'===========================================================================
' Subject: MATRIX SCREEN PAINT DEMO          Date: 01-28-96 (11:23)       
' Author:  David A. Wicker                   Code: QB, QBasic, PDS        
' Origin:  david@fastlane.net              Packet: GRAPHICS.ABC
'===========================================================================
DEFINT A-Z
' * Matrix Paint (C) 1996+ David A. Wicker

CLS
LOCATE 12, 1
PRINT "MATRIX SCREEN PAINT DEMO"
PRINT "Use arrow keys (with NUM-LOCK lit), and [CR] to paint region"
PRINT "[ESC] to exit demo."
PRINT
INPUT "", A$

SCREEN 1
DEF FNR (A) = INT(RND * A)
RANDOMIZE TIMER

FOR I = 1 TO 50
  LINE (FNR(320), FNR(200))-(FNR(320), FNR(200))
NEXT

Again:
  DO
	C = POINT(H, V)
	PSET (H, V), 1
	DO
	  K$ = INKEY$
	LOOP UNTIL K$ > ""
	IF K$ = CHR$(27) THEN
	  SCREEN 0
	  WIDTH 80
	  LOCATE 12, 1
	  PRINT "Matrix Screen Painter (C) 1996+ David A. Wicker"
	  END
	END IF
	PSET (H, V), C
	IF K$ = "8" THEN V = V - 5
	IF K$ = "2" THEN V = V + 5
	IF K$ = "4" THEN H = H - 5
	IF K$ = "6" THEN H = H + 5
  LOOP UNTIL K$ = CHR$(13)
  PSET (H, V), 1

  DO
	OK = 1
	FOR I = 0 TO 199
	  FOR J = 0 TO 319
		IF POINT(J, I) = 1 THEN
		  IF POINT(J + 1, I) = 0 THEN PSET (J + 1, I), 1: OK = 0
		  IF POINT(J, I + 1) = 0 THEN PSET (J, I + 1), 1: OK = 0
		END IF
		IF POINT(319 - J, 199 - I) = 1 THEN
		  IF POINT(318 - J, 199 - I) = 0 THEN PSET (318 - J, 199 - I), 1: OK = 0
		  IF POINT(319 - J, 198 - I) = 0 THEN PSET (319 - J, 198 - I), 1: OK = 0
		END IF
	  NEXT
	NEXT
  LOOP UNTIL OK = 1
  SOUND 800, .1

GOTO Again