	( create box )
	#0800
	&loop
		STHk
		#00 .timer LDZ [ #00 STHkr INC #07 AND #60 SFT ++ ] #00ff AND2 ;table ++ LDA 2/
		#00 .timer LDZ [ #00 STHkr #60 SFT ++ ] #00ff AND2 ;table ++ LDA 4/ [ #00 STHkr #62 SFT2 ++ ]
		.cube/v0 STHr 2* + STZ2
		INC GTHk ,&loop JCN
	POP2
	( vertices )
	#0800
	&ver-loop
		DUP 2* .cube + LDZ2 ;draw-vertex JSR2
		INC GTHk ,&ver-loop JCN
	POP2
	( lines )
	#0400
	&line-loop
		STHk
		.cube/v0 STHkr 2* + .cube/v0 STHkr INC #03 AND 2* + ;draw-line JSR2
		.cube/v0 STHkr 2* + .cube/v4 STHkr 2* + ;draw-line JSR2
		.cube/v4 STHkr 2* + .cube/v4 STHr INC #03 AND 2* + ;draw-line JSR2
		INC GTHk ,&line-loop JCN
	POP2

RTN

@draw-line ( a b -- )

	STH STH
	#00 STHkr LDZ .center/x LDZ2 ++ #00 STHr INC LDZ .center/y LDZ2 ++
	#00 STHkr LDZ .center/x LDZ2 ++ #00 STHr INC LDZ .center/y LDZ2 ++
		.color LDZ ;line-slow JSR2

RTN

@draw-vertex ( x y -- )

	#00 SWP #0004 -- .center/y LDZ2 ++ .Screen/y DEO2
	#00 SWP #0003 -- .center/x LDZ2 ++ .Screen/x DEO2
	;&icn .Screen/addr DEO2
	.color LDZ 2* .Screen/sprite DEO

RTN
	&icn 0000 387c 7c7c 3800

@line-slow ( x1 y1 x2 y2 color -- )
	
	( load ) .color STZ #0001 SUB2 .line/y0 STZ2 #0001 SUB2 .line/x0 STZ2 .line/y STZ2 .line/x STZ2
	.line/x0 LDZ2 .line/x LDZ2 SUB2 ABS2 .line/dx STZ2
	.line/y0 LDZ2 .line/y LDZ2 SUB2 ABS2 #0000 SWP2 SUB2 .line/dy STZ2
	#ffff #00 .line/x LDZ2 .line/x0 LDZ2 LTS2 2** ADD2 .line/sx STZ2
	#ffff #00 .line/y LDZ2 .line/y0 LDZ2 LTS2 2** ADD2 .line/sy STZ2
	.line/dx LDZ2 .line/dy LDZ2 ADD2 .line/e1 STZ2
	&loop
		.line/x LDZ2 .Screen/x DEO2 .line/y LDZ2 .Screen/y DEO2 .color LDZ .Screen/pixel DEO
		.line/x LDZ2 .line/x0 LDZ2 EQU2 .line/y LDZ2 .line/y0 LDZ2 EQU2 #0101 EQU2 ,&end JCN
		.line/e1 LDZ2 2** .line/e2 STZ2
		.line/e2 LDZ2 .line/dy LDZ2 LTS2 ,&skipy JCN
			.line/e1 LDZ2 .line/dy LDZ2 ADD2 .line/e1 STZ2
			.line/x LDZ2 .line/sx LDZ2 ADD2 .line/x STZ2
		&skipy
		.line/e2 LDZ2 .line/dx LDZ2 GTS2 ,&skipx JCN
			.line/e1 LDZ2 .line/dx LDZ2 ADD2 .line/e1 STZ2
			.line/y LDZ2 .line/sy LDZ2 ADD2 .line/y STZ2
		&skipx
		;&loop JMP2

	&end

RTN

@table ( 256 xy )
	f7f8 f9fa fbfc fcfd fefe ffff ffff ffff
	ffff ffff fffe fefd fcfc fbfa f9f8 f7f6
	f5f3 f2f0 efed ecea e8e6 e4e2 e0de dcda
	d8d5 d3d1 cecc c9c7 c4c1 bfbc b9b6 b3b0
	aeab a8a5 a29f 9c98 9592 8f8c 8986 8380
	7c79 7673 706d 6a67 6360 5d5a 5754 514f
	4c49 4643 403e 3b38 3633 312e 2c2a 2725
	2321 1f1d 1b19 1715 1312 100f 0d0c 0a09
	0807 0605 0403 0302 0101 0000 0000 0000
	0000 0000 0001 0102 0303 0405 0607 0809
	0a0c 0d0f 1012 1315 1719 1b1d 1f21 2325
	272a 2c2e 3133 3638 3b3e 4043 4649 4c4f
	5154 575a 5d60 6367 6a6d 7073 7679 7c7f
	8386 898c 8f92 9598 9c9f a2a5 a8ab aeb0
	b3b6 b9bc bfc1 c4c7 c9cc ced1 d3d5 d8da
	dcde e0e2 e4e6 e8ea eced eff0 f2f3 f5f6