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So I am reading an image from a png file into a 2D sprite. This sprite serves as a "province" in my game. Currently, I am getting this:

enter image description here

If you look closely, you will notice that you are seeing the square corners of each pixel, because I am mapping the image on a 1:1 ratio of pixels:world coordinates.

What I want is a slightly rounded corner in these places. Look at the 2-dimensional provinces in this example:

enter image description here

I have been googling around for algorithms, but most answers simply say "use a shader" and don't describe the techniques used to do this (until now I have not done much with shaders). If you would like to see my working code for the province system, it is posted on my answer to my own question here.

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    \$\begingroup\$ I might be misinterpreting or missing something obvious - but isn't that just a higher resolution picture with more detail? \$\endgroup\$ – Charanor Feb 10 '17 at 0:08
  • \$\begingroup\$ @Charanor The map image I am loading is already 8000x4000 (or around that size, anyway). To achieve the resolution I would need to load insanely large textures into memory (and since I am targeting some of the higher end Android tablets, there is a limit to what I am able to do). For a comparison, Paradox loads their maps from much smaller textures, and use custom shaders (in their own shader language with built-in functions) to make most of their cool effects happen. \$\endgroup\$ – JDSweetBeat Feb 10 '17 at 14:08
  • \$\begingroup\$ But just because it's larger doesn't mean that it automatically has more detail. If you want jagged / smooth non-square edges surely you just make it in your image editing software? Why make a shader that's probably slow and has to do extra work? You will always have to have large textures for a large scale 2D map, unless your map is constructed using vector graphics or a 3D mesh (Like Total War, for example). \$\endgroup\$ – Charanor Feb 10 '17 at 14:29
  • \$\begingroup\$ @Charanor Each province is about 100-300 pixels in total. I map each pixel to 1 world coordinate. I am unsure about how to make a more detailed textures without more pixels as the lowest "unit" of editing in gimp is a pixel... \$\endgroup\$ – JDSweetBeat Feb 10 '17 at 15:08
  • \$\begingroup\$ Now that's a whole other question. You should (almost) never use 1:1 relationship between pixels and world units. You should look into viewports and how to change the size of the unity viewport. \$\endgroup\$ – Charanor Feb 10 '17 at 15:20
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One economical way is to perform tile-based rendering, but have lots of variations in tiles depending on the edge type (straight edge, inner corner, outer corner etc.) Here's an example:

Land Tileset

Note that despite the appearance of a very complex coastline, you can pick out variations of coast types, where each variation within a type are interchangeable. For example, here are all the variants where the coast goes from the top-left corner to the bottom-left corner, with the land on the upper diagonal:

variants

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  • \$\begingroup\$ man I wish I'd seen this tileset image a month ago, that would've been so useful for a project I'm working on! \$\endgroup\$ – jhocking Apr 28 '17 at 14:35

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