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[Tutorial] Render text ingame⚓︎

Fonts used by the game⚓︎

The Following fonts are used by the game and can be used with the Font() class:

Font Name Ingame Name/s Ingame Example Ingame Usage Link to font
Droid Sans droid Example Droid (Not used ingame) Droid Sans
PF Tempesta Seven (Condensed) pftempestasevencondensed Example PF Tempesta Seven HUD Elements like coin/key counters PF Tempesta Seven
Team Meat Font teammeatfont10
teammeatfont12
teammeatfont16
teammeatfont16bold		 Example teammeatfont10
Example teammeatfont12
Example teammeatfont16
Example teammeatfont16bold		 Main Menu Elements
Pop-Ups
Timer / Score Elements		 Team Meat Font without Bold
Terminus terminus
terminus8		 Example Terminus
Example Terminus8		 Debug Console / Isaac.RenderText() Terminus
Luamini
(Repentance)		 luamini
luaminioutlined		 Example luamini
Example luaminioutlined		 Stats HUD
Upheaval upheaval
upheavalmini (Repentance)		 Example Upheaval
Example Upheavalmini		 Streak text Upheaval
mplus (Japanese) mplus_10r
mplus_12b		 Example mplus_10r
Example mplus_12b		 Replacement for all fonts aboth for Japanese translation.
10r is pf "Tempesta seven" / "Team Meat" replacement
12b is "Upheaval" replacement		 PixelMplus
(M+ Fonts)
kr Font (Korean) kr_font12
kr_font14		 Example kr_font12
Example kr_font14		 TBD No source found right now
Team Meat Font (Korean) kr_meatfont14 Example kr_meatfont14 TBD - Not available -

Basics of rendering a text⚓︎

First we need to have a look at the basic process of writing on the screen. here is a sample code:

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local testmod= RegisterMod( "testmod" ,1 );

local function onRender(t)
    Isaac.RenderText("Sample text", 50, 30, 1, 1, 1, 255)
end

testmod:AddCallback(ModCallbacks.MC_POST_RENDER, onRender)

Result:

The game uses the font-file "terminus.fnt" in order to render and display this text. this cant be changed. Luckily for us, this file contains "sprites" for all normal ASCII characters that exist out there (256 to be precise).

Rendering text with a different font⚓︎

We can render any kind of text with a different font as well. This can be done by using the "Font()" class and its functions.

Example code:⚓︎

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local f = Font() -- init font object
f:Load("font/droid.fnt") -- load a font into the font object
f:DrawString("droid",60,50,KColor(1,1,1,1,0,0,0),0,true) -- render string with loaded font on position 60x50y
dlc3-language specific fonts: 
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local f = Font() -- init font object
f:Load("resources-dlc3.jp/font/mplus_10r.fnt") -- load a font from the Japanese data package
f:DrawString("mplus_10r",60,50,KColor(1,1,1,1,0,0,0),0,true) -- render string with loaded font on position 60x50y

Quick overview of common Fonts that can be drawn:⚓︎

Render Special Characters⚓︎

The game allows us to write anything into the "displayed text" argument that is part of the ASCII standard for characters. For characters a-z, 0-9 and ,.#+;:_'*~° this works without any problems and without using any kind of "hack". Now if we just strait up try to type in ' ä ' or ' ß ' to let it render as text, it will not look as intended. In order to fix this problem we have to use the "raw" version of said characters. Example:

\197

prints:

Ä

So in order to print special characters, just replace them in the code like this:

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Isaac.RenderText("S\228mple text", 50, 30, 1, 1, 1, 255)

prints:

Sämple text

List of all supported characters and their counterpart⚓︎

Creating .fnt files⚓︎

The Developer __Kilburn_ mentioned that fonts can be created using this Tool: https://www.angelcode.com/products/bmfont.

The best results can be made by converting Bitmap fonts, since they allow for smaller fontsizes.

Font Settings:

  • Font - choose a font thats very readable in small sizes (~8-10px height)
  • Charset - Unicode
  • Size - the general size of the characters in pixels. normal values are between 10 and 16
  • Height - can be used to squish/strech the
  • Match char height - the charactersize will be choosen based on the character, and not the size defined in Size
  • Bold / Italic - What font styling should be used
  • Output invalid char glyph - Characters that dont have a sprite will be put on the spritesheet, too. This can create holes in the spritesheet

  • Do not include kerning pairs -

  • Rasterization - used to smooth the font sprites. Not recommended for Isaac since we want pixel-perfect fonts!

  • Outline thickness - Define if an outline should be drawn around the character. In Isaac, this is always ~1px

Export Options:

  • Padding - Padding around each character, in pixels
  • Spacing - Space between characters, in pixels

  • Equalize the cell heights - will align all characters in a way, so they take up the least space vertically. off = they group in more uniform rows

  • Width / Height - Width and Height of each character spritesheet. If spritesheet isnt big enough, multiple files will be created

  • Bit depth - how many Bits should be used per color. ALWAYS choose 32 bit!

  • Pack chars in multiple Channels - Dont use this. We need all channels for out font because of transparencies!

  • File format - Choose Binary to create ".fnt" files

  • Textures - always set it to "png"
  • Compression - (only one option available)
Last update: December 12, 2023