Razorwing's Ice

[Razorwing]

I've created an ice layer model, intended to be used in chilly parts in Silgrad Tower. -Here is a video- of it. The screenshot doesn't really do it justice, since it doesn't convey the reflection and refraction.

Ever looked into a block of ice while passing by it and noticed how weird it looks? I did that a few months ago. It's almost as if the top of the ice is moving more slowly than the bottom part of it is, similar to the effect of looking out of the window of a moving car where the stuff at the horizon looks like it's moving more slowly than the street next to the car. I wanted to emulate this effect and figured a good way of doing it would be to stack a few transparant surfaces on top of one another. I like to think it worked out even better than I had thought Walking across this ice is definitely a different feeling than walking across usual landscape.

I experimented with a lot of techniques like hilights (the glass effect) and environment maps (advanced reflection), but they detracted from the effect of the transparancy. This is the solution I decided looked best for what I wanted to achieve.

There is one slight problem, as you can see -in this image-. The sheets of ice don't tile very well, and these weird effects show up along the edges of sheets placed next to one another. Undoubtedly it's related to the transparancy. I don't think it's a huge problem, I made three different sizes of the sheets, but it would be nice to know that should one wish to mod a large, frozen lake several cells large then one can do so without these graphical glitches. Is anyone familiar with the bug and know how to solve it? (The sheet is made up of six layers that all have 4845 transparancy flags.)

The textures are freeware that I found on the Spiral Graphics site.

[TheImperialDragon]

One comment: :pop:

:applause:

[nick_op]

Originally posted by Razorwing
Is anyone familiar with the bug and know how to solve it? (The sheet is made up of six layers that all have 4845 transparancy flags.)

I think that hair meshes have some sort of triangle sorting to avoid such a bug, I think it might be a Material Setting name. Of course, the mesh has to be built in such a way to facilitate proper sorting, but I believe the problem is solvable.

I don't fully understand it myself though, so I'll point throttlekitty in this direction as he has more knowledge on this kind of thing than I do.

[Ibsen's Ghost]

Marvellous! You must, however, get the most out of it though. If you can somehow get the ice sheet to crack in places when you walk over it then you can have the player fall into a special water type that saps your health. It would be great to also have the experience of being trapped by ice, if that's possible (but not in RL =)), or to be forced to swim underwater to some form of safety point i.e. an underwater cavern. In other words, the player would need some way of escaping it for it not to be annoying.

I know the idea regarding the water type is dead easy because I did the same sort of thing with BM recently but is the idea of having a proper 'layer' that is capable of cracking in places doable?

[Razorwing]

TheImperialDragon: Thanks

nick_op: That's interesting to know! If it's because of triangle sorting, wouldn't it be odd that the glitch only appears very near the edges even though the sheets are just two faces per layer? It'll be interesting to see what information throttlekitty might share with us

Ibsen's Ghost: It's impossible to make cracked ice with the technique I'm using since it only looks threedimensional from the top and bottom. In theory one could make a hole in the ice through assembling the small sheets in a tileset fashion and covering the sides with snow boulders to allow the player to swim under the ice. There's a few Jeral Mountain rocks that could do the trick. Currently I wouldn't advise trying to tile the sheets due to the graphical glitch I mentioned. Or one could have a modded cave with a secondary exit that leads to the underside of a frozen lake, with no way to reach the surface other than going back into the cave. If that's coupled with constant damage from the cold water I think it could be a rather nice challenge in an adventure.

[Zurke]

Great Job RW

[nick_op]

Here's what throttlekitty had to say:

Originally posted by throttlekitty
So, for Razorwings mesh, it's hard to say what's going on there, but it really doesn't look like depth-sorting problems, but it could be. It looks more to me like z-fighting; I assume that there's a few layers of flat planes atop each other, set up in a grid via the CS. It looks to me like the grid is overlapping at the edges.

However, if those planes have a good vertical distance for the effect, I suppose that there could be transparency issues, but if they are multiple instances set up in the CS, there isn't much we can do. There isn't a way that I know of to control draw order across multiple objects, especially if they have multiple layers like this. The underlying issue is the renderer draws things in order, from back to front; typically first by sorting objects from back to front based on the camera (then draws each mesh by the vertex order, starting from zero). With that said, the renderer blends transparent pixels based on this order only, so if the 'behind' area is drawn after the 'in front' area, there's technically nothing to blend with, you dig? (objects not considered for alpha blending aren't subject to this treatment)

The 'trick' to making hair is in the construction of the meshes; ensuring that Farther/Underneath verts/triangles have a lower number in the vertex index than Closer/Overlaying verts/triangles. This is best done with the various planes as separate meshes, and selecting/combining them in a back-to-front order. There is a 'magic' material used in Oblivion, named 'dynalpha' there's a couple of meshes that use it; and seems to suggest that it somehow circumvents the triangle sorting, but I could never get it to work that way. I did get an interesting "peel away" effect in my tests though, so it's something he might want to try out. My, aren't I verbose today?

And also this:

Originally posted by throttlekitty
Oh, and that's a pretty darn spiffy effect, if you could relay that as well.

Ibsen's Ghost: I like the idea of the ice cracking - it's certainly doable. It would require a new mesh, of course, but there's no real complexity involved.

[Ibsen's Ghost]

Thanks, nick_op! It depends on whether RW is interested in such an effect, I guess.

Personally, it's got me thinking about whether creating something like quicksand for BM would indeed prove possible....

[Koniption]

Hahaha, that's a neat icy effect you got there. Looks really good.

@ Ibsen - Quicksand, eh? Hmmm, might be possible. What you might could do, is sculpt the landscape to have some deep pockets, then cover the pockets on the top with a "quicksand" texture on a flat or slightly bumpy mesh. You could try to make actual water in those pockets, by selecting the cell to have water, and maybe add a dark, opaque water shader so the player can't see below water. Have a trigger collision box/mesh at the bottom of the pocket, underwater, that kills anything that touches it. Then have a script that slowly pulls the player downward on the Z-axis (vertical axis), so that the player has to struggle to stay above water and not sink too deep, else they die. Or you can omit the trigger collision, and just use the script to pull them down, while depending on the "underwater oxygen meter" to run out to kill them. Heck, you can make it so heavier armor and inventory pull you down faster in the quicksand.... just some thoughts.

Koniption

[Ibsen's Ghost]

Wow! So it's possible and highly adaptable then....? Perhaps this is something we should explore. Anyway, probably best not to hijack RW's thread here with our discussions on this matter unless RW is okay with it....