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#1 Old 21st Jun 2008 at 9:22 PM Last edited by Echo : 11th Sep 2008 at 12:20 PM.
Default Tiptorial: Low-Poly 3D Modelling - How and Why
What is this tiptorial for?

This tiptorial will help you understand:
  • What low-poly 3D modeling is...
  • Why it's important to make your models as low-poly as possible...
  • How to make your models low-poly...

This tiptorial is intended for creators looking for techniques to create better objects with fewer polygons. If you have stumbled upon this tiptorial as a downloader, or if you are an extreme beginner creator and need to know more basics about poly counts, see: What are poly counts? What's a good or bad poly count?.

What is low-poly modeling?

Low-poly modeling is simply using as few polygons (also known as faces or triangles) in creating your 3D model as possible - while still ending up with a high-quality, good-looking end product.

High-poly modeling is generally reserved for 3D renders - that is, items that are designed to be rendered as a still image, rather than played as a game. Low-poly modeling is used in games like The Sims 2.

Why is low-poly modeling important?

You could just model everything high-poly and not care about low-poly (and many lazy, irresponsible creators do), but there's some darn good reasons that everyone should strive for as low a poly count as possible. Here's a few:

Fewer Polys Means Higher FPS:
For every second your game is on your screen, your computer's graphics card has to plot the position of every item on the screen and draw it, multiple times in that second. The number of times per second it redraws the screen is known as FPS, or frames per second. The more powerful your graphics card, and the less work it has to do, the higher the FPS it can get. The less powerful your graphics card, and the more work it has to do, the lower your FPS gets. When the FPS drops too low, the game seems jerky or choppy and does not play smoothly - the lower the FPS, the worse this will seem, and too low a FPS will make your game seem basically unplayable - too laggy, jerky, and choppy to be enjoyable.

Fewer Polys Means Less Strain:
If your graphics card has to do too much work, it can end up overstrained and overheated. This is especially bad on lower-end graphics cards (which are used by many Sims 2 players). If you overstrain a graphics card on too much, it can wear it out much quicker, and can lead to the graphics card failing. On laptops, where you cannot change the graphics card, this can be disastrous, essentially ruining the laptop. Even on a desktop, where you can upgrade, it can be expensive to fix, and the heat generated by the overstrain can cause damage or failure in other parts.

Fewer Polys Means Less Crashing:
Too much strain on a graphics card can also cause crashes or driver errors. The game can freeze, crash, and can give an error related to a graphics driver failing. This is usually due to the graphics card being overworked and/or overheating. Crashes are often one of the first signs that a graphics card is becoming overstrained.

Fewer Polys Gives More Leeway Elsewhere:
Not every item has to be super low poly, but when you use low-poly modeling techniques whenever you can, it means your average poly count per item is reduced. When you only use just the polys you need and no more, it means that when you do need more polys for a more complex object somewhere else, you can feel more comfortable using them. Poly counts are a cumulative problem - one moderately high poly item will not cause issues. It's when you use a bunch that issues arise. So when you know most everything is low, you can feel safe using a few items that are a bit higher.

A good analogy is considering poly counts like a budget. If you have a higher-powered graphics card, you have a higher budget, but you still have a finite amount you can spend on polys. Each item you add costs a certain amount - its poly count. You may wish to spend more on very special objects that you might just use once or twice per lot, and it's okay to spend more on larger items than smaller ones.

When you keep the average cost low on the items you make, you leave room in the budget for more expensive items which may be worth the higher price. It's up to each creator to keep their poly counts as low as possible, and to not create items which are higher poly than they need to be (i.e. "overpriced").

Unlike in the real world, higher prices usually don't mean better quality, with extremely high prices being for high-quality fine designer merchandise - in fact, the opposite is often true in poly counts. It's often a sign of shoddy or lazy workmanship, or using incorrect techniques and not being respectful of your downloaders who are on a budget.

Techniques for low-poly modeling:

Now we get to the good stuff you really came here for... how do you create items that are low poly, yet still look good in-game?

Think about your sizing:
Whether a polygon is as small as a speck or as big as a house, it still takes the same amount of power to render... but most people play The Sims 2 zoomed out pretty far, only zooming in relatively close for stories, pictures, contests, etc.

This means that most items really don't need to look perfect when you zoom in extremely close, and items that will be small in-game can and should be much lower in poly count than larger items, where you'll be able to tell the difference.

