Modelling and Saving Polygons Part 1

I'm going to split this into sections, I can't bare saving this as a draft over and over again for months trying to complete it, and never getting around to it.

Anyway, A lot of people are always asking about creating low polygon objects which look good; I'd like to think I know a bit about doing this as I spent a long part of my younger nerdy life making model and object mods for the game Rollercoaster Tycoon 3. This is a proper old-school 3D game compared to most games these days; to the extent that any number of polygons saved could be a major lag-saver (due to the grid-spamming mechanics). I'm pretty sure I once made a chair of around 10 polygons... That's how military it got.

Disclaimer/Info

For a start I'm going to be teaching you wrongly. When I refer to a "Polygon" in this text (and in life) I'm ACTUALLY referring to a "tri"(triangle). A REAL polygon is an 'n-sided shape' (basically any shape with any number of sides). When I used to model, tri's and polygons were practically the same thing because EVERYTHING was split into tri's, and therefore, calling them the same thing didn't matter too much. These days you an get quads and upwards - I'm not sure if they are still calculated and split into tris, but it shouldn't matter too much because less polygons = less tris = more efficient.

Do you want to know how many tris your model has compared to polygons? Open up editable polygon mode, select ALL the vertices and press "connect" if your model is the only thing in the scene, the counter (found by pressing "7") will display the tris rather than polygons, this is often messy so you might want undo straight after you've looked.

Anyway,  few tips and tricks;

How Round?!
Usually people over-estimate the amount of sides that they need on an object; I would say considerately so. The general rule I use is that you shouldn't generally use more than 12 sides on most objects - some exceptions occur if it is a large object or a object of particular speciality, but in general, it's a good rule.
A good thing to know is often an odd number of sides is less noticeable than even numbers at low side counts - and can completely change the look of something. Even a smoothed 4-sided cylinder looks square, but change it to 5-sides and it can look twice as round.

Making Ends Meet
Do you need the ends, bottom or top of your object/sub object? Generally you don't need the bottom if it is on the floor, or the back if it is against a wall; simply taking the ends off things can take 8-12 polygons off at once (usually minimum). Do you really need a cube for a wall? If you use a plane instead you will cut the polygons by 83%. (especially good if it is repeated throughout a level).

Laziness

Remember you can change the values of everything when adding a primitive - and you should - normally things like cylinders have 5 height segments - You never usually need that many, like, ever. The best way to model is to have the lowest possible and add as needed, rather than trying to take stuff away after you've made it look good. remember if something is repeated, just a few polygons or tris saved will add up exponentially.

Texturing/Detail

Some things to bear in mind when modelling ready for textures;

• When you can, use Cut-out alphas or mask textures - they require less processing than transparencies; a cut-out or mask just doesn't render the parts you tell it not to, whereas a transparency does some weird merge and calculation and then changes the colours of the original texture to simulate transparency.
• Although transparencies require a bit more processing, they are still useful - don't be scared of using them instead of loads of polygons.
• Generally it's very good idea to convert polygon-detail to texture detail, but there is a cut-off point in which doing so becomes counter-productive; so don't start removing 5 polygons and replacing it with a 1024x1024 texture.

Polygon sandwiches are not very tasty, but they are very useful;

Sometimes this displays weird, ignore it if it does for you...

What's different about these tyres? Well, the rubbish mock-up textures are the same, they are the same resolution (too high, could be reduced) and they are both lit very badly, also, they were both made by me in about 10 minutes. The difference is that the tyre on the left is 68 tris, and the tyre on the right is 38 tris.

I would personally say that the tyre on the right looks more round, but the fact it saves 30 tris per wheel is awesome (540 tris saved on an 18-wheeler!). Why are they so different? The tyre on the left is a mapped cylinder, the tyre on the right is a cylinder with the front and back removed, and the front replaced with a plane; the alpha texture simply cuts around the wheel making it from square to round. (seen below). Really, it's a half sandwich because I didn't put a plane at the back,  but who needs a plane if it is always under a vehicle?!

The wheel actually has 18 sides, You could probably get away with 12... So I went against what I already said a bit already.

Replacing parts with alpha textures works with loads of things, you just have to dream it up; buttons on a control panel could be made to look raised by just having an alpha plane raised slightly higher than the desk for instance.

I'm going to cut this short, but beware more parts. Hope this was a little useful. (little because of not-finished-ness)