From Second Life Wiki
Revision as of 13:26, 1 December 2023 by Jenna Huntsman (talk | contribs) (Add Blinn-Phong terminology to page following PBR release.)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to navigation Jump to search


Function: float llGetAlpha( integer face );

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.


  • If face indicates a face that does not exist the return is 1.0
All Issues ~ Search JIRA for related Bugs


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


•  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


•  Translucent Color

Deep Notes


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.

Search JIRA for related Issues


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


function float llGetAlpha( integer face );