Vine Arrow

[Springheel]

There are still some technical things about how to make this work, but now that we've got the generic climbing thing mostly done, we need to get the art assets ready. Mikebart has the basic textures done for the vines, but we have some decisions to make.

 

We decided a while back that decals seem to make the most sense. I don't know much about decals, but here's what we want to accomplish:

 

1. Ideally, the vines should 'grow' from the point of impact. I don't know if this is possible with decals or not. TDS did it fairly effectively with the moss arrow effect, however. If a growing effect isn't possible, then the second option would be some kind of particle effect that bursts on impact, and then the decal appears.

 

2. The vines should appear upwards and outwards from the point of impact, ideally, as if the vines were growing. I imagine that it's possible to make sure the decal is not centered on the point of impact, but I have no idea.

 

Anyone know enough about decals to figure out whether these are possible?

[OrbWeaver]

I don't see why you can't combine the particle and decal effects, since particles are subject to lighting and can use arbitrary textures, including decals. A multi-stage particle effect might be able to produce both the "burst mist" and the growing vines.

[Ishtvan]

We already established that decals sitting on something else will get hit first by a trace and be distinct from the texture underneath, right?

[OrbWeaver]

That's a thought. It may be that using a particle would prevent the necessary physics calculations, since I suspect particles are non-physical.

[Domarius]

TDS didn't use decals - they were just seperate meshes.

 

Decals are plastered onto the surface - they use the same geometry as the surface.

[Springheel]

We already established that decals sitting on something else will get hit first by a trace

 

I'm not sure if anyone actually tested it, but someone who sounded like they knew what they were talking about said it would.

[Springheel]

TDS didn't use decals - they were just seperate meshes.

 

I didn't think they were decals. How did they get them to 'grow' though? Can you dynamically resize meshes in TDS?

[angua]

How have you planned spawning the vines? Did you plan to create a particle effect together with a decal? I could play around a bit with particle effects and see if I can come something.

[Springheel]

We don't have a firm plan in mind, which is why I'm bringing it up again. From previous discussions it seemed like decals were probably the way to go, as they would adapt themselves to fit the world geometry, where meshes would not. But that's as far as we got.

 

We have Mikebart's ivy texture: http://forums.thedarkmod.com/index.php?showt...=4817&st=25, so if you'd like to take a shot at putting an ivy effect together, feel free.

[OrbWeaver]

Decals won't adapt any better than a mesh, because a decal is just a texture -- you still have to create the geometry yourself to apply the texture onto, which means the problem of matching to the underlying terrain is not solved.

[Springheel]

Hmm, I just accepted that this was true, but I think you're right. When you shoot a fire arrow into a corner, it only puts the decal one one wall, not both.

[Crispy]

I didn't think they were decals. How did they get them to 'grow' though? Can you dynamically resize meshes in TDS?

Sort of. There's a "DrawScale" property that lets you change the size of the render model. (It doesn't change the size of the collision mesh though, which was quite annoying.) They could have used the same functionality to make the model look like it was "growing".

[Springheel]

Well, I'm willing to open the floor on this one again. What do people think is the best way to accomplish the growing vine effect? Especially given that we would want the vines to be able to grow from one vertical surface to another?

[Crispy]

Re: particles - I assume everyone is talking about them with regard to graphical effects only, since I didn't think they could have any effect on physics. A "burst" particle effect when the vine arrow impacts would be nice though.

 

Especially given that we would want the vines to be able to grow from one vertical surface to another?

Doesn't sound like decals would work in that case then. They just use existing geometry, right? So you can't have a decal extending past the edge of an existing surface.

 

There are some flexibility disadvantages with models. How would you do a proper "vine growing" effect without resorting to an actual animation? (Complete with skeleton and rigging - like the AIs work.) I can't think of a good way to do it otherwise without it looking somewhat faked. e.g. You could fake it by just spawning each piece of the vine individually, going upwards.

 

If D3 can also scale it as it appears, that might look OK. Maybe also try adding a green particle effect which goes upwards and is triggered every time a vine piece is spawned, giving the impression that the vine is somehow sending tendrils upwards to spawn each new piece.