So, for a practical example, a spoon and fork mesh that are meant to be big decorative items as tall as a sim to use as a statue outside a cafe would need to have a heck of a lot more polys compared to a spoon and fork mesh meant to be a small decorative item to sit on a table as part of a place setting.

Even for larger items, remember that you're not going to be zoomed in super close examining it for little imperfections, so it's okay if it's slightly blocky looking in your modeling program - it'll look just fine in-game. You'll look closer at your own work than anyone else will, so don't worry if it doesn't look absolutely perfect to you.

Think about your usage:
Some items are meant to be used only a few times per lot, and some you might use over and over. For example, a cool retro jukebox or interesitng statue you would probably only use once on a lot so they could be a bit higher poly... but a dining chair or shrub you might use many times on a single lot, so you would want them as low poly as possible.

You can take a look at poly counts for similar items made by Maxis to get an idea of what a good count will be for your item. But of course, remember that if you can go lower than Maxis, you should!

Plan before you start:
One of the biggest mistakes people make when modelling is just opening up their 3D program and going at it without really having a plan on exactly how it's going to be made.

It may help for you to try to sketch out on paper a few rough ideas of the shapes you're going to use and decide where you'll need extra detail. This can give you a basic idea of what your poly count will be like before you ever start... and is just a good idea in general.

You'll find the modelling process will tend to go a lot smoother, easier, and faster if you have a plan before you ever begin.

Just for an example, here's a nice turned leg that I might want to make a model of. It's a very complex shape, and being mostly round, it could easily end up very high poly. So I'm going to need a very solid plan before I start.

I'm doing my plan in Photoshop since I can trace right over, but you can do your plan on paper, or even in your head if you're more comfortable - as long as you have a good idea of how you're going to model without adding any extra polys.

I've decided to use a cube for the top squareish part, and a cylinder for the rest. I've tried to identify along the cylinder the main areas where the turning changes shape, and that's where I'll add detail. You'll note that I didn't put in every single tiny bump... that's because this is already going to be relatively high poly for a single leg, and I can always make the illusion of extra detail with the use of texturing.

I can count 15 divisions I'm going to need in that leg. This is quite a lot for a single leg, so I may want to revise my plan and reduce the amount of detail in it, especially if the rest of the object I'm making is going to need quite a bit of complexity too.

Don't use more polys than you need:
It sounds simple, but many people use a lot more polys than they need to get the exact same or a very similar effect in-game. Here are some good ways to make sure you don't use too many polys.

Reduce your number of stacks/height segments:
"Stacks" is the term often used for the number of vertical divisions in an item like a cylinder or sphere. You may need more stacks if you're creating a bent cylinder, but if you're just making a straight one, you probably only need a single stack. Additional unneeded stacks will add a lot of unnecessary complexity, and will add to your poly count.

Here's an example of two cylinders. Here, they're shown with a wireframe overlay, so you can see the polys. The left cylinder has six stacks, while the right cylinder has only one stack. The left cylinder has 112 polys, while the right one has only 32.

Now here's the same two cylinders, without the wireframe overlay. You can see that the two cylinders look exactly the same... despite the one on the left having 3.5 times the poly count of the one on the right!

112 vs. 32 may not seem like a lot, but when you consider that you may be duplicating a single piece like this several times for one object (like for four legs of a chair), unnecessary polys become a big deal!

In the picture of my plan for the turned leg above, you can see how you have to have multiple stacks - 15 by the way I had it planned. You can also see how this would end up with a lot of polys, so it may be worth sacrificing a bit of detail and reducing the amount of bumps and lumps to make it a little bit simpler a shape to go for a lower poly end result.

Here's another example. Sometimes you may need more than one stack if you're making something that bends, or doesn't have straight sides. However, you need to carefully consider how many stacks you're using depending on the application. Below are several cylinders which are bent at the same angle, but they have different numbers of stacks. They're labelled depending on the number of stacks, with the poly counts in parentheses below each one, and they have a wireframe overlay showing so you can see the polys.

Now here's the same cylinders without the wireframe overlay showing. You can tell a pretty clear difference between the first few, but as there are more and more stacks, the differences become more and more slight - but the poly count keeps going up. It's important to use as few stacks possible as you need, and to remember that if an object is going to be small and not very visible in-game, to use a very low number of stacks, since nobody's going to notice that it's not a perfectly smooth curve.

