A few months ago, I reviewed Substance Designer by Allegorithmic. This time, I will be taking a look at Substance Painter, by the same company. Substance Painter is a 3d painting and material creation tool. If you've used applications like Mudbox (for texture painting), Mari, or BodyPaint , then you can get a pretty good idea of what kind of tool Substance Painter is (by the way, I've written reviews for various Mudbox releases, and one for Mari in the past, so you may want to check them out).
As I said before, Substance Painter is a 3d painting tool that lets you paint your materials directly on top of your objects. The workflow in SP is similar to Photoshop, as you can have layers on top of each other, group layers and add effects. One of the cool features of Substance Painter is that, as the name implies, you're not just painting textures; you're painting actual materials onto your model (however, you can't export substance files, only textures, as I will explain soon).
If you've used Mudbox before, you know you can export displacement and vector displacement maps. This is a feature Substance Painter lacks. Unlike Mudbox, Substance Painter is used only for painting, not sculpting, so you can't generate maps that affect or modify your geometry's tessellation in any way.
Since pretty much all modern engines support PB-rendering, this means SP offers a "what you see is what you get" workflow, as the material painted in Substance Painter, will look virtually identical to that inside your game engine. However, unlike Substance Designer, Substance Painter does not export substance files, but single texture files that can be used in your application of choice. If you have Substance Designer, you can easily import those textures into a new project to create your own substance, maybe make more adjustments to it, and then export it as a substance file. Personally, I like to work with substance files rather than separate textures, because I've realized that substance files are better at keeping the overall look of the material while separate texture files will often yield a slightly different look.
When you start painting your material, you can decide which channels will be painted (diffuse, metallic, roughness, and so on). You can toggle those channels on and off, in case you want to focus on some specific channel (or in case you want to paint everything but a specific channel). You also have the ability to paint from the material presets and toggle the channels in those.
Just like in Mudbox, you can opt to use different brush shapes, and also use a stencil overlaid on top of your view, to modify the way you paint. Brush shapes work just like in Photoshop, allowing you to change your brush strokes to get different effects. Stencils are grayscale images overlaid on top of your view and are used to modify or project those images on top of your model.
If you've used Substance Designer, you should be familiar with the texture baking features. Baked textures in Substance Painter (and Substance Designer) can be used to either act as normal maps (generated with a high and low-resolution mesh), ambient occlusion maps, or special maps that serve to specific purposes (like a curvature map). For example, after baking these maps you can use the tri-planar projection (also available in Substance Designer) to improve texture projection and get rid of seams in your textures. This is very useful when using procedurally-generated textures (like noise or grunge maps) since these maps can cause horrible seams along your UV edges, but tri-planar projection lets you get rid of those seams and create a smooth transition. Obviously, since Substance Painter is a 3d painting tool, you can get rid of those seams yourself by painting on top of the model (that's what I do in Mudbox), but tri-planar projection saves you time by solving that issue for you.
Substance Painter also offers smart materials. Smart materials are material presets that store layer effects and map linking information. The linked maps I mention are actually the ones you can bake directly inside Substance Designer. This is a nice feature that makes all of your substances reusable, because you can apply them to any object, regardless of the UV layout or model topology. But, keep in mind you will still need custom maps, like the curvature map or normal map, so you still need to bake the maps for the model before you use those smart materials!
If you've used 3d paint applications like BodyPaint or Mudbox before, you will have no problems getting used to Substance Painter. For game development, Substance Painter (combined with Substance Designer) can be a great addition to your toolset. On the other hand, remember Substance Painter doesn't support displacement or vector displacement map generation, so if you work with media production or visual effects, you'll still need a sculpting application to make those.