Can a Q2 model have an alpha?

[The Happy Friar]

IE like a piece of glass in a door, a modeled window, etc.

When I made my model with the same pink-ish color the main menu uses for alpha it's either black (software mode) or white (OGL mode).

[Whirlingdervish]

I don't think any type of moveable entity in q2 is able to have alpha/transparent parts, including models.

This is why you won't see a clear window on a moving platform/elevator or train in q2.

[The Happy Friar]

doesn't even have to be moving, but I'm betting then all md2's can be considered moving then if that's the case.

[themuffinman]

WAL and PCX images cannot have alpha channels.

You'll have to have TGA images to have alpha channels and these will have to be scripted into a modified renderer that can also support TGA's. I know Q2 Evolved supports scripts but I'm not sure about R1GL and EGL. :/
PNG's can also be used and with this type of image, alpha channels are not needed since a PNG image can be a floating, single-layer image, as opposed to a merged one where there is no transparency.

[Slayer :D]

I tried making a transparent .PNG texture once (NOT FOR CHEATING, JUST TESTING!!!). r1gl is created in such a way that it thows out alpha components to prevent wallhacks.

[The Happy Friar]

wal & pcx don't have an alpha channel, but the engine makes an alpha based on them. 

I did another quick test.  Any texture on a brush doesn't have the alpha color work.  It shows a black/white.  But, if I apply any transparency to the brush via surface flags, the whole texture is semi-transparent BUT any place with the alpha color is fully transparent.  It looks more like quake 2 either must to the whole thing partly transparent to support an alpha draw for models/brushes.  Sprites support alpha though.

I was hoping it was like doom 1/2 which did alpha on nearly everything. 

[QwazyWabbit]

If moveable items can't have transparency how did they make the breakable window in base1.bsp? I'm not being a wiseguy and I don't know how it's done, I'm just asking the question.

[Whirlingdervish]

If moveable items can't have transparency how did they make the breakable window in base1.bsp? I'm not being a wiseguy and I don't know how it's done, I'm just asking the question.

That's a good question!

By moveable entities I meant player models, weapons (they spin) and things like doors or func_trains, but I hadn't thought about that specific application.

Apparently the func_explosive entity can have transparency on it's brushes, because when it breaks the game just creates fake little bits and chunks (temporary entities) to simulate something solid being blown to pieces, as opposed to moving the brushes with the transparency themselves.

That trick was done by making about 4-5 brushes that together make up a square window, but which when seperate look like broken pieces of that same window. They just took those brushes, and stuck them into a func_explosive entity/group and then applied the window and trans33 surface flags to the brushes to make a transparent window that when hit for a certain amount of damage would dissapear like a func_wall that's been turned off and simultaneously spawn a bunch of little bits, simulating a breaking glass window.

It looks like so if you open the .bsp in QuArK:

[The Happy Friar]

I can't get a func_explosion to even show up!  Strange... fresh install of GTK radient on my wife's comp.  Plus, with a "trans33" or "trans66" flag blaster fire in front of the texture appears partly transparent.  The window in the first map doesn't do that.  Strange.

[The Happy Friar]

Things get weirder & weirder... 

on my computer I can make glass, can make it explode & the projectiles in front of glass look just fine.  My wife's computer didn't.  ?????

I also added a translucent renderFX to the insane guy.  On my wife's comp he wasn't translucent but you could see other parts of the model during certain points in the animation.  On my computer he doesn't show up at all! 

so I did another test.  I added the translucent renderFX to a custom animated md2 I made.  nothing special, it's a door that animates open when triggered.  It's translucent, even when animated!   I changed the bounding box type, didn't matter.  I changed the movetype on the insane guy to none vs step, didn't matter.

so Q2 displays moving translucent md2's just fine!  You can see the insides but that's no different then non-moving entities.

[Whirlingdervish]

I think in the dm game mode, the func_explosive will not appear.

It may be reserved for single player.

[The Happy Friar]

Q2 with alpha test texture & brush support:
two sided US flag, animated:


trees.  trunk = 1 model, leaves = 2nd model.



brush with alpha test:


fire hydrant w/alpha'ed chain:


back of road sign (front in trees image):


Uploaded with ImageShack.us

The leaves/bark textures I used from cgtextures, the low quality thumb.  I didn't want to make my own just to test some theories.  The fire hydrant I used pic's of a local hydrant, the US flag is a genc, 3 color flag I found via google/yahoo.  Sign was the same thing.

[[BTF] Reflex]

Trees are badass,  makes me want to go out and map

[The Happy Friar]

trees are a pain.  I made then in blender with a tree generator but I had to manually fix ~1/3rd of all the triangles because when I reduced the poly count (decimate) it apparently disconnected some of them (or they weren't connected to begin with!).