Reduce your number of slices/sides:
When creating cylinders or spheres, you'll also have the option of choosing how many "slices" or sides that item has. The fewer you use, the lower your poly count will be.

Here's an example, again of cylinders, showing cylinders with various numbers of slices per cylinder. The number of slices is on top, and the poly count for that cylinder is in parentheses along the bottom.

Without the wireframe overlay, you can more easily see the differences between the cylinders. Again, the differences are most noticeable in the low numbers, but as you add more slices/sides, the differences become more and more slight, while the poly count keeps going up.

While the differences in counts may not seem that great, this is just a single stack cylinder - if you needed more stacks to create a more complex shape, or you duplicate the cylinder multiple times in your mesh, the count quickly multiplies. Whenever possible, use low numbers of slices - for most applications you usually don't need more than 8, and for smaller items you can usually get away with 6, 5, or even 4.

Reduce your number of divisions:
In the previous examples, we've dealt mostly with rounded objects like cylinders. Rounded objects admittedly add poly count much faster than more boxy objects, but it's still important to be aware of your poly count even when you're using mostly straight lines.

Here's an example using cubes. The cube on the left has 8 length, width, and height segments. The cube on the right has just 1. You can see the polygons with the wireframe overlay.

And without the wireframe overlay... they look completely identical in shape and smoothness. The additional polygons add nothing but bloat to this cube!

While this is a pretty extreme example, it demonstrates a basic concept of low-poly modelling: when you're making something flat, it only needs the polys necessary to cover that area, and not a poly more!

Here's a less extreme example. Again, using cubes, this time modified so the top tapers in. The left cube has 3 vertical, 3 horizontal, and 3 width segments, making for a poly count of 120. The right cube has only 1 vertical, horizontal, and width segment, giving it a poly count of 12 - 1/10th the polys.

And again, the same modified cubes, without the wireframe overlay. You can see that again, they are identical. The additional polygons add nothing to the shape because the angle of the taper is constant.

Here's that same 3x3x3 modified cube, but additionally modified so the extra polygons do matter, and add to the shape.

Whereever there are more polys, the shape changes - the edges of the sides have a curved slope, the middles of the sides curve inward, and the top bulges outward. Each poly adds detail and thus, is serving a useful purpose. Make every poly count! If a set of polys aren't being useful, reduce them!

Change your technique:
3D modeling is far from an exact science, and for every item you can make, there's usually multiple ways of approaching its creation. Depending on how you've learned to create objects, you may use completely different techniques from someone else. The techniques you use can have a big impact on your poly count.

One of the easiest ways to reduce your poly count is simply to use simple 1x1x1 cubes whenever you can.

Here's an illustrative example. These two bookcases are the same basic shape.

The bookcase on the left is made by extruding and bevelling boxes. The shape is pretty much fully hollow, and each piece connects to each other piece as soon as it meets it. This is easiest to see along the back and sides, where you can see lots of individual polys as the shelves connect to the back and sides many times. On the fancy base and top, the horizontal parts connect at each corner to the vertical parts as soon as they meet them. This creates much more polys this way, for a total count of 300 polys.

The bookcase on the right is made by individual boxes put together. The back, sides, and shelves are their own separate boxes, as are the boxes of the fancy base and top. Any flat side is just a single two-poly plane. This way of modeling the bookcase creates much fewer polys, for a total count of just 144 polys - less than half of the other method.

It may be helpful if you think about how a real item like that would be constructed as if you'd purchased it in a store as a flat pack (like Ikea furniture) and were putting it together yourself. Think about the separate parts you'd be needing, and how they'd go together.

While both objects are still within the range of being considered low poly, this is a good demonstration of using only the polys you need and no more... Why use more than twice the polys to create the same shape when you can do it with much, much fewer polys and get the same effect?

Remove hidden polys:
Usually even if you build your models with primitives, you'll end up with hidden polys that aren't necessary. Any poly that won't show can be removed.

Here's that same bookcase (the 144 poly version). I've indicated where hidden polys can be removed without changing the look of the model. The basic principle here is that in this model, each box is a fully closed, 6-sided shape. Anywhere that a side will not show in-game, you can just delete that side, which will save you 2 polys per side you delete.

Because this diagram may be a little bit confusing, here's an explanation of everything that's being removed.

