Introduction

In this tutorial, we are going to cover a little trick for warping a square texture into a mostly seamless circular texture. As always, we will be using our favorite free image editor, GIMP, along with our favorite free filter and effects library, G’MIC. These circular textures are used for special purposes, such as the construction of tile-sets. For instance, you can create the tops of columns or tables, textures for roofing, circular flooring designs, shields or wall decorations, round carpets, and more!

Polar Warping

While this tutorial is incredibly simple, the resulting circular textures are incredibly useful! To begin with, we want to select a texture that is already seamless. This is not necessarily a requirement, but for the sake of this tutorial, and to keep things looking nice and neat, we will start with a seamless texture.

Seamless Brick Texture

Now we need to launch G’MIC by going to Filters -> G’MIC Qt. Here you will see a massive list of filters and effects, but the one we want to use here is called Kaleidoscope [Reptorian-Polar] When it first loads up, you can already see the result is pretty close to what we want!

Kaleidosope [Reptorian-Polar]

There are only a few settings that we need to change in order to make our texture look correct. Make sure that Angle Edge Behavior and Radial Edge Behavior are both set to Repeat. This makes it so the texture repeats as the texture approaches or extends beyond the edges of the canvas. For the very last step, we need to set the Angle Cut to 4 and the Radius Cut to 1. With all these settings in place, the texture no longer distorts or stretches around the edges.

Angle Cut – 4 / Radial Cut – 1

Press Apply to process your texture with the current filter settings, and then press OK to close the G’MIC window to see the filter applied to the original texture.

Completed Circular Texture

The resulting circular texture is also mostly seamless, but not entirely without flaws depending on the texture you use. As you can see in the image below, if you tile the image, the edges do still remain seamless even after applying the radial filter, though there may be some pixels that are not perfectly aligned. Unfortunately, there is no way to avoid this, but this can be easily remedied using the clone tool and some manual editing. 

Tiling the Texture Along Both Axes

The Radial Cut setting determines how many times the texture repeats along the Y-Axis, while the Angle Cut setting increases the number of angular slices around the center point. Increasing these values will produce a smaller version of the texture, which can be useful for making variations. For instance, doubling the values of the Angle Cut and Radial Cut settings will double the amount of bricks displayed in the final texture.

Settings Doubled – Angle Cut 8, Radius Cut 2

The opposite is true if you divide those same values by 1/2 to get a larger variation of the texture. This can be useful with certain patterned textures, such as bricks or tiles, and can sometimes produce shapes that resemble flowers or fractals. In most cases, it will produce a simpler version of the texture you are warping, which can also be very useful. You may also want to try messing with the Conical Start at 0 checkbox, as this can produce multiple variations of the texture as well by rotating the starting angle of the texture.

Settings Divided by 1/2 – Angle Cut 2, Radius Cut 0.5

Try starting with different types of textures to get all kinds of different results, like fancy patterned floor tiles or circular fractals. Sometimes the results can be quite pleasant or surprising, so feel free to experiment!

Circular Texture Examples

There is one last little trick for making more variations, and that is creating a truly circular texture instead of a square one. Simply change the Radial Edge Behavior setting to None, and the resulting texture will be circular instead of repeating or tiling off the edges of the canvas. This trick is very useful for making textures for circular roofing or domes.

Radial Edge Behavior – None

As a final step, you can use the cartesian transform and cropping methods described in the Isometric Textures Tutorial to convert the circular texture into an Isometric Tile to be used as a floor texture, or to be further cropped into isometric objects.

Isometric Tile Made with Cartesian Transform

That’s all there is to it! Now you can save or export your new circular texture or create more of your own. Don’t forget, you can also grab a whole pack of pre-made circular textures in the Circular Texture Pack from Screaming Brain Studios to save yourself some time!