[Domarius]

Sort of. There's a "DrawScale" property that lets you change the size of the render model. (It doesn't change the size of the collision mesh though, which was quite annoying.) They could have used the same functionality to make the model look like it was "growing".

Well if we did the TDS way, which appears to be having a dome mesh thing and dynamically resizing it bigger, then all we'd have to do is model it at full size, including the collision mesh, spawn it during the game, but start the visual mesh at a scale of 0.01 and scale it to 1.0 quickly to fake the growing effect. No one will notice the collision mesh is already at full size from the moment it spawns because the growing effect would happen so quickly.

[Crispy]

Well yeah, that's the idea.

 

I've been looking through the SDK though, and I don't see anything that would let us change the size of the model programmatically.

 

Couldn't it just be done with an md5 animation? Just animate it scaling upwards from 0.001 scale to 1.0 scale. It'd take about 2 minutes to create.

 

Edit: Never mind, I just remembered - we can do this, by manipulating the "rotation" matrix so that it does a scale. Dunno if you can do it from script, but we can create a new scriptevent if not.

 

Heck, it's even in the wiki. http://www.thirdfilms.com/darkwiki/index.p...Resizing_Models

 

See also http://www.doom3world.org/phpbb2/viewtopic.php?t=15227

[angua]

I've played around a bit and made a little particle effect. The effect together with a map is on ftp:

 

http://208.49.149.118/TheDarkMod/maps/test.../vines_test.pk4

 

(already compiled, just type "map vines_test")

[OrbWeaver]

I don't think TDS resized the mesh, I think it spawned a number of smaller "domes" in the same place and then moved them outwards, giving the impression of a growing vine cover but not actually requiring any individual mesh to be resized.

[Crispy]

Nice particle effect! We definitely have to use that, or something like it.

 

Orb: Are you sure? I guess they could have done it that way, though it doesn't sound like a very good method. My TDS installation isn't in a usable state so I can't check.

[OrbWeaver]

I'm not absolutely sure, no, but I do remember it looking a bit like this and it would solve any issues with mesh resizing which tend to occur. Not only does mesh resizing upset the physics, but it would also result in the texture scaling which would look odd -- the size of the vines shouldn't really increase, just the number of them.

[Crispy]

I don't think the physics is a problem. IMO it's a good thing that the collision mesh stays the same size, because it means you can climb up a vine while it's still growing without any risk of weird stuff happening as the surface you're grabbing on to moves around.

 

Anyway, vines do get thicker as they grow, to some extent. And if we use a nice particle effect like the one angua posted, I think it'll cover up any weirdness.

 

What we need is for someone to implement this. Then we'll all see that it looks fine and we can move on to another subject.

[Ishtvan]

Would it make any sense to fake a propagation effect by sending out multiple invisible projectiles from some focal point (air burst from some point farther back along the arrow's path from where the arrow actually hits)? The projectiles would just be used for accounting purposes, invisible until they hit the wall and caused a vine growing decal/effect. The ones diverging more to the edges would be launched later or move slower than the ones directed toward the center (arrow impact point), to produce an illusion of growing out from the center over time. Also, you could set the distance that they travel so that they wouldn't stick on things much farther away than the spot the arrow hit, since we want to maintain the illusion that it's a continuous vine layer. Just a thought.

[Crispy]

Hmm. Could work I suppose, though I'm wary of edge cases. Not that I can think of any problematic cases off the top of my head. You would get vine pieces not looking connected sometimes (where there's complicated geometry, or odd slopes), but that's not fatal.

[Springheel]

Would it make any sense to fake a propagation effect by sending out multiple invisible projectiles from some focal point

 

I had that thought last night too. I'm not sure how else we could have the vine attach to surfaces at different angles.

 

The problem with using meshes, I think, is that they'll stick to any surface, no matter how big it is. You could get ridiculous-looking situations where a vine hits a thin pole, and grows out several feet into the air on either side of the pole. Decals wouldn't do that.

[PinkDot]

Where would the vine start to grow and which direction if an arrow hit the middle of a wall. Would it grow upwards or downwards?