A Hoverlogo And Other Sprites

Particles are two-dimensional images situated in 3-D space. They (except still-rare "ribbon" particles) have the special property of always facing the camera: they're "sprites" is the parlance of computer graphics. This is fine for many purposes, but in other situations can challenge immersion: there's no real world analogue of a surface that's always facing you regardless of how your view moves around it.

Well, there's the optical illusion of eyes in paintings such as the Mona Lisa that appear to follow as the viewer moves around the room, but particle sprites really do face the cam.

That's similar to hovertext which, too, is always drawn facing the cam; one big difference is that hovertext doesn't scale with distance from the emitter whereas particles do.

In SL, things that aren't realistic may break immersion -- or they may appear magical. Here we have what I prefer to see as magical: a "hoverlogo" that always shows the circular logo image head-on, regardless of whence it's viewed:

, PSYS_SRC_TEXTURE, "422ed2fa-482d-b9fd-1bd7-eef1611a1dbf"
, PSYS_PART_START_SCALE, <0.5, 0.5 , 0.0>
llSetText( "Visit the\nBay City Post", <1.0, 1.0, 1.0>, 1.0);

touch_start(integer total_number)
llLoadURL(llDetectedKey(0), "Visit the Bay City Post online",

This example is intended to go inside a fully transparent 0.5 m sphere so it can be activated by touch. Of course for another logo you'll want to change the texture UUID and hovertext as well as the prompting text and URL that's loaded when touched. If no touch-response is desired, the particle system will continue to show the logo after the script is removed, saving a tiny bit of simulator resources.

I've also used this approach to create an analogue "hoverclock" that shows the time from all sides, perched on top of teleport domes on major Virtual Railway Consortium sites around the SLRR. (The reader is invited to ponder the mystery of how the hands move around the face of those hoverclocks.)
Reporter Qie Niangao

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