A: The bottoms of the boxes on the base, and the very bottom of the bookcase don't show at all.
B: The bottom of the lowest shelf can be removed, since you will likely never be looking at the bookcase from a low enough angle to tell that it's missing.
C: The tops and bottoms of the sides can be removed too as they don't show at all.
D: The tops of the boxes in the decorative top part don't show either.
E: The sides join up flat against the back, so the back edges of both sides can be removed, as can the top and bottom of the back itself.
F: The left and right sides of the shelves are hidden too.
G: Each of the back edges of the shelves is right up against the back, so they can be removed as well.

There's also ends on the left and right sides of the back which can be removed, and the outsides of the sides matched up so it doesn't have a hole.

Once all the unneeded polys have been removed, the count is down to an even 100 - saving 44 polys that weren't doing anything at all! 44 polys admittedly isn't that big a deal, but this same technique can be used on much more complex meshes and you can end up saving a lot more. Even if it's just a handful of polys per mesh, it's a good idea to take a look and see if there's poly underneath, buried in other parts, or up against other parts that can be deleted.

Alpha cutouts are your friends/use texturing for details:
Another mistake a lot of people make when modelling is attempting to shape everything out of polygons down to the last detail.

While sometimes this is necessary to get the effect you want, more often, it's easier to create the general shape and then use alpha cutouts to get the specific shape.

Here's an example, and one of the best examples of this in action: a flower.

This is just a quick and dirty example I put together to demonstrate the technique. If I were making this for real I'd spend more time shaping and working on it.

This is made out of three basic shapes. The cup of the flower is a sphere that I cut the top off of and then flattened a bit. The stem is made from a cylinder with a few stacks that I shaped, flaring at the top end to make the part that attaches to the flower. And the leaves are just planes with two divisions so I can make them bend a little bit. Depending on the size of the flower in-game, I could probably have gotten away with a bit less complexity in the cup of the flower, but you get the idea.

Now here's the same shape with the textures (again, pretty quick and dirty) that I made for it, but still with the wireframe overlay showing so you can see how the shapes correspond to the textured model:

You can see that even though the shape of the leaves as modelled is a bent rectangle, you can use alpha cutouts to make them into nice pointy leaf shapes. Same with the petals on the flower - though the flower is a solid cup shape, I can cut out the shape of petals exactly as I like.

And finally, the flower with no wireframe overlay, as it looks finished. Again, it's a little bit blocky but if this is going to be actual flower sized in-game, nobody's ever going to notice that the leaves and stem aren't perfectly smooth bends.

You will always look closer at your mesh and see more imperfections than anyone else ever will, so don't worry if the modelling isn't absolutely perfect when you zoom right in. Of course, you should make it look right, without any gaps or holes or anything like that, but if it's a little blocky when you've got your nose right up to it, that doesn't matter.

So what's the poly count for my flower? 208.

It's mainly so high because in order to make the flower part and leaves double-sided, I have to duplicate those parts and reverse the way the polygons are pointing. Polygons in The Sims 2 are one-sided, and in order to make something visible on both sides, you have to duplicate and flip it. So it's especially important that you keep your basic modelling low.

Just in case you were wondering, here's what my texture looks like for that flower. All of the grey and white checker areas are transparent.

You might also notice that because I didn't mesh each petal of the flower, not only does it keep my poly count down, but now I can change the type of flower quite easily just by changing the way I texture it. See?

Saving polys, and making a more versatile mesh - it's a win-win situation.

Here's another example of a good way to use alphas instead of polys. Let's say I want to make a wire mesh box. Now, I can use tiny little cylinders to make the wire mesh, but that's going to be very high poly, will take a long time for me to make, and won't be very versatile.

So instead, what I can do is make a box with solid sides out of planes, with edging made out of 4-slice cylinders. Like so:

And then, create a texture with an alpha cutout that will make the sides look like wire mesh... like this:

If I'd gone and actually made each wire piece, this mesh would be WAY high poly. But as it is, using just a box with plane sides and cylinders for the edging with a low number of slices, my poly count is very low. Even with the plane sides duplicated for double-sidedness, my poly count is a very reasonable and low - just 160 total.

Plus, if I wanted to do something different with the sides (like transparent coloured plastic, wood, whatever) I could do that too without having to use a different mesh!

