Imgui rendered fonts do not look as crisp as in the other menus with the software renderer

[NetSysFire]

Describe the bug

Attach save file

n/a

Steps to reproduce

1. Look at curses menus with lots of text. advanced inventory manager in this case.
2. Press ? to look at keybindings.
3. Brain immediately complains that the fonts look.. blurry? They definitely look off and not as crisp as the menu just before.

Expected behavior

Fonts look as crisp as in the ncurses menus.

Screenshots

No response

Versions and configuration

• OS: Linux
  • OS Version: LSB Version: n/a; Distributor ID: Arch; Description: Arch Linux; Release: rolling; Codename: n/a;
• Game Version: cdda-experimental-2024-04-14-2000 2716469 [64-bit]
• Graphics Version: Tiles
• Game Language: System language []
• Mods loaded: [ Dark Days Ahead [dda], Disable NPC Needs [no_npc_food], Slowdown Fungal Growth [no_fungal_growth], Bionic Professions [package_bionic_professions] ]

Additional context

No response

[Qrox]

Looks like the ImGUI window is using a different font. For example the r looks different from the non-ImGUI window. Also, if you look closely you can see that the ImGUI font has gray pixels which suggests that it fails to use the bitmap version of the vector font. Could you post your config/fonts.json?

[NetSysFire]

I do not remember changing anything of this, so it is probably the default.

{
  "typeface": [ "Terminus", "unifont" ],
  "map_typeface": [ "Terminus", "unifont" ],
  "overmap_typeface": [ "Terminus", "unifont" ]
}

Additionally, have all the font-specific options in options.json I grepped::

{ "info": "Highlight selected item's contents and parent container in inventory screen.  \"Symbol\" shows a highlighted caret and \"Highlight\" uses font highlighting.", "default": "Default: symbol - Values: symbol, highlight, disable", "name": "INVENTORY_HIGHLIGHT", "value": "symbol" },
{ "info": "If true, will display scrolling combat text with Unicode font.", "default": "Default: True", "name": "ANIMATION_SCT_USE_FONT", "value": "true" },
{ "info": "If true, vector fonts may look better.", "default": "Default: False", "name": "FONT_BLENDING", "value": "true" },
{ "info": "Set the font width.  Requires restart.", "default": "Default: 8 - Min: 6, Max: 100", "name": "FONT_WIDTH", "value": "8" },
{ "info": "Set the font height.  Requires restart.", "default": "Default: 16 - Min: 8, Max: 100", "name": "FONT_HEIGHT", "value": "16" },
{ "info": "Set the font size.  Requires restart.", "default": "Default: 16 - Min: 8, Max: 100", "name": "FONT_SIZE", "value": "16" },
{ "info": "Set the map font width.  Requires restart.", "default": "Default: 16 - Min: 6, Max: 100", "name": "MAP_FONT_WIDTH", "value": "16" },
{ "info": "Set the map font height.  Requires restart.", "default": "Default: 16 - Min: 8, Max: 100", "name": "MAP_FONT_HEIGHT", "value": "16" },
{ "info": "Set the map font size.  Requires restart.", "default": "Default: 16 - Min: 8, Max: 100", "name": "MAP_FONT_SIZE", "value": "16" },
{ "info": "Set the overmap font width.  Requires restart.", "default": "Default: 16 - Min: 6, Max: 100", "name": "OVERMAP_FONT_WIDTH", "value": "16" },
{ "info": "Set the overmap font height.  Requires restart.", "default": "Default: 16 - Min: 8, Max: 100", "name": "OVERMAP_FONT_HEIGHT", "value": "16" },
{ "info": "Set the overmap font size.  Requires restart.", "default": "Default: 16 - Min: 8, Max: 100", "name": "OVERMAP_FONT_SIZE", "value": "16" },
{ "info": "If true, use SDL ASCII line drawing routine instead of Unicode Line Drawing characters.  Use this option when your selected font doesn't contain necessary glyphs.", "default": "Default: True", "name": "USE_DRAW_ASCII_LINES_ROUTINE", "value": "true" },

[Qrox]

So, judging from the r character, the non-ImGUI window is using Terminus, whereas the ImGUI window is using unifont, so this is indeed related to #73061. The blurry characters is actually a separate issue related to unifont. The unifont we're using is a vector font without embedded bitmap font for specific font sizes, so it renders across pixel boundaries resulting in gray pixels.

I made a modified unifont file with embedded bitmap font for font size 16 in #66749 which can probably work around this problem. That PR has stalled, but you can try replacing data/font/unifont.ttf with the version in that PR and see if it fixes the blurry characters.

I'm not sure if we can fix it for all font sizes though. Previous I tried to shift the glyphs horizontally by a fraction of a pixel but that still resulted in blurry characters. Subpixel rendering might fix it but it was more complicated than I expected. Maybe we can let the user turn antialiasing on or off for individual fonts, which might fix it.

[NetSysFire]

That PR has stalled, but you can try replacing data/font/unifont.ttf with the version in that PR and see if it fixes the blurry characters.

I did but it does look even worse in this case than without the modified font. Worth a try though.

[Qrox]

I did but it does look even worse in this case than without the modified font.

Could you post a screenshot?

[NetSysFire]

Sure, with your custom font:

Without:

[Qrox]

Looks like it's still using the vector version of the font. Not sure if there's something wrong with the font or how ImGUI handles embedded bitmap font.

