Difference between revisions of "LlGetAlpha"

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|p1_type=integer|p1_name=face
|p1_type=integer|p1_name=face
|func_footnote=
|func_footnote=
Otherwise the return is in the range {{Interval|gte=0|lte=1|center=return}}.
Otherwise the return is in the range {{Interval|gte=0|lte=1|center=return}}, with 0.0 being fully transparent and 1.0 being fully solid.
|func_desc
|func_desc
|return_text=that is the alpha of {{LSLP|face}}.
|return_text=that is the alpha of {{LSLP|face}}.
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     return (llGetAlpha(ALL_SIDES) / llGetNumberOfSides());
     return (llGetAlpha(ALL_SIDES) / llGetNumberOfSides());
}</source>
}</source>
<source lang="lsl2">//if face 0 is "transparent" then make the prim "visible"
if (llGetAlpha(0))  ;
else llSetAlpha(1.0, ALL_SIDES);</source>
|also_functions=
|also_functions=
{{LSL DefineRow||[[llSetAlpha]]|Sets the prim's alpha}}
{{LSL DefineRow||[[llSetAlpha]]|Sets the prim's alpha}}

Revision as of 11:53, 8 June 2018

Summary

Function: float llGetAlpha( integer face );

Returns a float that is the 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
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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.

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Footnotes

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

Signature

function float llGetAlpha( integer face );