The same basic principle applies even if you're not doing alpha cutouts. Even though you may have an idea of what your mesh will be used for, consider that other people may want to recolour your mesh in a different way - a couch they may want to use different patterns for the pillows, or make the seats and back a different colour than the base and sides. You may want to add certain details (like tufting on a cushion) which would be better done with texturing rather than actually meshing it in so that the cushion can be un-tufted if someone wants to recolour it like that. Think about other options for how your mesh might be used, and try to make it as versatile as possible.

Is this just for objects?
I know I've focused mostly on demonstrations that show this in use with objects, but this definitely isn't just for objects! The same basic techniques apply to all meshes for The Sims 2, and it's important to keep your poly count as low as possible no matter what you're making.

Just as some basic examples of how this applies to hair, clothes, and accesssories:
  • For hair, remember that you only need extra polys where you need to add extra detail - you'll need more polys in areas that bend, like around the neck and shoulders. Areas at the top of the head that are smooth, you can use less in those areas since they won't flex or bend much if at all.
  • Also remember to remove hidden polys - the inside of a hat that will never show doesn't need to be double-sided, and pieces of hair that you'll never see (like up underneath a layer) can be removed, too.
  • The same basic concept about stacks and slices applies to clothing and body meshes too - a round puffed sleeve made from a sphere probably doesn't need a ton of polys to look nice and round and smooth in-game... nor does a necklace made of individual beads need each bead to look perfect - they're so small, you're not going to notice if they're not exactly perfectly round due to reducing the number of stacks and slices. Even though an item may look a little less than perfect and a little bit blocky to you when making it, it'll look perfectly fine in-game. Compare your mesh to Maxis meshes and you'll see that theirs aren't super complex either.
  • Remember when making meshes to try to make them as versatile as possible. You don't need to mesh in individual buttons when those can be textured on. A small bow that wouldn't stand out much from the body can be textured on too rather than meshed. Tight sleeves on shirts or tight legs on pants don't have to be meshed in either. Not only does this reduce your poly count, but it lets people change your mesh to suit their needs, adding or removing the buttons, bow, sleeves, or legs as needed.

What if I've already made it too high poly or I want to convert an existing mesh to lower poly?
It's pretty common for beginners to model something up and then go, "Ack, how did my poly count get so high so fast?" A lot of beginners also think it will be easier to take an existing mesh from a free model site and use that instead of making their own. At this point, people start looking for automated poly reduction programs and utilities.

I recommend strongly against doing this. While these programs and utilities do exist, they are "dumb" utilities - they work on a specific algorithm which, while it can be somewhat useful, often results in a blocky, strange-looking mesh. You may get streaks of polys where it had been smooth, and rather unexpected and unpleasant results. It may be tempting to try anyway, and you can go ahead and see what happens, but you probably won't like the way it turns out. If you do auto-reduce, try doing it just a little bit at a time - don't try to bring it down all the way in one go.

It's usually better, though, to just re-model the parts that are too high poly if it's your own object... or recreate it from scratch yourself if it's not. If it's your own work, you probably don't have to do the whole thing over... just identify the worst parts and redo those. It may be a pain, but you'll get a better result and learn a lot more if bite the bullet and do it over.

In conclusion...
With any luck, this tiptorial has made you start thinking harder about your use of polygons, now realizing why it's so important to keep your poly count nice and low. Anything worth doing is worth doing well. Creating new meshes can be quite difficult, but if you learn to do it right and are committed to getting an excellent quality end result, it will all be worth the effort.

You are welcome to post on this tiptorial with helpful hints that I may have missed - substantial ones I may incorporate into the main document for others' benefit (with a thanks to you, of course).

You are also certainly welcome to post examples of meshes you need help reducing in poly count here. I and others will try to help you identify the specific areas that need work, and provide recommendations on how to reduce your poly count to a more reasonable level.


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#2 Old 13th Jul 2008 at 7:54 AM
Thanks for the tips! I may upload a couple of embarrassingly high-poly objects of mine at some point, but for right now, perhaps you can solve a small mystery for me: why is the poly count shown in Wings 3D so much lower than that for the same mesh in SimPE?
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#3 Old 13th Jul 2008 at 1:06 PM
Amber - Does Wings use quads (4 sided) or triangles (3 sided) for modelling? Several programs use quads so your count will double once you go put the mesh into SimPE.

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#4 Old 13th Jul 2008 at 7:52 PM
Originally Posted by HystericalParoxysm
Amber - Does Wings use quads (4 sided) or triangles (3 sided) for modelling? Several programs use quads so your count will double once you go put the mesh into SimPE.

