Ice and friction

[grayman]

Is there any interest in reducing friction on ice to make it slippery?

 

Or is it already slippery and I just haven't noticed?

[rich_is_bored]

There's a material shader keyword called slick that will do the job.

 

http://www.modwiki.net/wiki/Slick_%28Material_global_keyword%29

[grayman]

Thanks.

 

Looks like we don't use it on our ice textures, and it only applies to the player.

 

I'll test it and see how it behaves.

[Serpentine]

iirc slick doesnt work correctly, think they even mention it on iddevnet. That said, might be a good idea to have a slick nodraw if it does work

 

If only I was able to launch 3d apps/games without crashing, arrrgh

[demagogue]

Yeah a no-draw overlay is the way to go.

[grayman]

I've confirmed that it doesn't work correctly, and filed issue #2409. I'm looking into it. I will admit to a childish desire to bounce off walls.

 

The ice and nodraw_ice textures would normally get this.

 

Are you asking for an independant slick overlay that you could add to any texture? Perhaps to create a slick slope of stones near a stream?

[demagogue]

Are you asking for an independant slick overlay that you could add to any texture? Perhaps to create a slick slope of stones near a stream?

 

That's one thing no-draw textures are good for. You could make anything slippery.

Or just if you want one kind of ice texture to be slippery but not another.

It's a fast way to pick & choose.

You still need the right sound to go with it, though.

If there's already an ice no-draw texture, maybe that's good as it is.

[grayman]

That's one thing no-draw textures are good for. You could make anything slippery.

Or just if you want one kind of ice texture to be slippery but not another.

It's a fast way to pick & choose.

You still need the right sound to go with it, though.

If there's already an ice no-draw texture, maybe that's good as it is.

 

tdm_nodrawsolid_ice already exists. I gave it 'slick' and now you slide around realistically. The footsteps are 'walking on ice' sounds, which I think is okay regardless of what's underneath.

"Slick" means:

- when you're walking or running, it's like normal walking or running

- stopping is no longer sudden; your momentum stays with you and falls off as you slide to a stop

- it won't make you fall down

I fixed the existing 'slick' code to make it work correctly.

AI moving around on ice should exhibit the same physics, but there's no code in place to do that. Perhaps something to look at in the future. Thrown objects like mines should slide along the ice and bounce off walls with wall-bouncing physics. Also future work.

 

 

 

 

[ungoliant]

that sounds cool. I'd like a copy of that to play with and try to make a big ski-jump and see how far i can launch the player.

[grayman]

that sounds cool. I'd like a copy of that to play with and try to make a big ski-jump and see how far i can launch the player.

 

Friction comes into play when you let go of a movement key. It defines how long it takes for you to come to a stop.

 

Reducing friction (via 'slick') doesn't make you walk or run faster. It just increases the time it takes to come to a stop. This gives you a sensation of slipperiness at the end of your movement.

 

Which means sliding down a "too-steep-to-stand-on" slope will just drop you off the ledge at the end. Then it's straight down, since you don't have any forward momentum.

[Tels]

Friction comes into play when you let go of a movement key. It defines how long it takes for you to come to a stop.

 

Reducing friction (via 'slick') doesn't make you walk or run faster. It just increases the time it takes to come to a stop. This gives you a sensation of slipperiness at the end of your movement.

 

Which means sliding down a "too-steep-to-stand-on" slope will just drop you off the ledge at the end. Then it's straight down, since you don't have any forward momentum.

 

Hm, but wouldn't the "sliding" moment (e.g. you move briefly, then let go and slide) never stop, because while you are downhill, ever more energy is put into you? I mean, you slide already downhill a roof, it it was tagged slick, would you slide faster? (If not, that sounds like something that should be fixed).

[ungoliant]

i thought it was self explanatory, if you've ever tried to jump onto a slanted roof with slick texture, you just slide right back down even if you try to run up it. i would think that momentum builds up over a distance.

[nbohr1more]

Yep.

 

Momentum should be emergent by function of the mass parameter

 

http://www.modwiki.net/wiki/Entitydef_%28decl%29

 

...based on how JC Denton explained the momentum behavior for bullets in his mod ?

[ungoliant]

also i vote that slick be given a new editor image in 1.03, pretty sure it just says "shader not found" in DR right now.

[grayman]

Okay, okay. My white flag's up and I've ducked behind the ramparts.

 

I know all this stuff should be there. I took a breather from learning how movement works (for the "stuck AI" bug) for a day and got this little piece of existing 'slick' code to work correctly (on flat surfaces).

 

The next time I need a breather ("stuck AI" will take a while I think) I'll add the momentum stuff and then you can build a proper ski-jump or death slide or whatever suits you.

[grayman]

also i vote that slick be given a new editor image in 1.03, pretty sure it just says "shader not found" in DR right now.

 

'Slick' is just an attribute added to the ice and ice nodraw shaders. It's not really a separate shader (like dry and wet surfaces that have different speculars), so it doesn't have a separate editor image.

[nbohr1more]

 

Pay no mind to my "peanut gallery" comments. I just like to throw links and resources out there in case they might help. I'm happy that you have it working at all.

[ungoliant]

'Slick' is just an attribute added to the ice and ice nodraw shaders. It's not really a separate shader (like dry and wet surfaces that have different speculars), so it doesn't have a separate editor image.

 

textures/common/slick

 

didn't know that it was just a keyword though. never really bothered to read the shader definition.

[grayman]

textures/common/slick

 

didn't know that it was just a keyword though. never really bothered to read the shader definition.

 

The comment on that material in the Doom 3 files is:

 

// slick is an invisible surface that should be

// used as a thin sliver brush over floors to cause sliding

 

So I think it's okay for there to be a "shader not found" in DR.

 

I didn't know about this one (thanks for pointing it out), and will test it tomorrow.

[Serpentine]

I've been messing around with the idea of generating placeholder textures for different nodraw versions as such, I find it pretty hard to work out what's going on in some more complex scenes. I have it generating random checkerboards with the relevant name on them, I just need a way to spot them more easily and hopefully I can sort out an editor's PK4 with a full set.

 

Ideally once they're easily Identified I can throw some comment into the material to generate them automatically from some values, i.e preset colors and human readable names. For stuff like rocks etc, since there are only so many colors, I think I'll use a generic rock texture and then put a checkerboard over that with the name, help break things up.

 

Anyway, a bit off topic but an idea.

[grayman]

I tested textures/common/slick and it works as advertised.

There are no footstep sounds when you walk on it, though. I thought there was a default footstep. Something else to look at.

[grayman]

I've made changes to support 'slick' on sloped surfaces.

 

Now, depending on the slope, you will pick up some acceleration. Less slope = less acceleration. More slope = more acceleration. After the slope rises to 1/2 (1 'rise' for each 2 of 'run') you won't be able to walk up it. (As a reference, you can't walk up regular ground if the slope is above 1/1 (roughly).)

 

I'm not planning any further changes.

[Mortem Desino]

The default "no material" footstep sound was changed to silence awhile ago. If the player somehow stepped on plain nodraw, caulk, etc, the default step sound was very loud and propagated so far that it annoyed AI rather far away.

 

I took a quick look at the SDK changes you made. Looks pretty slick. </pun>

[grayman]

I took a quick look at the SDK changes you made. Looks pretty slick. </pun>

 

Shiny.

[Aprilsister]

So glad you took the dive into helping out as a programmer! Tremendous.