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View Full Version : Alpha Map Chains in video games?


1magus
08-15-2011, 08:37 PM
So I have tried to find some tutorials on this but unfortunately I keep finding chain link fence tutorials. Now I know how to make alpha maps in games and in photoshop but I'm not sure how to make a simple chain, I just don't know how to begin modeling one do I just use plains, 2 boxes that form a cross?

Btw by chains I mean like what Kratos's weapons are hung by or something you typically see in factories to transport things.

I was just wondering if anybody had some useful tutorials or advice?

Brendan
08-15-2011, 09:38 PM
It really depends on how big the chain links are, how many of them there are, and how much screen space (and how often) they'll take.

For the Kratos chains, you can sorta cheese it with the transparency, you might be able to make it work with just the transparent planes, but the links themselves have to e small and take up little screen space. If it's going to be bigger, and you can afford it, perhaps you could mix the alpha approach and a poly mesh and use that.

http://i700.photobucket.com/albums/ww5/TBR427/chains.png
Heck, you could probably get away with a 16x16 for the links here...The advantage to this is that half your chain links don't disappear when you view the thing from the side, as they would with a purely alpha chain. You can sort of billboard the things, at each edge (like Unity's trail renderer, or the ropes in Half Life 2), but they if you're going around it it never turns.

If you're feeling especially cheesy, grab the verts on the center face on my example and merge them, re-UV and you can save a few more polys, while maintaining some depth.

For larger chains, just model the things. That always gives it that much more depth.

Ben Apuna
08-15-2011, 09:50 PM
Chains. When to plane when to model (http://www.polycount.com/forum/showthread.php?t=74502)

1magus
08-15-2011, 09:52 PM
Well yes if it is a giant chain like bigger than the player character I would imagine you model them lol. But the ones I need to make are small chains that support things like lamps, torches, hanging dead bodies etc..

1magus
08-15-2011, 10:03 PM
Ok I'm trying to understand this but than it says this is 160 polygons per chain which makes no since to me. From what I see you model 2 diamond shaped boxes, than place them into each other and have them with a chain alpha map texture that curves around each side? Or am I way off?

I really need some help on this one cause I cannot model the chains out lol.

Brendan
08-15-2011, 10:14 PM
You're sort of there.

Make a box, rotate 45 degrees. Grab the edges on the far left and right, and scale them outwards. Then planar map them (UV - planar map, or el cheapo make sure you're looking through the right ortho camera and UV - based on camera).

Go into photoshop, make a chain link looking thing at a low resolution (in this case maybe 32x32, maybe 16x16). Make sure the bits that aren't metal are transparent. Also only do one or two chain links, you can use this as a repeating texture, but if you're not game just do one.

Apply that texture to the model, find the tiling options in your program of choice and set them so they look right for the length of chain you have. Then duplicate the thing, rotate 90 degrees, and you've got it.


One animating thing you could try, is make a bone, and play with the weights you can apply. Add in some edge loops and have a gradient and you'll get some curve, or make the whole thing attached to the bone and you'll keep the chain taut and straight. Or maybe go with something in between.

Also, if you can, even fake a normal map for the chain. That halps give it the depth on the inside of each chain link I think.

1magus
08-15-2011, 10:36 PM
I think I've got what you are saying. When I finally did learn how to UV map things I did not really use UVW mapping at all ( I use 3ds Max ) so to me this is going to be some experimentation. I tend to make my model than use the UNWRAP method so I make the UV map my self but I never learned the difference between UNWRAP and UVW.

This is just a guess but I'm assuming
UNWRAP means you take a complex model or something that you can't easily make a repeating texture for and make the UV map you're self than texture
and UVW is for repeating things like a tiled floor or my chain

Is this true? It would greatly help me if someone could answer that as well lol, there has been some confusion when I model things.

Also how far do I take out the left and right edges? I took each edge with the move tool and took them out 10 units each, do you think that works?

1magus
08-15-2011, 10:45 PM
Sorry if I made this a lot more complex but tileable things are rather new to me, I know how to make them but they can be quite challenging.

1magus
08-16-2011, 08:50 PM
Ok so far I have this lol, I tried various methods but I can't get it to work right.

1magus
08-17-2011, 01:13 PM
Bump I need some help pleeeeeeeeeeeeeeease

1magus
08-17-2011, 07:46 PM
More bump?

Ben Apuna
08-17-2011, 09:15 PM
You should use two intersecting meshes offset from each other with one rotated 90 rather than the one mesh you are attempting to use. Take a closer look at the example in the link I posted.

Something like this:

http://i583.photobucket.com/albums/ss273/bapuna/chainMesh.gif

Ghostscape
08-17-2011, 09:18 PM
Have you never UV mapped before? Learn how to use the edit UVW modifier and unwrap something properly.

Alternatively you can get to where you want to be by rotating the gizmo for the planar map you have there.

1magus
08-18-2011, 11:07 AM
Yes I know how to unwrap and uv map things. But I thought for something like this I was supposed to use the UVW map modifier since it is just a repeating texture?

I have used the Unwrap mod for every model that I make and been ignoring the UVW map one. I thought the UVW Map Modifier was used in games for repeating textures, or am I way off?

Also I have done that with the cylinders and offset one by 90 degrees I'm just having trouble with the texture lol.

Justin Meisse
08-18-2011, 02:52 PM
The texture repeats outside of your 0-1 square in the UVW editor window - tiling textures do not require you to use UVW map modifier. So, to have the texture repeat, just stretch your UVs outside the UV square

1magus
08-18-2011, 04:04 PM
DO you mean this window? I had no idea you could make textures repeat by scaling them outside the box?

And please do not call me a noob lol I did learn to unwrap things about 6 months ago which was about the time I started to get extremely serious about modeling.

How do I make a texture repeat in it though I mean all my UVs need to be in that purple box so how do I tell the UVs to repeat outside that box??

1magus
08-18-2011, 04:13 PM
Right now this is what I have, I can redesign the texture from a new render UVW template file but I don't know how to get it to tile lol.

1magus
08-18-2011, 04:51 PM
I figured it out, man I feel dumb for not knowing I could do something like this for so long. Are there any advanced tools in the mapper that help with tiling?

Snader
08-19-2011, 03:07 AM
That mesh you have right now is far more complex than what I had. Here's my mesh:
http://dl.dropbox.com/u/448525/keep/Polycount/chainscheap.png

My texture wasn't very efficient for a single prop. I made a strip of 4 links on the left 25% of the texture - my intention was a combined sheet and I would fill up the other 75% with similar strips, like rope and wires. I made it a 4-link strip so the swing (iirc the guy who asked about cheap chains needed it for a swing) could still have some gentle movement.

Ben Apuna: don't forget to offset the two meshes a bit so the chain links interlock properly.

Ben Apuna
08-19-2011, 09:21 AM
@Snader:

Oops! :poly136: Nice catch on my error. Yes my example geometry would definitely have issues. (that's what I get for rushing something for an example pic...).

@1magus:

I hope I didn't lead you astray with my pic.

1magus
08-19-2011, 11:28 AM
Well I made mine curved because when the texture was finally applied properly to the rotated boxes it looked horrible. How would I animate those anyway? Add animate bones? I mean I have animated things before but not for games yet and I'm not sure which method is well video game engine friendly?

Giometric
08-19-2011, 11:53 AM
Yeah bones will be your best bet, you may need to subdivide the mesh a bit to make sure it has enough points to actually deform. How much you have to subdivide it depends of course on what exactly the chain will be doing.