VDU19 Tutorial 013

Any Colour! - VDU19 -Tutorial 013

VDU 19,logical,16,red,green,blue is a command which enables you to get any colour you like on the screen as this and the next program will show you :

VDU19 Demo

      MODE8:OFF
      message$ = "Click mouse to pause"
      caption$ = "Control"
      SYS "MessageBox", @hwnd%, message$, caption$, 0
      REPEAT
        red=RND(255)
        green=RND(255)
        blue=RND(255)
        VDU 19,1,16,red,green,blue
        GCOL0,1
        CIRCLE FILL RND(1280),RND(1024),(10+RND(100))
        delay=INKEY(5)
        Stop=INKEY(-10)
        IF Stop THEN
          message$ = "Press any key for more circles"
          caption$ = "To Restart"
          SYS "MessageBox", @hwnd%, message$, caption$, 0
          G=GET
        ENDIF
      UNTIL FALSE

Annotated Listing

      MODE8:OFF ***Mode 8 has 16 "logical colours"***
------------------------------------------------------------------------------------------------------------------------------
      message$ = "Click mouse to pause" *** See previous tutorial for another message box.....
      caption$ = "Control"
      SYS "MessageBox", @hwnd%, message$, caption$, 0
-------------------------------------------------------------------------------------------------------------------------------
      REPEAT
        red=RND(255) ****values of red, green, blue go from 0 to 255***
        green=RND(255)
        blue=RND(255)
--------------------------------------------------------------------------------------------------------------------------------        VDU 19,1,16,red,green,blue *****

The "1" specifies the first out of 16 possible "logical colours" available in MODE8 is to be redefined from its default colour (in this case red)
"16" specifies that the following three parameters (numbers), will indicate the mixture of red, green and blue to be used in making the redefined colour.

-------------------------------------------------------------------------------------------------------------------------------
      GCOL0,1 ***** GCOL0 specifies "normal colours" which cover other colours in an uncomplicated way; the 1 indicates that graphics colour 1 (which we have just redefined is to be used.
------------------------------------------------------------------------------------------------------------------------------
        CIRCLE FILL RND(1280),RND(1024),(10+RND(100)) ****coloured discs which over-print each other
        delay=INKEY(5)**** If you alter this to read "delay=INKEY(0)" you will see why it is here
--------------------------------------------------------------------------------------------------------------------------------
        Stop=INKEY(-10) *****INKEY(-10) is TRUE if the left mouse button is held down as this instruction is executed
        IF Stop THEN **** Halts program until you click the mouse (or touch a key)
          message$ = "Press any key for more circles"
          caption$ = "To Restart"
          SYS "MessageBox", @hwnd%, message$, caption$, 0
          G=GET ***** halts until a key is pressed, then allows more coloured discs to be printed
        ENDIF
      UNTIL FALSE **** loops back from here to produce another coloured disc

Colour Possibilities!

      MODE8:OFF
      message$ = "Keep Pressing any key to see next display"
      caption$ = "Control"
      SYS "MessageBox", @hwnd%, message$, caption$, 0
      REPEAT
        red=RND(255)
        green=RND(255)
        blue=RND(255)
        VDU 19,1,16,red,green,blue
        PRINTTAB(30,2)"red = ";red;SPC(2)
        PRINTTAB(30)"green : ";green;SPC(2)
        PRINTTAB(30)"blue = ";blue;SPC(2)
        PRINTTAB(30,24)"VDU19,1,16,";red;",";green;",";blue;SPC(8)
        GCOL0,1
        RECTANGLE FILL 80,400,1100,400
        G=GET
      UNTIL FALSE

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