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PavolUlicny

@PavolUlicny

Joined June 1st, 2026

  • 39Devlogs
  • 1Projects
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15yo dev, rn working in C++ on a terminal software rasterizer called rasterminal.
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4h 33m 9s logged

Added more CLI flags for startup customizability

Added flags to set the camera pitch, yaw and zoom on startup. Now every runtime-settable variable can be set during startup through the CLI. The R button now resets the state to the CLI set state, not to factory defaults.

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4h 26m 39s logged

Added –spin-speed and –spin-direction flags

Added CLI flags for the spin speed and direction. The speed is in deg/s and the directions is simply left or right. Here’s what 1000 deg/s looks like spinning to the right:

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8h 41m 21s logged

Did a bunch of small code quality and usability improvements

Fixed a Windows bug that crashed the program on model sizes bigger than 2GB, improved the orbit usability (fixed mouse drag behavior when models are turned upside down), and did a few cleanups and fixes in the CLI parsing.
I’m planning on adding a few CLI flags that I think can be very useful for some people, specifically better spin settings, starting camera angle/zoom control and a few more.

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39m 13s logged

Finally merged color-fallback, I can move onto other things

The branch is finally merged. I’ve accumulated a bunch of usability and code quirks and issues that i can finally get to now that the branch is merged. So now I’ll be reworking all the CLI flags, camera and other components. And we also passed the 700 commit mark with this merge!

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4h 56m 40s logged

Changed the 24bit to 256 color palette conversion logic

Until now, the conversion picked the closest color possible mathematically. But from testing on a bunch of different models, I’ve realized that it doesn’t actually look very close to the human eye. So I swapped it out for a different method, called CIELAB distance. Now it still doesn’t look perfect, but as a fallback for older terminals it’s close enough.

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9h 13m 33s logged

Working on a –color compatibility flag

The color terminal compatibility thing I was working on has landed in the branch, now I’m adding a –color flag to override the automatic capability detection for situations like ssh, where we almost always degrade to the 256 color pallete for maximum compatibility. So now you’re gonna be able to use the right color mode even if the automatic detection is wrong for your situation.

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10h 21m 8s logged

Working on terminal color capability detection

I am adding automatic terminal capability detection, meaning that rasterminal will get the terminal type and either refuse to render on super old or “dumb” terminals, degrade on some terminals and render normally on modern ones.

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5h 9m 13s logged

Working on adding 256 color support

Some older terminals can’t display full 24bit RGB colors and use a 256 color palette instead. I’m adding a fallback so the older terminals can still use rasterminal. It still calculates the full old RGB colors, but then just maps them to the nearest 256 color with LUTs.
On a side note, I switched my terminal emulator from Kitty to Ghostty.

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10h 24m 18s logged

Working on portability

Did a bunch of small fixes and improvements in the last ~week. Right now I’m on vacation for the next couple of days, so I won’t be active. I am currently working on broader terminal and platform support, so older systems and terminals will be able to run cleanly with some fallbacks or will fail loud with a clear message about what isn’t supported.

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5h 11m 33s logged

Completely removed the shadow map

Before, rasterminal built a shadow map on model load and displayed it during runtime. I now completely removed it, because it was slower during load, slower during runtime, sometimes looked broken on curved surfaces and added essentially no value.
Here, the first picture is with the shadow map and the second is without.

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13h 26m 5s logged

Wasted 7 hours of my life

Did a bunch of smaller cleanups and fixes, and then I tried to template the unlit and lit paths in the rasterize_flat function, which turned out to be a performance regression. Awesome.

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5h 46m 24s logged

Added a release workflow, manpage and changelog

I added a github release workflow that works alongside the changelog and released the first pre-release version:
v0.1.0-alpha.1
Also added a manpage and an install target to make and cmake that installs the binary, docs and manpage into the path.

