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Show HN: Krita RGBA Tech – Bringing Realistic Metal to Life in Open-Source Art

271 points by draneria 2y ago

Krita's v4.2+ RGBA brushtips let you paint with dimensionality, and it's a technology that Photoshop doesn't have (≖‿ゝ≖) It lets the creator do things like emulating light direction, making brushstrokes look 3D. I used them to make a set of metallic brushes. If there are any FOSS artists around, feel free to test them out. (p.s. Yes, I am learning Github so I probably made repository mistakes - apologies in advance lol)

solfleur 2y ago
It's always amazing to see what neat brushes are out there; being able to interface with a practically limitless assortment of different artistic mediums through a single universal method (simple and intuitive, no less) never ceases to amaze me. Kudos! I'll definitely give it a try!
- draneria 2y ago
  Thank you! Last year there was a special breakthrough for Krita, because a contributor called Memileo figured out a way to bake light into the brushes using Blender. They made a beautiful Impasto set (https://krita-artists.org/t/rotating-light-brushtips-wip/64930 https://krita-artists.org/t/rotating-light-brushtips-wip/649...), their work was a huge help for my own brushes :)
  - itishappy 2y ago
    Memileo's results and your own are both incredible. Wow. How baked in is the light position? I'd imagine it's possible to rotate the light in editor but not change it's height (without some work in Blender).
    - draneria 2y ago
      Ah, you would need to ask them for a concrete answer, but my understanding is that it is completely baked in. Long optional explanation: I say that because I think Memileo sculpted the actual brushstroke in Blender (https://krita-artists.org/uploads/default/original/3X/5/7/57dde917c9a0b53f34894b147e4b431c084e1c0f.png https://krita-artists.org/uploads/default/original/3X/5/7/57...) and rendered lighting at different angles, and exported each as an image. Each rendered image becomes 1 frame of the "animated brushtip", with the option that each frame matches "direction" rather then being "incremental", and thats how you get the faux-light! The cool thing is that you can extract and edit the animated brushtip in Krita e.g. this one "https://github.com/Draneria/Metallics-by-Draneria_Krita-Brushes/blob/main/brushes/memileo_360light-PHOTO-A_06-incremental.gih https://github.com/Draneria/Metallics-by-Draneria_Krita-Brus..." Which means theoretically, you could use photo editing to change the height I think!
      - itishappy 2y ago
        Coolest thing I've seen all day. Thanks!
      - stuaxo 2y ago
        Great stuff, it's good to hear how brushes work in these programs, reminds me of a great chat with one of the MyPaint devs.
retSava 2y ago
Thanks for sharing! These look amazing and I look forward to trying them out.
getToTheChopin 2y ago
Lovely textures, thank you for sharing. Will try them out in some generative art projects I'm working on!
metallicss 2y ago
Great work! I have been looking for an excuse to try out Krita. This just might be it. Shameless plug: I am also a sucker for metallic aesthetics, and I made this FOSS library to enable realistic metal textures on the web (for buttons, cards, input elements, etc.): https://www.metallicss.com https://www.metallicss.com
- esperent 2y ago
  Very nice, I approve of anything that goes against the Material Design hegemony. One question though: there's a (relatively) large delay updating the demo when I change the convexity. Is this something that comes from the update script or is the effect itself slow? Because I don't think I've ever seen a CSS effect that takes a half second to update before.
  - jraph 2y ago
    There are a lot of canvas in there, I doubt CSS is involved much in drawing this effect.
    - esperent 2y ago
      I checked out the source, there's only a single canvas being used to render a base64 PNG. The PNG is just a 400x400 spherical reflection map, which is basically a required component of any metallic effect. I don't think that would cause a slowdown.
- mattkevan 2y ago
  Very cool! It'd be fun to use the webcam to create live reflections.
- draneria 2y ago
  wow, that's amazing! I'm gobsmacked you can make something like this with CSS, that is so cool
  - kroltan 2y ago
Aeolun 2y ago
Honestly, I’m most impressed by that fantastic demo gif.
atmanactive 2y ago
Just a small favor please: in your README.md file, on the first mention of word Krita, make a link to Krita repository or website. Thanks.
- draneria 2y ago
  Added! Thank you for pointing that out (´｡• ᵕ •｡`)
Llamamoe 2y ago
So what does it do? Create a normal map while drawing?
- draneria 2y ago
  On the right track but not quite! Every brush in art software uses an image (raster or auto-generated) to paint with, called a "brushtip". Usually, the brushtip only gives information about which bits are opaque, and which arent - the shape! However in Krita, theres another dimension you can define; value, or lightness. So there's nothing being generated or created while drawing, its just that some very smart people have coded Krita for the "brushtips" to do more as a baseline. Not every software works exactly the same ofcourse! This is just my beginner level understanding of it all, I hope that helps
  - short_sells_poo 2y ago
    Photoshop and other painting software had "intelligent" brushes for a while now. These try to simulate stuff like paint mixing (even watercolor), opacity and texture.
    - draneria 2y ago
      Could you give me an example? I'd love to know more about the watercolour paint mixing. If you meant the "live tip" settings of Photoshop, you can do all that in Krita too, using the "texture", and "mask tip" features. RGBA seems to definitely be something Krita has over Photoshop, but I could well be wrong! by the way, there are other softwares like Rebelle that try to truly simulate traditional mediums - bordering on a whole-ass physics engine that works completely different in the backend from PSD/Krita. Unfortunately its a paid software so yeah :s
      - short_sells_poo 2y ago
        It's been a while, but a bit of googling turned up this: https://www.adobe.com/uk/learn/fresco/web/realistic-watercolor-painting https://www.adobe.com/uk/learn/fresco/web/realistic-watercol...
jeremyscanvic 2y ago
That's cool! Great work!
bloopernova 2y ago
This is fantastic, the paint looks great, excellent job :)
isodev 2y ago
Krita is fantastic, and these look gorgeous! Thank you so much for your work.
lttlrck 2y ago
Amazing. This motivates me to try Krita. Well done.
michael0x11 2y ago
Pretty neat tech - the RGBA brush engine in Krita is doing something fundamentally different from PS's basic alpha masks. Being able to encode directional data in the brush tip itself opens up some interesting rendering possibilities. Been messing with similar effects in PS using layer styles but this seems way more efficient.
- draneria 2y ago
  Exactly! it is really incredible. I've not used Photoshop much, I'd be curious to know how the two face-off in the realm of brush features haha

