HSV to RGB conversion

RGB led light are becoming very popular, but controlling them by Red, Green and Blue groups is not very intuitive. This logic allows the use of the HSV (Hue, Saturation and Value) colour model to control RGB lights. Hue sets the actual colour, Saturation is the amout of white (i.e. colour intensity), and Value is the overall light level.

On a touch screen you can use 3 sliders to set the SystemIO values. On a Wiser you're stuck with the SystemIO widget, or with minor mods to the HSV modeul you could use 3 phantom groups and a Dimmer widget. In this case you would need to scale the Hue from 0-255 up to 0-359.

Code:

{SystemIO's}
Hue: Integer, Min:0, Max:359
Saturation: Integer, Min:0, Max:255
Value: Integer, Min:0, Max:255

{Global Variables}
hue, saturation, value: integer;
red, green, blue: integer;

{Procedure : hsv_to_rgb}
//
// Convert HSV colour space to RGB and set groups
// H = hue. 0-359 degrees
// S = Saturation. 0-255
// V = Value. 0-255
// R, G, B return values 0-255
//
procedure hsv_to_rgb(h,s,v: integer; var r: integer; var g: integer; var b: integer);
var
  hQuadrant, hOffset, vs, p, q, t: integer;
 begin
  if s = 0 then // monochrome
  begin
    r := v;
    g := v;
    b := v;
  end
  else
  begin
    hQuadrant := h div 60;     // Hue quadrant 0 - 5 (60deg)
    hOffset := h mod 60;     // Hue position in quadrant
    vs := v * s;
    p := v - (vs div 255);
    q := v - (vs div 255 * hOffset) div 60;
    t := v - (vs div 255 * (60 - hOffset)) div 60;
    case hQuadrant of
      0:  begin r := v; g := t; b := p; end;
      1:  begin r := q; g := v; b := p; end;
      2:  begin r := p; g := v; b := t; end;
      3:  begin r := p; g := q; b := v; end;
      4:  begin r := t; g := p; b := v; end;
      5:  begin r := v; g := p; b := q; end;
    end;
  end;
end;

{Modules: HSV}
//
 // Look for HSV slider changes and set RGb outputs
 // Uses 3 System IO's: Hue: 0-359, Saturation: 0-255, Value: 0-255
 //
  hue := GetIntSystemIO("Hue");
  saturation := GetIntSystemIO("Saturation");
  value := GetIntSystemIO("Value");
  if hasChanged(hue) or hasChanged(Saturation) or hasChanged(Value) then
  begin
    hsv_to_rgb(hue, saturation, value, red, green, blue);
    SetCBusLevel("Local", "Theatre Leds", "Led 0/RGB 0R", red, "0s");
    SetCBusLevel("Local", "Theatre Leds", "Led 1/RGB 0G", green, "0s");
    SetCBusLevel("Local", "Theatre Leds", "Led 2/RGB 0B", blue, "0s");
  end;

 

I am posting this as a reply to a private message I received which I could not reply to and the e-mail address supplied bounced back

The question was regarding changing the main HSV module to control different group addresses of a DMX system. The revised code is as follows:

Code:

{Modules: HSV}
//
// Look for HSV slider changes and set RGb outputs // Uses 3 System IO's: Hue: 0-359, Saturation: 0-255, Value: 0-255
//
hue := GetIntSystemIO("Hue");
saturation := GetIntSystemIO("Saturation");
value := GetIntSystemIO("Value");
if hasChanged(hue) or hasChanged(Saturation) or hasChanged(Value) then
begin
       hsv_to_rgb(hue, saturation, value, red, green, blue);
         SetLightingLevel("DMX Red", red, "0s");
         SetLightingLevel("DMX Green", green, "0s");
         SetLightingLevel("DMX Blue", blue, "0s");
end;

 

Any Idea How you would go about running this on a SHAC?