Ooh, that would explain it! Wings allows for either. And here I thought I'd be saving some polys by quadrangulating some stuff. *Sighs* At least now I know...
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#5 Old 15th Nov 2008 at 9:08 PM Last edited by CatOfEvilGenius : 15th Nov 2008 at 9:15 PM.
*Excellent tutorial*, great examples. Wish this could be made mandatory reading. With a quiz at the end or you don't get to upload.

It would be nice if you could provide links to poly reduction programs though. I often find that I want to reduce stuff I've downloaded. If I can't, I end up not using it. I've been meaning to write a poly reducer for MilkShape for forever now, but if someone knows of one that exists, it might save me some work.

BENDY and CURVY stuff, use normals, not lots of polys
In the section where you discuss using minimal polys for bendy and curvy stuff, you can mention that a curvy appearance can be achieved with correct use of normal vectors. They can make something chunky look smooth and curvy (except for its silhouette). I made a MilkShape plugin, the normal smoother, that can be used specifically for this task.

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#6 Old 15th Nov 2008 at 11:57 PM
There's already a poly reducer built into Milkshape... but as I said in the tutorial, the issue is that ALL poly reducers are "dumb" tools and aren't going to do a very good job. It's way better to re-model parts that are too high poly, not use a tool to do it.

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#7 Old 16th Nov 2008 at 1:38 AM
Some poly reducers are dumber than others. I've seen some in the literature that do a great job on things like animal forms and human faces. The better ones preserve sharp creases if the feature angle is specified correctly. Yes, a human would do a better job. And when it comes to making your own meshes, you should redo it yourself. But I'm talking about stuff I downloaded, not made myself. I don't want to invest hours or days fixing up someone else's mesh.

People keep telling me MilkShape has a poly reducer, but I can't find it. If you don't want to post a link in this thread, could you please PM it to me?

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#8 Old 16th Nov 2008 at 1:47 AM
Well, it'd still be kinda hard for me to provide links to all sorts of programs to do it when A) I don't use them myself and B) I don't recommend them and also C) The point of this is to create your own meshes that are low poly, not reduce others' high poly meshes.

Milkshape's is under the Tools menu, DirectX Mesh Tools. Best done in small bits (drag it down like 1/4 the bar, reduce, check the mesh, repeat) rather than all at once. But still a very "dumb" tool.

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#9 Old 16th Nov 2008 at 2:03 AM
It's in Tools -> DirectX Mesh Tool. The problem is not that the automatic routines are bad in general, but rather that are bad for low-poly modeling. The DirectX Mesh Tool can probably produce a nice result reducing a mesh from 50,000 faces to 25,000; but reducing 2,000 faces to 1000 is *much* harder, and usually the result is ugly (often, the process creates holes and degenerated faces).

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#10 Old 16th Nov 2008 at 3:32 AM
thank you both

You're both right, this isn't something I would use when making a desk. If I was going to use a poly reducer for my own meshes, it would be on something with spline curve surfaces probably, like a bunny rabbit. Procedurally generated curved surfaces can sometimes be higher poly than is wanted or needed. Maybe that should be a separate thread? Lowering poly count in curved models? Maybe in a few months I'll get on that, when I get through my current project list.

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#11 Old 11th May 2009 at 3:28 PM
Default Thank you
Just wanted to say thank you for the great tutorial. I feel a little dumb, having missed it previously and looked for feedback on some stupidly high-poly things and then not having fully understood the advice I got about using alphas and how exactly one does that sort of thing and how it really won't matter in game.

Time to go rework all my projects ^^
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#12 Old 12th May 2009 at 8:41 AM
Ok, I've developed a question/problem related to this all, and I honestly have looked high and low in tutorial listings for the answer, but it eludes me, either because I'm just overlooking a tutorial that's right in my face or my search-fu is weak and I'm not entering the right keywords on the wiki:

To use alphas for fake texture, do the mesh-bits *have* to be flat planes, or can you, say, take an already formed cube (or other premade 3D shape) and repeat/mirror the alphas on all sides of that solid shape instead of joining individual planes?

