Here is my low poly game character animation test in Blender.

I made this video about possible issues with concave polygons in 3D modeling.

Concave Polygons in 3D Modeling

I had this issue with a knife model that I made before for games. One of the quads was kind of shaped like triangle and I didn’t notice. The model itself was pretty well optimised, there was no ngons whatsoever, and all was well. But this one anarchist poly just kept flipping about in 3Ds Max.

concave polygons in 3d modeling

Convex and concave (non-convex) polygons and a quad shaped like tri.

Now I know there are those who know much more about geometry in mathematics than me and I’m quite sure I will get some serious feedback. However, what my question really is is this; if you imagine a quad that is shaped like triangle, that one of the sides is actually two sides that share the same angle, is this convex or concave? Especially I’m interested about this from the perspective of a 3D modelling application. Max seems to think about this differently than other apps.

Now, it’s possible to use concave polygons even in final render. I have sometimes used it and even the letters in the flat 3D plane text that’s visible in the video is basically just that. (and the question mark has this actual issue!) But having extreme concave polygons can be a huge pain to deal with in render time.

None of this really matters if you are dealing with subD cage mesh, those meshes can and will get pretty wild and that’s just, well normal, anyway the mesh is subdivided and it’s nothing but a cage mesh after all. And as William Vaughan described in his wonderful tutorial series, four sided triangle can be a great way to optimise sub-D meshes.

concave polygons in 3D modeling

Quad that is shaped like a tri. Is this convex or non-convex polygon?

However it’s best to avoid non-convex polygons in traditional meshes.

Please see also my guide to non-manifold geometry and a ways to fix it.

Introduction to 3D Coat PBR texturing

Here is a short 3D coat PBR texturing tutorial on how to use smart materials (available in 3D Coat 4.5) and quickly create a realistic physically based textures. Smart Materials are excellent way to preview different material properties in real time within 3D Coat, and new Smart Materials can be also created from scratch.

What I especially love is the 3D Coat’s ability to create ambient occlusion and curvature maps. In some cases baking in xNormal is not necessary at all. Smart Materials can then take advantage of these maps to create different effects such as edge wear or dirt accumulation in occluded places. Tweaking Smart Materials on the fly is also easy due to the built in tools, so we can always precisely set the scale of scratches and such.

I didn’t mention about it in the video but 3D Coat smart materials do cube mapping, which is kind of like Substance Designer’s tri-planar projection with a less fancy name, so no worries about those UV seams folks, they won’t show up. 🙂 Good times.

A good alternative

3D Coat is a solid alternative for more expensive programs such as zBrush. It is possible to create entire models from scratch within 3D coat nowadays. Topology tools as well as UV tools have always been a favourite feature of mine in 3D coat, but these days I am creating entire models from scratch within the application, starting from sculpting all the way to the retopology and UV mapping, and now, texturing too. There are some features that even rival zBrush such as per-pixel painting. At this price point, 3D Coat is such attractive alternative indeed.

What’s also great is the support for T-Mikk tangent basis calculation, making this fully compatible with xNormal maps and like.

I will be creating many more 3D Coat tutorials soon. Please subscribe to my channel by all means.

Please check out my 3D Coat PBR texturing video below.


3D modelling and (everything 3D for that part) used to be an arena owned by gurus. I remember when I first started playing with 3D in Povray back in 1996. I learned Bryce and completely enjoyed making landscapes with it, but it didn’t allow any kind of real 3D modelling.

Polygonal 3D modelling tools were scarce and expensive. Getting into 3D modelling was hard simply because the cost of the software was prohibitive.

Let’s zoom into 2016.

Aalto Votive in Lightwave © Jaakko Saari
Aalto Votive rendered in Lightwave © Jaakko Saari

Getting into 3D modelling for free (and reasonable cost options)

The world has changed some, to say the least. We’ve got free application Blender. SketchUp Make (free for non-commercial use). Sculptris. Windows 10 comes with free copy of 3D Builder. And for 99 dollars you can get amateur version of 3D Coat, a sculpting and 3D painting program that rivals even the zBrush (the professional grade sculpting program that’s used to make movie models. Amateur has some limitations but not severe ones). Even professional level applications which allow animations, particle effects, bone deformations and so, such as Newtek’s Lightwave are no longer crazy expensive.  Even Autodesk has a new pay-as-you go model, for less than 200 dollars per month you can get the best of the best.

Getting into 3D modelling and animation with Sketchup
SketchUp Make is free for personal use.

Definitely the cost can no longer be an excuse of not getting into 3D modelling. If you are passionate about it but can’t afford a software, just download the free version and go from there.

But the cost is not the only thing that has changed. I would argue that the tools are also way better and easy to use than they have ever been. Sketchup Make for example has a very low learning curve. You don’t necessarily need to know about ngons or polygons in order to use it. It helps if you do know the basic theory of polygonal shapes but you start to create 3D shapes even with zero knowledge.

For digital painters for example, the ability to build simple 3D buildings can help to achieve a good perspective. You can for example render out a simple scene and then paint on top the 3D construct..

Getting into 3D modelling and animation with Lightwave
Recent version of Lightwave is no longer so expensive, but it has never had such a strong potential.

Recommended 3D software production

If you are on a budget and need to create models for animation or TV production, I would recommend Newtek’s Lightwave. It has everything that a full blown 3D animation production would require, comprehensive 3D modelling tools, physics effects (that finally work now that we got Bullet Dynamics), node based materials, bone deformations and it works fully in Linear colour space. The latest version (2015 as of writing) costs $695 at the moment which is a bargain. Only thing that Lightwave doesn’t really have at the moment are the sculpting features and built in PBR support.

Getting into 3D modelling and sculpting with Sketchup
Spaceship modelled in 3D coat’s voxel sculpting room.

If you need sculpting I would recommend either Pilgway’s 3D Coat or Pixologic zBrush. I have commercial licenses for both and I love them both in their own ways. 3D coat has excellent UV unwrapping, pixel painting and retopology tools, and their voxel based sculpting truly rivals the bigger brother although the tools might not be refined to the extreme the same way as zBrush is. 3D coat is also somewhat often updated  and their support is fast.

zBrush 4 has not seen update since 4R7 P3 and it’s been a while, but the latest release continues to be the ultimate and arguably the best 3D sculpting application this planet has. It’s weird app to use (in a good way) as it’s kind of designed for artists and those who have studied sculpting academically. For example 3D models are called tools for some reason, and so on. Pixologic is preparing a new application, zBrushCore which they are going to release later this month in zBrush Summit which according to them is “streamlined version of zBrush”.

zBrush prop modeling
a prop being modelled using zBrush sculpting tools

If you have curiosity towards 3D modelling and graphics but haven’t had the courage to try, by all means do try. You can download free trial of even some of the pro tools and give them a go.

Updated September 22, 2016: I forgot to mention 3D Builder!

Check out the tutorial using 3D coat primitives: