woeful cloud
In woodworking, a miter joint is a way to join 2 boards (of the same width) at any angle such that the edges are flush. This same technique can be applied in Blockbench in order to create seamless transitions between differently angled pixel grids. As they say, a picture is worth a thousand words, so a more clear understanding of what is meant should be clear from these images:
This guide will be split into 3 sections, in ascending complexity.
In order to create a miter joint, start by creating a series of connected faces. Here is an example:
woeful cloud
Select all of the faces, and extrude. On the extrusion menu, make sure that direction is outwards and that even extend is checked. (If you are using an older version of BB this menu may not have the required settings).
Adjust the extend value (it can be positive or negative) to your liking; just make sure that the extruded sides don't extend past one another, (which will likely be more common with sharp angles and/or shorter faces. It's possible to address this, but is more complicated and will be discussed in the third section of this guide.
Some examples of possible extrusions
An example of an improper extrusion. In this case a smaller 'extend' value needs to be used to avoid the overlapping.
woeful cloud
Optional:
It is also worth noting it's possible to extrude on both ends, rather than in just 1 direction. To do this, before extruding any sides:
If you wish to clean up geometry:
If needed, cover any holes with new faces. This can either be done preliminarily by duplicating the original mesh, or by simply selecting opposing lines and creating new faces. Repeat this process until the faces have been replaced
Now that we have the mesh set up, we can begin texturing and fixing any UV issues. In this case I will generate a mesh. Notably, I will disable island entirely because it will generally simplify this particular workflow.
Depending on your needs this might be good enough. If you wish to make sure the edges are seamless, you may need to make small adjustments to the UV scaling/positioning. For example here are some things I would personally try to fix:
Edge not aligned with pixel grid, vs. aligned:
grid around corner improperly scaled/ aligned vs. fixed:
(In the future I might make a guide focused on editing UV maps but that's a large topic, so I won't cover it here)
Now that we've gone over the basics of miter joints, we can apply the same idea to closed-loop polygons.
This can be used on complicated polygons like so:
Or on flat faces on more complex 3D objects. For example here's a comparison between using a single face vs. a miter inset on the sides:
It's important to keep in mind that the surface must be flat (or extremely close to being flat). Otherwise the outcome mesh will not look very good. Notice the squad shown here is not flat. Applying the technique I will detail here will lead to it looking like so, which is likely not what you want
With that out of the way, let's move onto the actual technique.
Start with the flat polygon. This could be created on the spot for this, or it could be part of existing geometry. In this guide I will be following the latter example.
Once you have the polygon, extrude it. The amount you extrude it doesn't really matter, as this is only temporarily needed for the technique.
Delete the face that was just extruded, so all you are left with are the 'walls' surrounding its perimeter
Select the 'walls', and extrude again. Make sure even extend is enabled. Adjust the extend value, but the value will need to be negative (unless your mesh is inverted). I'd recommend setting the value to an integer, such as -5 in this example
Like mentioned in the miter joint section, problem will arise if this value is too large. For example there is overlapping geometry in this example if I set it to -8. This will be addressed in the final section of this guide. For now, just pick a value that isn't too large so that this issue does not arise
Once you have the 'margin' of the polygon set, select the outmost surfaces (along with the walls which should still be selected, and delete them
Create new faces over the hole
Repeat this process for any faces which require a miter inset. For the same reasons described in the miter joint section, it's likely worth generating the texture with the islands disabled. This makes it more likely for each of the margins to already be oriented in the proper rotation/alignment. Another option is to use the seam tool.