I've made several meshes that have pretty flat, or only gently-curved main surfaces, and I want to make say, the front and back have see-through bits that match- but they have actual edges that I wish to remain solid... but maybe I just jumped to a bad conclusion planning things that way ^^;

And I have not been able to find the tutorial for how to actually make/use alpha channels either. I sort of hazarded a guess or two in SimPe, and exported alpha channels from textures, and then painted 'em up with the white-on-black (with grays etc) that I noted alphas seem to be- but then I became absolutely stumped as to how to integrate the suckers back in. I tried right-click importing the alpha channels into the texture pics, and it *seemed to work* in that the texture had transparency in all the right places and definitions, but when I committed it all and saved it, it reverted to awful pixelization of the texture with *no* transparencies anymore.

How far off the mark am I on what I've been doing? And *is* there a tutorial I have overlooked?

Sorry to be such a pest ^^
world renowned whogivesafuckologist
retired moderator
Original Poster
#13 Old 12th May 2009 at 8:55 AM
You can do alphas on any kind of shape you like. Complex alphas are present in all manner of items in the game - the stranded effect on hairs, and the individual leaves on trees are both good examples. You can repeat the textures however you like - same texture on all sides of a cube, one texture on one side and all the rest the same, whatever. Just depends on how you lay out the shape, how you map it, and how you do the texturing. You can get real creative.

Only thing to bear in mind with non-flat shapes that will overlap visually in the game (like front and back of a cube) is the material definition settings. I don't want to get too complicated here, but unless it's just a single flat plane (say, a tabletop) then in the material definition (TXMT) you'll want stdMatAlphaBlendMode set to "none" rather than "blend" or it'll do this weird overlapping funky thing in-game. Unless you have a specific reason for using "blend", always have it set to "none" and you should be fine.

Now, as for front and back alpha with solid, non-alpha'd, meshed-out edges (I'm assuming you mean your wall sculptures), that's -possible- but it's going to be an almighty pain in the ass to get working right. Your best bet in that kind of situation would be to basically have the front and back stick out just a smidgen from the edges, so that the edges are all a little bit recessed. Matching up the edging exactly would be really difficult, and due to the way mipmapping (smaller images that display at further-out zoom levels) works, even if you match it perfectly it might display some gaps when you zoom out.

Doing alphas in SimPE is actually pretty easy. Try exporting a texture that already has alpha transparency as a PNG file and looking at that in your graphics program of choice. You'll see it has one layer with the transparency built in. No fussing with separate black and white images (as you've seen, that screws up your texture and works poorly), you just use Build DXT and bring in your texture at DXT3 or DXT5 (those use transparency, DXT1 doesn't).

My recommendation (take it or leave it, I don't mind) with those sculptures would be A) either make them completely flat as a wall decal, like a sticker, using Pixelhate's wall overlays, and don't bother with 3Dness for them at all, since they are already quite flat and the difference in appearance in-game will be negligible or B) Take the 4000-ish poly version that you last had, make it thicker so it's more 3D and less flat, and make it a large free-standing floor sculpture, similar to the big modern sculpture that looks kind of like funky wind chimes. 4000 polys for something like that would be kinda high, but not insane for the size and overall decorating "impact" it would give at that size.

my simblr (sometimes nsfw)

“Dude, suckin’ at something is the first step to being sorta good at something.”
Panquecas, panquecas e mais panquecas.
Field Researcher
#14 Old 12th May 2009 at 9:10 AM

What I've done so far is for the wall hangings, yes, those are what I turned into more flat objects and am hoping to use alphas to get the texturing right for them- that one that I posted earlier is now down to about a total of 1000 polys- still not a PERFECT count, but sooo much better than 4K. I'll tweak it some more so the edges overlap like you suggested either later tonight or tomorrow, and try out the other suggestions too on various test meshes.

I'm just a little too set on wanting them to actually be at least a little 3D to turn them into decals, both out of sheer ornery "Well they're sorta 3D in real life" and also because if nothing else, I'm sure learning how to use Blender doing it this way. LOL

And there will be free-standing sculptures in the mix later too.... I've yet to be able to really make one in RL due to cost and equipment issues, but hey, in Sims I don't have to rent stuff or hire other craftsmen for welding and steel cutting, so darned if I'm not gonna go wild.
world renowned whogivesafuckologist
retired moderator
Original Poster
#15 Old 12th May 2009 at 9:11 AM
Hey, fair enough. They're cool however you end up doing it.

my simblr (sometimes nsfw)

“Dude, suckin’ at something is the first step to being sorta good at something.”
Panquecas, panquecas e mais panquecas.
Field Researcher
#16 Old 12th May 2009 at 11:18 PM
Default Still not getting it, sadly...
Ok, I'm still not doing something right. In SimPE, the 'preview' image looks *almost* right. It is hideously pixelated and rough, however. In game, well, the current 'slapdash' textures I did just to test things out for tweaking are still horribly mutilated/pixelated, and there's no sign whatsoever of the sections that should be invisible- the objects look *almost exactly* like they looked before I added any alpha to the textures. I did make sure to save 'em in build 5 format, as well.

