OsSetPenColor

string osSetPenColor(string drawList, vector color)
string osSetPenColor(string drawList, vector color, float alpha)

// Example of osSetPenColor
 
string hexDigits = "0123456789abcdef";
list colorNames = [
    "AliceBlue", "AntiqueWhite", "Aqua", "Aquamarine", "Azure", "Beige", "Bisque",
    "Black", "BlanchedAlmond", "Blue", "BlueViolet", "Brown", "BurlyWood",
    "CadetBlue", "Chartreuse", "Chocolate", "Coral", "CornflowerBlue", "Cornsilk",
    "Crimson", "Cyan", "DarkBlue", "DarkCyan", "DarkGoldenrod", "DarkGrey",
    "DarkGreen", "DarkKhaki", "DarkMagenta", "DarkOliveGreen", "DarkOrange",
    "DarkOrchid", "DarkRed", "DarkSalmon", "DarkSeaGreen", "DarkSlateBlue",
    "DarkSlateGrey", "DarkTurquoise", "DarkViolet", "DeepPink", "DeepSkyBlue",
    "DimGrey", "DodgerBlue", "FireBrick", "FloralWhite", "ForestGreen", "Fuchsia",
    "Gainsboro", "GhostWhite", "Gold", "Goldenrod", "Grey", "Green", "GreenYellow",
    "Honeydew", "HotPink", "IndianRed", "Indigo", "Ivory", "Khaki", "Lavender",
    "LavenderBlush", "LawnGreen", "LemonChiffon", "LightBlue", "LightCoral",
    "LightCyan", "LightGoldenrodYellow", "LightGreen", "LightGrey", "LightPink",
    "LightSalmon", "LightSeaGreen", "LightSkyBlue", "LightSlateGrey",
    "LightSteelBlue", "LightYellow", "Lime", "LimeGreen", "Linen", "Magenta",
    "Maroon", "MediumAquamarine", "MediumBlue", "MediumOrchid", "MediumPurple",
    "MediumSeaGreen", "MediumSlateBlue", "MediumSpringGreen", "MediumTurquoise",
    "MediumVioletRed", "MidnightBlue", "MintCream", "MistyRose", "Moccasin",
    "NavajoWhite", "Navy", "OldLace", "Olive", "OliveDrab", "Orange", "OrangeRed",
    "Orchid", "PaleGoldenrod", "PaleGreen", "PaleTurquoise", "PaleVioletRed",
    "PapayaWhip", "PeachPuff", "Peru", "Pink", "Plum", "PowderBlue", "Purple",
    "Red", "RosyBrown", "RoyalBlue", "SaddleBrown", "Salmon", "SandyBrown",
    "SeaGreen", "Seashell", "Sienna", "Silver", "SkyBlue", "SlateBlue", "SlateGrey",
    "Snow", "SpringGreen", "SteelBlue", "Tan", "Teal", "Thistle", "Tomato",
    "Turquoise", "Violet", "Wheat", "White", "WhiteSmoke", "Yellow", "YellowGreen"
];
 
default
{
    state_entry()
    {
        // Storage for our drawing commands
        string CommandList = "";
        integer i;
        // Set the pen width to 1 pixel
        CommandList = osSetPenSize(CommandList, 1);
 
        // draw each named color as a single horizontal line
        for (i = 0; i < 140; ++i)
        {
            // Set the pen to the next color name in our list
            CommandList = osSetPenColor(CommandList, llList2String( colorNames, i));
            // Now draw a line in that color
            CommandList = osDrawLine(CommandList, 0, i, 255, i);
        }
 
        // Now let's fill up the remainder with lines of random colors, leaving a gap of 20 lines.
        for (i = 161; i < 256; ++i)
        {
            // give it an opaque alpha
            string thisColor = "ff";
            integer j;
 
            // then choose six random hex digits for the color
            for (j = 0; j < 6; ++j)
            {
                integer k = (integer)llFrand(16.0);
                thisColor += llGetSubString(hexDigits, k, k);
            }
            CommandList = osSetPenColor(CommandList, thisColor);
            CommandList = osDrawLine(CommandList, 0, i, 255, i);
        }
        // Now generate the texture and apply it to the prim
        osSetDynamicTextureData("", "vector", CommandList, "width:256,height:256", 0);
    }
}

