Thank you! ⭐

[hermanschaaf]

I discovered these tutorials quite by accident through the Ebiten website, and just wanted to say thank you! They're really well-written and I greatly enjoyed going through them and learning about Kage and shaders in general.

The only bit of feedback I'd like to give is that I'm still not sure what the second parameter in Fragment (vec2) is for; it doesn't seem to be covered in the intro tutorials. I see on the Ebitengine page that it's called texCoord, but not sure what that means - still experimenting to try and figure it out :)

[tinne26]

(Oops, I forgot to enable discussions on this repository...)

Yeah, well, it's a tricky thing to explain properly. The short version is that under the hood, everything are triangles, and when drawing shaders, triangle vertex coordinates and triangle texture coordinates are different sets of values. This texCoord argument gives you the texture coordinates for the current fragment to be used with imageSrcNAt(pos vec2), but it doesn't work in many cases, which is why I avoid it in the tutorial. Hajime is also likely to change some of this stuff in the future to use pixels instead of texels anyway.

There are two documents that give the full context and actually explain all this in detail, but they are long.

• Understanding the mapping of textures to triangles: https://github.com/tinne26/kage-desk/blob/main/docs/tutorials/triangles.md
• Understanding texels and why sometimes texCoord doesn't work: https://github.com/tinne26/kage-desk/blob/main/docs/tutorials/texels.md