Difference between revisions of "LlGetAlpha"

From Second Life Wiki
Jump to navigation Jump to search
m
m
(14 intermediate revisions by 4 users not shown)
Line 1: Line 1:
{{LSL_Function/face|face|return=0.0|get=returns the sum of alpha of all the faces on the prim.}} {{LSL_Function/alpha|alpha}} {{LSL_Function
{{LSL_Function
|inject-2={{LSL_Function/face|face|return=1.0|get=returns the sum of alpha of all the faces on the prim, range {{Interval|gte=0|lte=[[llGetNumberOfSides|sides]]|lteh=sides|center=return}}{{Interval/Footnote}}.}}
{{LSL_Function/alpha|alpha}}
|func_id=50|func_sleep=0.0|func_energy=10.0
|func_id=50|func_sleep=0.0|func_energy=10.0
|func=llGetAlpha|return_type=float|p1_type=integer|p1_name=face
|func=llGetAlpha|return_type=float
|func_footnote=The return is in the [http://id.mind.net/~zona/mmts/miscellaneousMath/intervalNotation/intervalNotation.html range] [0, 1]
|p1_type=integer|p1_name=face
|func_footnote=
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 '''face'''.
|return_text=that is the alpha of {{LSLP|face}}.
|spec
|spec
|caveats
|caveats
|constants
|constants
|examples=
|examples=
<lsl>//Tells the owner the alpha on all sides
<source lang="lsl2">//Tells the owner the alpha on all sides
default
default
{
{
Line 22: Line 26:
         }
         }
     }
     }
}</lsl>
}</source>
|helpers=
|helpers=
<lsl>float AveragePrimAlpha()
<source lang="lsl2">float AveragePrimAlpha()
{//Since this is so simple you may just want to inline it instead of including the function.
{//Since this is so simple you may just want to inline it instead of including the function.
     return (llGetAlpha(ALL_SIDES) / llGetNumberOfSides());
     return (llGetAlpha(ALL_SIDES) / llGetNumberOfSides());
}</lsl>
}</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}}
Line 40: Line 47:
|notes
|notes
|permission
|permission
|negative_index
|deepnotes=
====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.
|cat1
|cat1
|cat2
|cat2

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
All Issues ~ Search JIRA for related Bugs

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.

Search JIRA for related Issues

Footnotes

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

Signature

function float llGetAlpha( integer face );