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Fun with Texture Alphas and Prim Interiors

Void Singer
Int vSelf = Sing(void);
Join date: 24 Sep 2005
Posts: 6,973
09-29-2007 02:00
A few tricks I learned, didn't see them collected anywhere dealing with alpha sorting (texture transparency layers) and Prim Interiors (hollow and holes... thougt I'd make a list of them

A) is the 2 prim realistic table:
From: someone

the idea is to create a coffee table with realistic legs that can be seen from all sides (the back legs are still visible when looking from the side)

first create a texture, showing the table legs from the side one on each (r/l) edge, make the space between transparent in the alpha layer.

in SL rez 2 cubes, the first at size <0.95, 0.95, 0.5 > the second as size <1.0, 1.0, 0.5> and make this one hollow 95%

on the first (smaller)prim, select the side textures and set them to your table leg texture, on the second(hollow)prim select it inside (hole) texture, and replace it with your table leg texture, and change the horizontal repeats to 4.2 (the extra .2 to acount for the hidden edge), and change the horizontal offset to 0.6 (play with this if you're using other shapes

on the outside of the second(hollow) prim you can either make it 100% transparent, or create a texture that is the table edge, with all below it transparent on the alpha layer to give it a nice edge

on the top of both prims place a texture for your table top, and on the first (smaller) prim change the repeats for both Hrz. and Vert. to .95

center the hollow prim on the smaller prim (copy and paste the coordinates from one to the other) then link the prims

now you have a table, with a natural overhang, and four natural looking legs (w/o gaps at the edges) in 2 prims. playing with taper can give you angled legs as well. this works on any shape with a hollow, and can make really interesting filligree style spheres,


B) eyeball and "Aura";(cell shading) effects:
From: someone

ever see an object that seemed to have a aura(cell shading) or outline around it, or an eyball that always stared at the viewer? this is how it's done
Eyeball example:
create 2 spheres, sizes <0.3, 0.3, 0.3> and <0.2, 0.2, 0.2>.
set both to hollow 95% and path cut to 50% begin

select the outside texture for both, set the alpha to 100%
select the inside of the larger sphere, and set the color to white, texture blank
select the inside texture for the smaller sphere, set texture to blank, color to green(I like green eyes)

make a third sphere, size <0.1, 0.1, 0.1>, set outside texture color to black
set the path cut begin for both originals back to 0 and link all three
center one on the other (copy/paste coordinates from one to the others)

this will create an eyeball that always stares at the viewer, no matter how you move, or who views it. this trick works to give a aura(cell shading) to any prim shape with a hollow setting that is continuous (spheres, torii, tubes, rings) and looks great if you set the transparency down on the larger prim a little


C: "Aura";(cell shading) for Sculpted objects:
From: someone

create two scupties, one larger than the other
for the larger sculpty flip the scupt-map image top to bottom (this must be done outside SL, texture it with a single color (say black)

the smaller sculpty gets the original scuptmap, and whatever texture you wanted to use

link together, then center them over each other as above

this can create nice cartoon style outlines on sculpted objects, or with a little transparency on the larger prim, nice colored auras
Chosen Few
Alpha Channel Slave
Join date: 16 Jan 2004
Posts: 7,496
09-29-2007 14:14
Good tips. Just so you know, the "halo effect" you're talking about is usually referred to as "cell shading". You might want to edit your post to use that term.

Usually when people talk about "halos" here, it means something entirely different. A "halo" is a common undesirable texturing artifact resulting from improper alpha channel creation.

I'd suggest being careful not to risk having people confuse the two. Cell shading is a cool effect, done on purpose; haloing is an unwanted effect, created accidentally.
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Void Singer
Int vSelf = Sing(void);
Join date: 24 Sep 2005
Posts: 6,973
09-30-2007 01:26
good point, I was kinda afraid those that are newer might not get all the jargon (ok and I didn't know the proper term)... I was also told a video tutorial would've helped... must reinstall fraps or something, or maybe at least do screen shots... thx for the heads up