Mode 13h: MS-DOSify!

[](https://github.com/Hand-Lock/mode-13h/blob/main/LICENSE)

# Mode 13h: MS-DOSify!

*An **Iris** shader pack for Minecraft that recreates the look of late-90s **MS-DOS** 3D graphics with deliberate retro accuracy.*


**Mode 13h: MS-DOSify!** is not just a generic “pixelation” shader. It aims to reproduce the actual visual limitations and quirks that gave old DOS-era 3D games their unmistakable look: low resolution, affine texture warping, limited color depth, stepped lighting, billboarded sprites, and carefully tuned fog.

It has currently only been **tested on Minecraft `1.20.1`**, but it **should also work on other versions**.

> **Recommended render resolution: `1280 x 800`**
> The shader pack is designed to **downscale by 4x** to an internal **`320 x 200`** image, matching classic **Mode 13h** output.
> For the most authentic look, stretch the final image to **`4:3`** to reproduce the era’s **non-square pixels**.

## 🧾 Why This Exists

A lot of “retro” shaders stop at chunky pixels and call it a day.

**Mode 13h** goes further. It tries to recreate the specific rendering artifacts that defined old DOS-era 3D, including the quirks modern graphics usually try to hide or eliminate. The goal is not just to look old — it is to feel like an actual late-90s PC pushing textured 3D slightly beyond its comfort zone.


## ✨ Features

### 📺 Authentic low-resolution output

– The image is downscaled to a **Mode 13h-style `320 x 200`** internal resolution.
– This gives the shader pack the crunchy image structure typical of classic DOS graphics.

### 🧱 Affine texture mapping

– Textures use **affine mapping** instead of perspective-correct mapping.
– This recreates the classic **texture wobble and warping** seen in older software-rendered 3D games.

### 🎨 Retro palette reduction

– Colors are quantized to a **256-color** style output.
– An optional **`6 x 6 x 6`** palette provides a more limited **216-color** look.

### 💡 Stepped lighting

– Lighting is **quantized** into configurable brightness steps.
– Setting it to **16** steps gives something closer to vanilla Minecraft’s light progression while keeping the retro feel.

### 🌫️ Tuned fog

– Fog is adjusted to better match the mood and readability of old-school 3D visuals.
– It helps sell distance the way older games often did.

### 🪧 Billboarded sprites

– Many blocks and decorations render as **2D billboards** that always face the player.
– This mimics the sprite-based tricks commonly used in older 3D games.

## ⚙️ Configuration

The shader includes a **configuration menu** with several options so you can fine-tune the effect to your taste.

You can adjust things such as:

– **Fog tuning parameters**
– **Affine mapping parameters**
– **Color reduction mode**, including switching between **256-color** and **216-color**
– **Add-on compatibility toggles**, which can be enabled or disabled individually
– **Resolution reduction**
– And other settings for dialing in the exact retro look you want

## 🔧 Technical Notes

– Built for **Iris** and compatible with **Oculus**
– Currently only **tested with Minecraft `1.20.1`**, though it should work on other versions as well
– Targets **OpenGL `4.1`**, so it can also run on **macOS**

## 🧩 Add-ons

**Mode 13h** also has optional companion add-ons that expand the billboarding system.

> **Important:** Add-ons are **not included** with the shader pack. They must be **downloaded separately**.

### 🪧 Flatter Signs

[**Flatter Signs**](https://modrinth.com/mod/flatter-signs) is a mod that changes signs into **cross/hatch models**, allowing Mode 13h to billboard them like flowers or grass.

Without the shader pack, those signs simply render as flat cross/hatch objects. With **Mode 13h** enabled, they become proper DOS-style billboarded signs.

### 🧱 Billy-Boarding *(WIP)*

**Billy-Boarding** is a resource pack that changes the **`.json` block models** of selected blocks so they become **cross/hatch-based** and therefore compatible with the shader’s billboarding system.

If you install these add-ons, you can enable or disable their dedicated support from the **shader configuration screen**.

## 🌌 Recommended with a Stylized Sky

For the best overall presentation, it is recommended to pair **Mode 13h** with a **stylized skybox**.

At the moment, the recommended choice is [**Anime Sky**](https://modrinth.com/resourcepack/anime-sky).

A bespoke skybox made specifically for **Mode 13h** may come in the future.

## ❌ What It Is Not

– Not just a simple “pixelation” filter
– Not a generic CRT-style retro effect
– Not a clean or modernized take on retro visuals

**Mode 13h** intentionally embraces visual instability, harsh quantization, and awkward old rendering tricks — because that is the whole point.

## 🖇️ Credits

– **Shader pack & idea:** *HandLock_*

> *“If the textures don’t wobble, it’s not old enough.”*

missing textures

# Missing Textures shader

This shader makes every block in the game have the pink/black squares missing texture.
It also has settings to customize it:
– r g b values for the pink parts
– missing sun/moon texture
– keep terrain colors
– keep original colors


The shader should be compatible with every version of Optifine and Iris

Miniature Shader


Miniature is a natural take on Minecraft shaders. It offers blocky shadows and reflections in water, ice and
other commonly reflective blocks, and a slight overhaul of emissive lighting; all in a very lightweight way. Its goal, above all else, is to keep with Minecraft’s model-like appearance without compromising performance.

Miasma

Chippa256 shader

Very basic but effective shader that applies dithering and other vintage screen effects to make the iconic low-res look and feel of Minecraft seem even more low-res!

There isn’t much to say about this shader for now.