271 points by draneria 2y ago

solfleur 2y ago

It's always amazing to see what neat brushes are out there; being able to interface with a practically limitless assortment of different artistic mediums through a single universal method (simple and intuitive, no less) never ceases to amaze me. Kudos! I'll definitely give it a try!

draneria 2y ago
Thank you! Last year there was a special breakthrough for Krita, because a contributor called Memileo figured out a way to bake light into the brushes using Blender. They made a beautiful Impasto set (https://krita-artists.org/t/rotating-light-brushtips-wip/64930 https://krita-artists.org/t/rotating-light-brushtips-wip/649...), their work was a huge help for my own brushes :)
- itishappy 2y ago
  Memileo's results and your own are both incredible. Wow. How baked in is the light position? I'd imagine it's possible to rotate the light in editor but not change it's height (without some work in Blender).
  - draneria 2y ago
    Ah, you would need to ask them for a concrete answer, but my understanding is that it is completely baked in. Long optional explanation: I say that because I think Memileo sculpted the actual brushstroke in Blender (https://krita-artists.org/uploads/default/original/3X/5/7/57dde917c9a0b53f34894b147e4b431c084e1c0f.png https://krita-artists.org/uploads/default/original/3X/5/7/57...) and rendered lighting at different angles, and exported each as an image. Each rendered image becomes 1 frame of the "animated brushtip", with the option that each frame matches "direction" rather then being "incremental", and thats how you get the faux-light! The cool thing is that you can extract and edit the animated brushtip in Krita e.g. this one "https://github.com/Draneria/Metallics-by-Draneria_Krita-Brushes/blob/main/brushes/memileo_360light-PHOTO-A_06-incremental.gih https://github.com/Draneria/Metallics-by-Draneria_Krita-Brus..." Which means theoretically, you could use photo editing to change the height I think!
    - itishappy 2y ago
      Coolest thing I've seen all day. Thanks!
    - stuaxo 2y ago
      Great stuff, it's good to hear how brushes work in these programs, reminds me of a great chat with one of the MyPaint devs.

