AVS Shader Screensaver

A portable OpenGL screensaver for Windows that randomly picks from 46 curated GLSL fragment shaders embedded directly in the executable. No external files needed — a single .exe (or .scr) contains everything.

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Features

• 46 embedded GLSL shaders — fractals, terrain, aurora, oceans, fire, clocks, cyberpunk cityscapes, glass refraction, fireworks and more
• Fully portable — all shaders are bundled as PE resources inside the executable. Copy it anywhere and run
• Multi-monitor support — renders across all monitors using the virtual screen dimensions
• Dead-zone culling — automatically detects mismatched monitor layouts (different resolutions/orientations) and injects per-pixel monitor bounds checking into every shader at runtime. Pixels in the gaps between monitors are skipped via early-return, saving GPU cycles on non-rectangular multi-monitor setups
• Real-time clock — shaders that use iDate receive actual system time via GetLocalTime(). When a shader has its own clock display, the built-in GDI overlay clock is automatically hidden
• GDI clock overlay — Segoe UI time/date display with drop shadow, anchored to primary monitor bottom-left. Disabled when the active shader provides its own clock
• Screensaver compatible — handles /s, /p, /c, /a command-line flags. Rename to .scr and install via right-click or copy to System32
• Single instance — mutex with 3-second timeout prevents multiple copies from running. Mutex is released before LockWorkStation() to avoid stalling the next instance on exit
• GPU-friendly optimizations — many shaders include scanline skip (50% pixel reduction), reduced iteration counts, and early-exit patterns
• Shadertoy uniform compatibility — supports time/resolution/mouse and iTime/iResolution/iMouse/iTimeDelta/iFrame/iDate uniforms
• VSync enabled via wglSwapIntervalEXT
• GLSL injection — monitor culling code is transparently injected into shader source at load time by renaming main() and wrapping it. No per-shader modification needed

Usage

shader.exe                    # Run with a random embedded shader
shader.exe terrain.glsl       # Run a specific shader from disk

As a screensaver

1. Build the project (see below)
2. Rename shader.exe to shader.scr, or use the auto-generated copy from build.bat
3. Right-click shader.scr → Install, or copy to C:\Windows\System32
4. Select in Screen Saver Settings

Build

Requirements

• MSVC (Visual Studio Build Tools or full Visual Studio)
• Windows SDK (for rc.exe resource compiler)
• No external libraries — uses only user32, gdi32, opengl32, kernel32

Build command

build.bat

This will:

1. Auto-generate shaders.rc from all *.glsl files in the directory + icon + version info
2. Compile the resource file with rc
3. Compile and link shader.cpp with embedded resources
4. Copy shader.exe to shader.scr
5. Launch shader.exe

Code signing (optional)

sign.bat

Creates a self-signed certificate (first run) and signs both shader.exe and shader.scr using Windows SDK tools (makecert, pvk2pfx, signtool).

Architecture

shader.cpp          Main host — window, OpenGL context, render loop, clock overlay
*.glsl              Fragment shaders (embedded as RCDATA PE resources at build time)
build.bat           Build script — generates .rc, compiles, links
sign.bat            Self-sign script
commodorevic20.ico  Application icon

Shader loading pipeline

1. EnumerateEmbeddedShaders() scans PE resources via EnumResourceNamesA(RT_RCDATA)
2. PickEmbeddedShader() selects one at random using GetTickCount()
3. Source is checked for iDate to decide whether to show the GDI clock overlay
4. If multi-monitor dead zones are detected, InjectCulling() transparently wraps the shader's main() with monitor bounds checking
5. Source is compiled and linked as a fragment shader, paired with a minimal gl_VertexID-based fullscreen quad vertex shader

Multi-monitor culling

On systems with monitors of different sizes or orientations, the virtual screen bounding box contains rectangular gaps where no monitor exists. The host detects this at startup via EnumDisplayMonitors, converts monitor rects to GL coordinates, and injects uniform declarations + a bounds check into each shader's main(). Pixels outside all monitor rects early-return as black — the GPU skips the expensive fragment computation entirely.

This injection is automatic and transparent — no shader modification needed. On uniform monitor setups, no injection occurs (zero overhead).

Tested on

• NVIDIA RTX 3090 + 4 monitors (3 horizontal + 1 vertical)
• Windows 10/11, MSVC 19.44, x64

Shader Credits

Shader	Author	License
aurora.glsl	nimitz 2017 (@stormoid)	CC BY-NC-SA 3.0
cob.glsl	Kabuto, based on @ahnqqq	—
frostedforest.glsl	eiffie	—
gamma.glsl	@XorDev	—
glasscube.glsl	Danil (github.com/danilw)	CC BY-NC-SA 3.0
heaven.glsl	@XorDev	—
matrix.glsl	FabriceNeyret2, otaviogood	—
mountain.glsl	Alexander Alekseev (TDM) 2014	CC BY-NC-SA 3.0
sea.glsl	Alexander Alekseev (TDM) 2014	CC BY-NC-SA 3.0
sinus.glsl	Green120	—
sunset.glsl	srvstr 2025	MIT
terrain.glsl	Inigo Quilez 2014	—
tracks.glsl	Cole Peterson (Plento)	—
tron.glsl	—	—
universe.glsl	Martijn Steinrucken (BigWings) 2018	CC BY-NC-SA 3.0
vorofire.glsl	—	—
warp.glsl	Inigo Quilez 2013	—
wasteland.glsl	Dave Hoskins, nimitz (@stormoid)	CC BY-NC-SA 3.0
waveform.glsl	@XorDev	—
woods.glsl	dr2 2018	CC BY-NC-SA 3.0
zion.glsl	dean_the_coder (@deanthecoder)	CC BY-NC-SA 3.0
7seg.glsl	Based on cmarangu	—

Remaining shaders are twigl.app conversions, Shadertoy ports, or original compositions without embedded attribution.

License

The host code (shader.cpp, build.bat, sign.bat) is released under MIT license.
Individual GLSL shaders retain their original licenses as noted above. Most are CC BY-NC-SA 3.0.
The icon (commodorevic20.ico) is included for personal/non-commercial use.

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psychip.net April 2026