Targas with alpha 1 bit, is there a way?

bugo

Is there a way to setup targa images with only 1 bit in alpha?

MoP

Not as far as I know... why?
If you're thinking of "1-bit alpha", that's just a term used to define off/on transparency.

bugo

Damn MOP, you are so fast! I need to setup alpha as 1-bit in Infernal Engine to cast shadows as the set only cast shadows from meshes that has 1bit alpha only.

bugo

I might need to find this inside the engine, I'll let you know if I find any success.

Eric Chadwick

Usually called "alpha test". Also usually you get the smoothest results if you have smooth alpha, and let the shader do the cutoff.

bugo

true, but still lightmap is not working inside the engine, but its ok, thanks a lot guys.

Farfarer

Most engines I've seen are smart enough to work out that a texture with only black and white in the alpha channel is to be interpreted as a 1-bit alpha.

But as Eric says, there will tend to be a setting somewhere to allow you to specify it as an alpha test.

Which engine is it you're using?

Slum

on the subject of alpha testing, here's a great article by valve on generating distance fields for alpha data. yields much nicer looking results than traditional methods, and is super easy to implement

www.valvesoftware.com/publications/2007/SIGGRAPH2007_AlphaTestedMagnification.pdf

MoP

Talon wrote: »

Most engines I've seen are smart enough to work out that a texture with only black and white in the alpha channel is to be interpreted as a 1-bit alpha.

Really? Most engines I've seen, you have to tell it to use the alpha channel as a 1-bit alpha, unless the stuff you've used does it automatically (ie. always assume alpha-channel in a diffuse texture is to be used as alphatest) which makes some sense, but it's not really the engine working out that it's a 1-bit alpha based on the value of the pixels in the alpha channel.

I doubt there are many engines which detect if any mid-grey pixels are in the alpha channel and use that to determine what type of transparency to use...

renderhjs

Slum: can you repost the link - seems it got crunched by the system. Maybe quote it or disable auto generate links.
I'd really like to read that

pior

http://www.valvesoftware.com/publications/2007/SIGGRAPH2007_AlphaTestedMagnification.pdf

renderhjs

thx

bugo

I'm using Infernal Engine, and yes, there is a alpha testing thing that you can set your alpha to only render on a "x"value. But even like that its not working as it supposed to be. But thanks guys.

John Warner

... lightmap not working? you're using lightmaps as well?

I know that unity can't have an object use lightmaps and transparency at the same time (as far as i know)

that might be related to the issue you're havin... ??

bugo

yes, thing is, guys from Terminal Reality told me that I can use alpha 1bit only so it gets baked.