retSava 2y ago

Thanks for sharing! These look amazing and I look forward to trying them out.

getToTheChopin 2y ago

Lovely textures, thank you for sharing. Will try them out in some generative art projects I'm working on!

metallicss 2y ago

Great work! I have been looking for an excuse to try out Krita. This just might be it. Shameless plug: I am also a sucker for metallic aesthetics, and I made this FOSS library to enable realistic metal textures on the web (for buttons, cards, input elements, etc.): https://www.metallicss.com https://www.metallicss.com

esperent 2y ago
Very nice, I approve of anything that goes against the Material Design hegemony. One question though: there's a (relatively) large delay updating the demo when I change the convexity. Is this something that comes from the update script or is the effect itself slow? Because I don't think I've ever seen a CSS effect that takes a half second to update before.
- jraph 2y ago
  There are a lot of canvas in there, I doubt CSS is involved much in drawing this effect.
  - esperent 2y ago
    I checked out the source, there's only a single canvas being used to render a base64 PNG. The PNG is just a 400x400 spherical reflection map, which is basically a required component of any metallic effect. I don't think that would cause a slowdown.
mattkevan 2y ago
Very cool! It'd be fun to use the webcam to create live reflections.
draneria 2y ago
wow, that's amazing! I'm gobsmacked you can make something like this with CSS, that is so cool
- kroltan 2y ago

Aeolun 2y ago

Honestly, I’m most impressed by that fantastic demo gif.

atmanactive 2y ago

Just a small favor please: in your README.md file, on the first mention of word Krita, make a link to Krita repository or website. Thanks.

draneria 2y ago
Added! Thank you for pointing that out (´｡• ᵕ •｡`)

Llamamoe 2y ago

So what does it do? Create a normal map while drawing?

draneria 2y ago
On the right track but not quite! Every brush in art software uses an image (raster or auto-generated) to paint with, called a "brushtip". Usually, the brushtip only gives information about which bits are opaque, and which arent - the shape! However in Krita, theres another dimension you can define; value, or lightness. So there's nothing being generated or created while drawing, its just that some very smart people have coded Krita for the "brushtips" to do more as a baseline. Not every software works exactly the same ofcourse! This is just my beginner level understanding of it all, I hope that helps
- short_sells_poo 2y ago
  Photoshop and other painting software had "intelligent" brushes for a while now. These try to simulate stuff like paint mixing (even watercolor), opacity and texture.
  - draneria 2y ago
    Could you give me an example? I'd love to know more about the watercolour paint mixing. If you meant the "live tip" settings of Photoshop, you can do all that in Krita too, using the "texture", and "mask tip" features. RGBA seems to definitely be something Krita has over Photoshop, but I could well be wrong! by the way, there are other softwares like Rebelle that try to truly simulate traditional mediums - bordering on a whole-ass physics engine that works completely different in the backend from PSD/Krita. Unfortunately its a paid software so yeah :s
    - short_sells_poo 2y ago
      It's been a while, but a bit of googling turned up this: https://www.adobe.com/uk/learn/fresco/web/realistic-watercolor-painting https://www.adobe.com/uk/learn/fresco/web/realistic-watercol...

jeremyscanvic 2y ago

That's cool! Great work!

bloopernova 2y ago

This is fantastic, the paint looks great, excellent job :)

isodev 2y ago

Krita is fantastic, and these look gorgeous! Thank you so much for your work.

lttlrck 2y ago

Amazing. This motivates me to try Krita. Well done.

michael0x11 2y ago

Pretty neat tech - the RGBA brush engine in Krita is doing something fundamentally different from PS's basic alpha masks. Being able to encode directional data in the brush tip itself opens up some interesting rendering possibilities. Been messing with similar effects in PS using layer styles but this seems way more efficient.

draneria 2y ago
Exactly! it is really incredible. I've not used Photoshop much, I'd be curious to know how the two face-off in the realm of brush features haha