Viewfinder
A shader debugging mod for Iris on Fabric that exposes an HTTP API and in-game commands for external tools and scripts to inspect, test, and automate shader development workflows.
Features
- Shader reload and error list - trigger shader reloads and capture compilation errors
- GPU timing metrics - collect per-pass GPU timing data (collects multiple frames to average out noise)
- Texture dumping - export textures as PNG or raw binary by name (colortex0, or custom texture)
- SSBO buffer dumping - dump shader storage buffer objects to disk for analysis
- Screenshot scheduling - schedule screenshots with configurable frame delay (for PT)
- Patched shader listing - find which patched shader errored programmatically by listing all and searching for "errored"
Installation
- Install Fabric Loader (≥ 0.18.4) for Minecraft 26.1
- Install Fabric API and Iris (which requires Sodium)
- Drop the Viewfinder
.jarinto yourmods/folder
Usage
In-game commands
All commands are registered under /viewfinder:
| Command | Description |
|---|---|
/viewfinder status |
Show current shaderpack name, error count, and API address |
/viewfinder reload |
Reload shaders and report any compilation errors |
/viewfinder errors |
List all captured shader errors |
/viewfinder screenshot [frames] |
Take a screenshot (optionally delayed by N frames) |
/viewfinder screenshot result |
Show the path of the last screenshot |
/viewfinder metrics |
Display per-pass GPU timings |
/viewfinder ssbo list |
List active SSBO buffers |
/viewfinder ssbo dump <index> |
Dump an SSBO buffer to ssbo_dumps/ |
/viewfinder texture list |
List available colortex and custom textures |
/viewfinder texture dump name <name> [raw] |
Dump a texture by name (PNG or raw) |
/viewfinder texture dump id <id> [raw] |
Dump a texture by GL id (PNG or raw) |
/viewfinder patched_shaders |
List Iris patched shader files |
HTTP API
Viewfinder starts an HTTP server on localhost:7150. A full OpenAPI 3.0 spec is available at GET /.
| Method | Endpoint | Description |
|---|---|---|
GET |
/ |
OpenAPI 3.0 specification |
GET |
/status |
Shaderpack status (loaded pack name) |
POST |
/reload |
Reload shaders, returns success and errors |
GET |
/errors |
List captured shader errors |
POST |
/screenshot?frames=N |
Schedule a screenshot (default: next frame) |
GET |
/screenshot/result |
Path to the last saved screenshot |
GET |
/metrics |
GPU timing metrics |
GET |
/list-ssbo |
List active SSBO buffers |
POST |
/ssbo?index=N |
Dump SSBO at given index |
GET |
/list-textures |
List available textures |
POST |
/texture?name=...&raw=bool |
Dump texture by name |
POST |
/texture?id=...&raw=bool |
Dump texture by GL id |
GET |
/patched_shaders |
List patched shader files |
All responses are JSON. Dumped files (textures, SSBOs, screenshots) are written to subdirectories inside the Minecraft game directory.
