Bendy pipes on yer choofers (and other fancy stuff)

[Gumboots]

Been thinking about this lately, for situations when I want to do pipework with graphics instead of verts. For instance, that revamp of the BR39 I was playing with back before we could use Blender. It wouldn't be that hard to finish now, but needs a lot of fancy pipes stuck to the boiler, etc.

My PS skills aren't that great, but I found some tuts which are very helpful. Obviously I had to sort through a lot of crap ones before finding the good ones, but you get that. I figure having a thread to link up handy tutorials for all sort of skinning niggles would be useful. Doesn't have to be just Photoshop of course. Tips for any app would be handy.

Basic straight pipes are pretty easy.

Curved pipes are trickier, and had me stumped. So this tutorial, which I haven't tried yet, looks very useful: How to Create Bent Pipes in Photoshop. Obviously the advantage of this one is that you can lay out any complex path quickly and easily with a few mouse clicks.

This one looks great for if you need corrugated pipes around a bend: Segmented Pipes.

This last one is nifty too: New to me! Gradient on a path! This one lets you get a gradient that follows the pipework around any bend. The result isn't perfect at large scale, because the shading of the gradient follows the pipe around instead of changing as it would with a real light angle, if that makes sense. However, it's good enough for a general effect on small scale skinning work.

The only catch here is that even if the path is laid out with a solid colour (such as using the line tool set to green at 100% opacity) the application of the stroke/gradient/shape burst trick somehow renders the line translucent**. This is a problem for pipes the cross each other, or where you have a changing background colour beneath the layer. To get around this, I found it necessary to have a duplicated layer underneath the pipe which was just a plain solid colour. That fixes it.

**Edit: Ha! I figured out why the pipes were going translucent. Some idiot had left his stroke blending mode on "Multiply". Change it back to "Normal" and the pipes are nice and solid, just like they should be. Then you don't need the extra layer underneath.

To make that one, I used this trick to add straight extensions on the curved bits: Merge Photoshop Shapes into One Combined Shape.

Edit: and this looks handy for doing lotsa rivets: Rivets: The easy way.

[Gumboots]

w00t!

So I tried the rivet idea and that works a treat. Was able to create this in about ten minutes of messing around.

Which then got some pipes thrown on top for a test run.

So ok that's a start. Then I got thinking about planks, like for the sides of wooden-bodied cabooses or whatever. I figure there had to be a quick and and easy way of laying out plank lines. There is. This is it: Creating series of horizontal lines in Photoshop.

Using that trick, which will obviously work with vertical lines too, and presumably with diagonal lines, I was able to lay out a sequence on plank lines in no time at at all. A bit of playing around with styles generated this, which has potential.

This is all simple stuff that lots of people obviously knew, but which I had no idea about.

[Gumboots]

Did a quick test of this method...

Curved pipes are trickier, and had me stumped. So this tutorial, which I haven't tried yet, looks very useful: How to Create Bent Pipes in Photoshop. Obviously the advantage of this one is that you can lay out any complex path quickly and easily with a few mouse clicks.

Ok, it works. It works well.

The lump in the pipe near the second bend is because my mouse is about to crap out, so the selection went wonky there. Good enough for a quick test, so didn't worry about it.

Figured out a couple of tricks. Dropped a duplicate layer on top of the one produced by the method in the article. Set a scratchy steel pattern (small scale and fairly low opacity) and some Gaussian noise on that, which gave a pretty good steel pipe look quite easily. Then used the old bevel and emboss and messed with its settings some. That's improves things because it gives the effect of proper highlighting from a given light direction. Which is cool. So I think I can do basic pipes now.

Edit: Played around with this some more. The same basic techniques will be good for thing other than pipes too.

[Gumboots]

Two more good links. I found them for doing other things (fancy curvy bits on the sides of A era pax cars) but I can see they'll also be very handy for pipework and all sort of things.

http://www.photoshopessentials.com/basi ... -subtract/

http://www.shapes4free.com/photoshop-sh ... ned-shape/

[Gumboots]

I just realised something which should have been obvious before. The warp tool in Photoshop (and presumably GIMP is the same) uses a percentage of warp where 100% corresponds to a 180 degree bend. So 50% warp is a 90 degree bend, 25% warp is 45 degrees, etc. This is great for making pipework on choofers.

The idea of using a path and starting on the alpha channel (mentioned here) is good in that you can lay out a complicated path with a quick series of clicks, but bad in that it tends to make lumpy pipes and uneven bends if you're not very careful.

OTOH, the warp tool always gives totally clean results. The pipe will keep a constant diameter around any bend. Since straight sections between bends can be easily added by using the line or rectangle tool on the vector's layer mask, you can make almost any pipe path pretty quickly and easily.

Probably both methods would be useful at different times, depending on what you're trying to do. The first method is faster if it'll work without distortion (will for some examples) but the second is more bulletproof.