[Qrox]

Looks like it uses the bitmap glyphs for Chinese characters but uses the vector glyphs for English characters, and the color is also different. Intriguing. @katemonster33 Do you have any idea why this happens?

[katemonster33]

Looks like it uses the bitmap glyphs for Chinese characters but uses the vector glyphs for English characters, and the color is also different. Intriguing. @katemonster33 Do you have any idea why this happens?

This happens because of #72579 , to get around ImGui's font rendering so that we can draw CJK characters without needing to cache all of them, I made ImGui call into CDDA's font rendering code to draw any character which doesn't exist in its cache.

We could have the same logic apply to all font drawing in ImGui, just have every character drawn by CDDA's code. This would have the added benefit of fixing the issue where ImGui does not respect the user's font choice. The only issue I could see would be the extra CPU usage, because ImGui screens tend to draw more frequently than the old screens. ImGui has this nice logic where it renders text in huge batches using SDL_RenderGeometry which makes it very efficient. But maybe the CPU hit won't be too bad.

[katemonster33]

very weird. in windows the imgui UIs look fine.

[katemonster33]

I zoomed in on the 'X' button on the window. Linux on top, Windows on bottom. seems like transparency is off in linux? but why? so strange

[Qrox]

Is ImGUI using SDL for font rendering? If so you might want to check what blending mode and font hinting is used in Linux and Windows.

[katemonster33]

Fooled around in the options a bit. This appears to be an issue related to having the Renderer option set to "software". On opengl setting the problem is gone, the window looks exactly like it does on Windows.

[NetSysFire]

My settings, for reference. I am also using the software renderer since ages.

[NetSysFire]

I can confirm that the fonts look so much more crisp on opengl

[Qrox]

I am using direct3d11 and the font also looks blurry. Changing to opengl does not fix it either. My game is compiled with MinGW-w64, if that matters.

[katemonster33]

@Qrox that's very curious. I believe we've narrowed down this issue to SDL for certain though.

The actual function used by ImGui to draw to the screen is SDL_RenderGeometryRaw . ImGui boils drawing of everything down to one giant draw command that is a large pile of vertices that all reference one giant font atlas texture. I don't believe the 'X' of the window is a font texture so I'm not sure exactly how it works with that function, only that it definitely does all use that.

Anyway, I am only explaining that because CDDA definitely does not use that function anywhere. Maybe what we are seeing is a bug related to that function with certain configurations?

[vetall812]

Just checked build:

- OS: Windows
    - OS Version: 10.0.22631.4112 (23H2)
- Game Version: cdda-experimental-2024-08-29-0513 673d845 [64-bit]
- Graphics Version: Tiles

in my case ImGui is blurry with any renderer except opengles2 (this one shows only black screen and I have to change settings manually in file).

It can be linked with #75920

Well I managed to remove blur effect, but with side font. OpenGL+font blending works fine for fonts that are not pixel perfect.

[sonphantrung]

75920 didn't quite fully solve the problem as it uses default UI font (Terminus)

Probably something with the Catapult's user/game config

[IdleSol]

cdda-windows-tiles-x64-2024-08-30-0310

[EN]

[RU]

Options menu

In the settings menu, English text is less blurred. Russian text is not blurred at all. Most likely because of a different font. Default settings.

[vetall812]

75920 didn't quite fully solve the problem as it uses default UI font (Terminus)

Probably something with the Catapult's user/game config

I tried to exclude external user settings from this issue and have tests with local game settings as well as font files.

[vetall812]

75920 didn't quite fully solve the problem as it uses default UI font (Terminus)

try to use absolute paths to fonts for now. (#76057)

[juur]

This is still broken:

from the demo (blurry)

from the link on the menu to launch the demo (not blurry)

(Windows, opengl rendered but same under directx)

[Lumi-Virtual]

i did a few quick tests and it seems like imgui is using the vector fallback set of characters from terminus instead of the bitmap characters. except for the question mark character, as well as the russian characters it seems, and so id guess that its only using the vector fallback for like, the engilsh alphabet, numbers, and some but not all of the punctuation characters (since the brackets and period also look wrong)

here i modified the D and the ? in the vector fallback set and only the D changed. you can see how the ? is positioned slightly higher than the rest, which is consistent with the bitmap set of characters compared to the vector fallback set.

[katemonster33]

@NetSysFire please retest now that #76420 has been merged

[IdleSol]

I don't really like the fact that the text is in bold. But that's probably because I'm used to the old version.

UPD. cdda-windows-tiles-x64-2024-10-28-0933

UPD2.

[katemonster33]

Looks like the blurriness is gone. If you look closely, the window "X" button is still corrupted

[IdleSol]

UPD. Oh, it's about the game running on windows. I have a windows game running on linux.

[NetSysFire]

@katemonster33 I am unsure how I am supposed to retest. Yes, the new font looks fine but it also introduces new issues that need reintroduction of a monospace font for some things, e.g gravestones. And if I read that right, the issues lie with some pixel stuff related to that monospace font. So while saying this is fixed now is technically correct, I anticipate it will come back to bite us when the monospace font gets used again, which should be very soon. Of course, this can be incorrect as I am by no means an expert on these things.

Somewhat less related but that X is also mildly overlapping the text, probably related to the ". I have seen this happening multiple times with varying severity. This one is mild though.

[katemonster33]

@NetSysFire I suppose it's up to you since you wrote the issue, but my gut feeling is that the original issue describes a problem where the text on ImGui screens is garbled and barely readable when compared to text on the rest of CDDA. The other issues should get their own issue numbers IMO