Could this be because I reset the texture default mipmap for the table from 256x512 to 512x512 so I'd have more room to figure out my texturing, or because I choose poorly in the UV mapping department? I *think* I got the proper material definition in- I set it to 0 which I was guessing meant 'none' from other fields and tutorial references... (And for kicks I poked at the reflectivity in my latest try too, but even without having set the reflectivity values away from 0 I was having the same issues.)

For UV mapping I had followed the basic 'Making objects in Blender' tutorial and used UVMapper- I don't think I used planar though when I made the map for the 'body' object, because no matter how I set the planar fields, it looked like it'd be heck to texture over them- they'd only show the edges, or have the face angled so that I'd have to warp the surface images... so that might have been my mistake as well. (I didn't see specific instructions to NEVER use any other form of UV map, and some of the other textures I've seen from Maxis objects I've disassembled looked like they were more 'box' than planar, so I thought maybe it'd work ^^; )

I'm going to toss in some screenshots from SimPE and the game to show my mat definitions and what I mean about how it looks in preview and game mode.
#17 Old 13th May 2009 at 2:44 AM
Just for the record, I learned by trial and error that it *is* possible to do the texture and alpha separately, if for some reason you really need to. What you have to do is import the new texture, then import the alpha without committing. Then export and re-import the texture, and the alpha will "take" and not create the usual pixellation nightmare.

This process does however degrade the image slightly each time you do it, so for best results keep a separate copy of the texture, open the file in your image editor (after going through the process above, the copy on the disk should now have the correct alpha included) and paste the full-quality texture in, save and re-import.
Test Subject
#18 Old 20th Jun 2010 at 1:25 AM
I am so blown away! This is the best set of tipts (Tiptorial) I have came by. Thank you very much. Even though I can't get past trying to get the meshes in my game, at least I will have some cool meshes for when I finally figure it out.
#19 Old 4th Oct 2010 at 6:46 PM
I was sent to this tutorial by the Upload Manager, and it is EXACTLY what I was looking for. Thank you HP for taking the time out to do this tutorial. It was very easy to follow. You rock!

Please consider taking part in LifesLover's "The Build To Plan" Contest. You'll make new friends and have tons of fun!
Lab Assistant
#20 Old 25th Feb 2011 at 1:51 PM
This Tutorial is highly useful, informative and easy to understand and I would REALLY REALLY like to keep it handy at all times. So why can't I get it as a PDF-File or something similar? Sadly, this is a problem I've came across all over your website. The option "Show printable version" mostly reduces the thread to plain text without the pictures which makes them quite useless, sofar I've only found very few cases in which I could actually use that version to save the tutorial. The wiki-link only links back to this thread, it doesn't link to an actual wiki-article (that's a perpetual nuisance I've came across and VERY annoying!). Could you please, please, pretty-please attach a file?
HystericalParoxysm - many thanks for ALL of your articles. They're really easy to understand and I appreciate the effort you put into them and this reply is in NO way a critism of your tutorial!
Site Helper
#21 Old 25th Feb 2011 at 4:25 PM
Originally Posted by MosconeCtr
The option "Show printable version" mostly reduces the thread to plain text without the pictures which makes them quite useless, sofar I've only found very few cases in which I could actually use that version to save the tutorial.
This is a fairly recent change to the website; you used to be able to get a printable version with pictures. Perhaps you should bring up your concern in the Site Questions and Issues forum (under the Site menu).
Lab Assistant
#22 Old 26th Feb 2011 at 11:45 AM
Thanks Mootilda, I'll do that.
Guess I'll have to wait for the admins to decide if they want to change this issue until I'll get a printable version of this tutorial then...
Forum Resident
#23 Old 17th Sep 2011 at 10:16 AM
Thanks for this informative tutorial. My head is spinning so much info,I garra read it a bit at a time. Very true what you're saying.Keep up the good work.
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