llGetAlpha

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/LSL

GetAlpha

llGetAlpha

Summary

Function: float llGetAlpha( integer face );

0.0	Forced Delay
10.0	Energy

Returns a float that is the Blinn-Phong alpha of face.

• integer

face

–

face number or ALL_SIDES

If face is ALL_SIDES then the function returns the sum of alpha of all the faces on the prim, range [0, sides]^[1]. Otherwise the return is in the range [0, 1], with 0.0 being fully transparent and 1.0 being fully solid.

Caveats

• If face indicates a face that does not exist the return is 1.0

Examples

//Tells the owner the alpha on all sides
default
{
    state_entry()
    {
        integer i = 0;
        integer max = llGetNumberOfSides();
        while(i < max)
        {
            llSay(0,"Face "+(string)i+" alpha is " + (string)llGetAlpha(i));
            ++i;
        }
    }
}

Useful Snippets

float AveragePrimAlpha()
{//Since this is so simple you may just want to inline it instead of including the function.
    return (llGetAlpha(ALL_SIDES) / llGetNumberOfSides());
}

//if face 0 is "transparent" then make the prim "visible"
if (llGetAlpha(0))  ;
else llSetAlpha(1.0, ALL_SIDES);

See Also

Functions

•	llSetAlpha	–	Sets the prim's alpha
•	llGetColor	–	Gets the prim's color
•	llSetColor	–	Sets the prim's color
•	llSetLinkColor	–	Sets link's color
•	llSetLinkAlpha	–	Sets link's alpha
•	llGetNumberOfSides	–	Gets the number of faces on the prim

Articles

•

Translucent Color

Deep Notes

Rounding

Alpha is stored in a single 8-bit byte, meaning there are 256 values that are possible. Consequently the values returned by this function are all multiples of 1/255. When the alpha value is initially stored the float value is rounded to the nearest multiple, turning 0.5 into 128/255 for example.

Footnotes

1. ^ The ranges in this article are written in Interval Notation.

Signature
function float llGetAlpha( integer face );