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5h 10m 59s logged

Pararelized the wireframe shading mode

I did a bunch of small things alongside it, but the main feature for this devlog is the pararelization of the wireframe shading mode. It was previously fully single threaded, but it wasn’t that hard to pararelize, i just had to make the function it used to write into the framebuffer (draw_line) CAS atomic, to avoid race conditions. Now wireframe is the fastest shading mode in basically all scenarios.
Below, you can see a performance benchmark (built into rasterminal using a flag) with wireframe mode on a super dense mesh and how the wireframe mode looks like (you can also cycle the colors).

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1h 54m 12s logged

Split the tests into sub-directories

The test suite is now very long (20k LOC across 47 files), so i decided to split it into sub-directories instead of just having 47 files in one flat dir. It’s cleaner, more maintainable and looks better.

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4h 59m 25s logged

Completely removed gouraud shading mode

Gouraud was previously the main shading mode, but now I’ve just completely removed it. It was by far the slowest, while not adding any actual value to the project. Blinn-phong lighting is faster AND it supports more features (normal maps, etc.), so there was just no point in keeping gouraud. Now that I’ve removed it, the project has less code to maintain and a faster default shading mode with more features.

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3h 45m 35s logged

Added proper OBJ bump map support

OBJ bump maps are textures for simulating bumps and wrinkles on models. Blender used to author bump maps as normal maps for some reason, so I made it automatically detect if it’s a normal map disguised as a bump map and handle it well, since there are a lot of old Blender OBJ models in the wild. But it also handles bump maps as bump maps normally, so it’s basically the best of both worlds.

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6h 51m 44s logged

Added texture transform into the TEXCOORD branch and merged it into main

Not that hard, just read it, pass it to the rasterizer and then display it. I did have a very sneaky bug in the loader that made the whole feature render wrong, where I just had to negate one value to fully fix it, but now everything fully works.
Below you can see the Khronos test asset for texture transforms. (tick means fully working, clearcoat is not yet implemented so it doesn’t show as working)

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5h 12m 35s logged

Added TEXCOORD_1 support

glTF sometimes authors a second TEXCOORD set (first one is TEXCOORD_0, 0 indexed numbering). The official spec only requires support for the first two TEXCOORD sets, even though there can theoretically be any number of them in a model. That said, major model exporters don’t author any more than the two sets, so to avoid extra work, I only added support for 0 and 1.
(not merged into main yet, I want to polish it a little and maybe add KHR_texture_transform support on top of it first)

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7h 36m 48s logged

Optimized the transparent cleanup path in the renderer

After rendering the model in the transparent path, we have to resolve the transparent pixels, which basically just pastes in the pixels behind it and sometimes tints it based on how dark and what color the transparent material is (tinted glass will make the things behind it darker, normal glass will be mostly completely untinted). Before, the resolve function looped over every single pixel in the frame, even non-transparent and background ones. This is obviously wasteful. So I made it find the smallest box, in which all the transparent pixels of the whole frame fit and just looped over that. It recovered the overhead of the transparent resolve on models with smaller transparent parts, but it also made fully transparent or mostly transparent models slightly slower (it still basically loops over almost the whole screen on these types of models, so keeping track of the smallest bounding box while also still doing the same work as before made it a little slower). But the performance benefits for the average model outweighed the losses on rare fully transparent models. In the image, you can see the benchmark results versus the baseline.

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6h 39m 38s logged

Made the shading mode branches compile time instead of runtime in the renderer with templates

Did the same template if constexpr (compile time if branches) thing that we already do for opaque/transparent models with the shading mode (was a runtime per triangle if branch before), which improved performance. It basically just makes a new copy of the function for each shading mode x each transparency mode, so 4x2 which is 8 slightly different functions and uses the correct one on each call. That increases binary size and icache pressure, but drops per triangle or per pixel if branches that hurt performance, so it’s an overall performance win. Benchmarked across a ton of different resolutions, models, shading modes, etc. (the benchmark by itself took like 2 hours to run)

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