;;; -*- Mode:Lisp; Readtable:T; Package:USER; Base:10; Patch-File:T -*-
;;; Patch file for MEDIUM-RESOLUTION-COLOR version 17.1
;;; Reason:
;;;  Change makes color-draw-line sort args properly so it can draw left-to-right.  It was only sorting the "x"s!  AND changed to COND.
;;; Written 4-Feb-85 17:10:28 by PECANN,
;;; while running on Waiting for Godot from band 2
;;; with Experimental System 102.50, Experimental Local-File 55.3, Experimental FILE-Server 13.1, Experimental Unix-Interface 5.1, Experimental MagTape 40.6, Experimental ZMail 57.0, Experimental MEDIUM-RESOLUTION-COLOR 17.0, Experimental MICRO-COMPILATION-TOOLS 1.0, NIL Tiger 8.0, Experimental iris 3.0, microcode 729, IRIS.



; From file COLOR.LISP#> QL.VIDEO-DEVICE; LAM3: (10)
#10R COLOR#:
(COMPILER-LET ((*PACKAGE* (PKG-FIND-PACKAGE "COLOR")))
  (COMPILER#:PATCH-SOURCE-FILE "SYS: VIDEO-DEVICE; COLOR  "

(DEFUN COLOR-DRAW-LINE (X1 Y1 X2 Y2
			&OPTIONAL (COLOR 17) (ALU TV:ALU-SETA) (SCREEN COLOR-SCREEN))
  "Draw a line from X1, Y1 to X2, Y2 in color COLOR."
    (COND ((> X1 X2) (SWAPF X1 X2) (SWAPF Y1 Y2)))
    (TV:PREPARE-SHEET (SCREEN)
      (LET ((DX (- X2 X1))
	    (DY (- Y2 Y1))
	    (PIXEL-ARRAY (TV:SHEET-SCREEN-ARRAY COLOR-SCREEN)))
	(LET ((DIR-Y (IF (MINUSP DY) -1 1))
	      (DY (ABS DY)))
	  (COND ((ZEROP DY) (RECTANGLE X1 Y1 (- X2 X1) 1 COLOR ALU))
		((ZEROP DX) (RECTANGLE X1 (MIN Y1 Y2) 1 (- (MAX Y1 Y2) (MIN Y1 Y2))
				       COLOR ALU))
		((> DX DY)			;X IS LARGER STEP
		 (DO ((X1 X1 (1+ X1))
		      (REM (TRUNCATE DY 2) (+ REM DY)))
		     ((> X1 X2))
		   (IF ( REM DX) (SETQ Y1 (+ Y1 DIR-Y) REM (- REM DX)))
		   (AS-2-REVERSE (BOOLE ALU COLOR (AR-2-REVERSE PIXEL-ARRAY X1 Y1))
				 PIXEL-ARRAY X1 Y1)))
		(T				;Y IS LARGER STEP
		 (DO ((I 0 (1+ I))
		      (Y Y1 (+ Y DIR-Y))
		      (REM (TRUNCATE DX 2) (+ REM DX)))
		     ((> I DY))
		   (IF ( REM DY) (SETQ X1 (1+ X1) REM (- REM DY)))
		   (AS-2-REVERSE (BOOLE ALU COLOR (AR-2-REVERSE PIXEL-ARRAY X1 Y))
				 PIXEL-ARRAY X1 Y))))))))

))