// Generating a calibrated color checker
 
integer SIZE    = 512;
integer NROWS   = 4;
integer NCOLS   = 6;
integer MARGIN  = 6;
 
// Color definitions in xyY space
// https://home.cis.rit.edu/~cnspci/references/mccamy1976.pdf
 
list xyYColors = [
    <0.400, 0.350, 10.1>,
    <0.377, 0.345, 35.8>,
    <0.247, 0.251, 19.3>,
    <0.337, 0.422, 13.3>,
    <0.265, 0.240, 24.3>,
    <0.261, 0.343, 43.1>,
    <0.506, 0.407, 30.1>,
    <0.211, 0.175, 12.0>,
    <0.453, 0.306, 19.8>,
    <0.285, 0.202, 6.60>,
    <0.380, 0.489, 44.3>,
    <0.473, 0.438, 43.1>,
    <0.187, 0.129, 06.1>,
    <0.305, 0.478, 23.4>,
    <0.539, 0.313, 12.0>,
    <0.448, 0.470, 59.1>,
    <0.364, 0.233, 19.8>,
    <0.196, 0.252, 19.8>,
    <0.310, 0.316, 90.0>,
    <0.310, 0.316, 59.1>,
    <0.310, 0.316, 36.2>,
    <0.310, 0.316, 19.8>,
    <0.310, 0.316, 09.0>,
    <0.310, 0.316, 03.1>
];
 
vector CIExyY_to_CIEXYZ (vector xyY)
{
    return 
    <
        xyY.x * xyY.z / xyY.y,
        xyY.z,
        (1.0 - xyY.x - xyY.y) * xyY.z / xyY.y
    >;
}
 
vector CIEXYZ_to_RGB709 (vector XYZ)
{
    return 
    <
         3.240479 * XYZ.x - 1.53715  * XYZ.y - 0.498535 * XYZ.z,
        -0.969256 * XYZ.x + 1.875991 * XYZ.y + 0.041556 * XYZ.z,
         0.055648 * XYZ.x - 0.204043 * XYZ.y + 1.057311 * XYZ.z
    >;
}
 
drawChart(integer side)
{
    string drawList = "";
    drawList = osSetPenColor         (drawList, "Black");
    drawList = osMovePen             (drawList, 0, 0);
    drawList = osDrawFilledRectangle (drawList, SIZE, SIZE);
 
    for (integer row=0; row<NROWS; row++)
        for (integer col=0; col<NCOLS; col++)
        {
            integer colorindex = row*NCOLS + col;
            vector xyYColor = llList2Vector (xyYColors,colorindex);
            vector XYZColor = CIExyY_to_CIEXYZ (xyYColor); // Convert to XYZ space
            vector RGB709   = CIEXYZ_to_RGB709 (XYZColor); // Convert to 'linear' RGB space
            RGB709 *= 0.01;                                // Normalize luminance to ~ 1
            vector sRGB     = llLinear2sRGB (RGB709);      // Apply sRGB gamma
 
            // Color space transformations may produce components outside [0..1]
            // osSetPenColor will take care to clamp the values to this range
 
            integer pos_y = (row * SIZE/NROWS) +MARGIN;
            integer pos_x = (col * SIZE/NCOLS) +MARGIN;
 
            integer siz_y = (SIZE/NROWS) - (2*MARGIN);
            integer siz_x = (SIZE/NCOLS) - (2*MARGIN);
 
            drawList = osSetPenColor         (drawList, sRGB);
            drawList = osMovePen             (drawList, pos_x, pos_y);
            drawList = osDrawFilledRectangle (drawList, siz_x, siz_y);
        }
 
    osSetDynamicTextureDataFace ("", "vector", drawList, 
                                   "width:"  +(string)SIZE
                                +", height:" +(string)SIZE,
                                0, side);
}
 
default
{
    touch_start (integer n)
    {
        drawChart(1);
    }
 
}