Mellow

### Features
– Broad mod compatiblity: Distant Horizons, Voxy, Colorwheel etc.
– Several preset color schemes
– Extensive & customizable fog system
– Multiple styles of clouds
– Lightmap or shadowmap based shadows
– Extensive olor grading (saturation, exposure, color balancing tool etc.)
– Easily adjustable colors
### Compatibility
– At the moment only versions 1.17 and up are being tested. Earlier versions may or may not work.
– Modern Nvidia, AMD and Intel gpus are supported on both Windows and Linux. Macs may or may not work.
– Please use the latest Iris version (any version that supports custom uniforms should work). Optifine has some small bugs, but it should also mostly work.

minecraft CRT

# mCRT

mCRT is a simple highly customizable analog horror shader primarily designed to emulate CRT monitors.

—
### Features
– Customizable pixel size
– Various colorful overlays
– Fully adjustable fog
– Customizable scan flicker
– Variable screen static
– Chromatic aberration

—
—

This shader is an adaptation (and expansion) of Xor’s wonderful CRT shader for GameMaker, which can be found [here](https://mini.gmshaders.com/p/gm-shaders-mini-crt).

MC VHS

## ⨠ Notes
Despite what the versions may say, all MC VHS versions 2 and above will work on _most_ versions of Iris (and probably Optifine, though I haven’t tested). It would be a hassle to constantly update what versions it supports, so I’m just saying it here. Thanks for using my shader!

# ⨠ What is MC VHS?
MC VHS is a Minecraft shader, duh. Jokes aside, this shader aims to apply a somewhat realistic VHS filter to the game itself, as opposed to a filter applied in post. Compared to other shaders which incorporate VHS effects, this shader aims to be a bit more realistic than just “slap on some chromatic aberration and scanlines”, which I will expand upon in “What does MC VHS do?”. Whether you use it for an ARG, nostalgia bait or what have you, so long as my work is used for something creative, I’m happy.

## ⨠ What does MC VHS do?
Here I’ll talk a bit more in-depth about the features and how it works.

First off, as stated previously, MC VHS is a slightly more realistic VHS effect for minecraft. Whereas most other effects will use some combination of chromatic aberration, scanlines and distortions, my shader tries to emulate how videos are compressed, the main features being compression in the YIQ colour space, colour & luminance noise, post-sharpening and interlacing.

## ⨠ What next?
Sorry it took so long for this, I really was in college, but I have also had Version 2 on my hard drive for quite a while now so there isn’t much of an excuse… I won’t promise I’ll update this to the extent I was doing, I may add some features in the future, or mess around with it a bit, but not as much.

Outline Shader

Mathematically Unplayable

# Warning!
> **_!! INCLUDES FLASHING COLORS !!_**

# About

“Mathematically Unplayable” is an experimental shaderpack for Minecraft: Java Edition designed for OptiFine. It dramatically alters the game’s visual presentation by applying a series of mathematical transformations to world geometry, textures, and screen output. This pack is intended for users interested in exploring extreme visual effects, understanding shader capabilities, and experiencing Minecraft in a uniquely distorted and chaotic way. Visual examples showcasing the shader’s transformative style can be found in the “Gallery” section.

# Showcase
2.0.0:

1.0.0:

# Core Features & Visual Effects

This shaderpack is built around two main stages of visual manipulation, controlled by a global “Mess Intensity” slider:

1. **GBuffer Stage – World Deformation (Static):**
* **Terrain Geometry Warping:** Vertex shaders significantly displace terrain vertices using trigonometric functions based on their original positions and the “Mess Intensity” setting. This results in a permanently fractured, warped, and unpredictable landscape.
* **Texture Coordinate Distortion:** Texture coordinates for terrain blocks are manipulated, causing textures to swim, stretch, and misalign on block surfaces.
* **Depth Buffer Alteration:** The fragment shader for terrain intentionally writes chaotic depth values, leading to extreme Z-fighting, objects rendering through each other, and a general breakdown of spatial coherence.

2. **Composite Stage – Post-Processing Effects (Animated):**
* **Screen-Space Coordinate Distortion:** The entire rendered frame is subject to animated distortions, including swirling patterns around the screen center and undulating waves that warp the view.
* **Psychedelic Color Transformation:** Color channels (RGB) are dynamically modulated using time-based (`ftime`) trigonometric functions, resulting in constantly shifting, vibrant, and unpredictable color palettes across the screen.
* **Glitch & Scanline Overlays:** Includes effects like periodic color channel swapping (e.g., RGB to GBR) and animated horizontal scanlines to further enhance the “broken” aesthetic.

# Key Technical Highlights & Customization

* **Slider:** A single, easily accessible slider (0-100) allows users to fine-tune the overall magnitude of all visual distortions and color effects, from subtle to extreme.
* **Button Switches:**
There are 3 buttons, used to turn gbuffers_terrain, gbuffers_skybasic and composite ON/OFF
* **Educational Focus:** All GLSL shader files (`.vsh`, `.fsh`, `settings.glsl`) are extensively commented (with AI assistance) to explain the code logic and the techniques used. This is intended to serve as a learning resource for those interested in shader development and modification.

# Feedback & Support:
Found an issue or have a suggestion? Please report it here: [Issue Tracker](https://github.com/JamesCoalchiPortfolio/MathematicallyUnplayable/issues)

# Installation

* Modrinth launcher:
1. Open the mathematically unplayable shader page.
2. Click install.
3. Choose instance.
4. Start the game.
* Official launcher:
1. Open the mathematically unplayable shader page.
2. Download the “Mathematically Unplayable” shaderpack ZIP file.
3. Place the ZIP file into your Minecraft `shaderpacks` folder:
4. Start the game