Shader Lab
Write real GLSL fragment shader code and see it compiled and running live on a 3D mesh — the same shading language WebGL and every modern game engine use under the hood. No server, no sandbox trick — this is a real WebGL shader program.
This Is a Real Fragment Shader
Every pixel covering the mesh runs this exact GLSL code on your GPU, in parallel, once per pixel per frame. vUv is the surface's real texture coordinate and uTime is a genuine running clock uniform — change the math and you're directly programming the GPU's rasterization pipeline.
Fresnel: Why Edges Glow
The Fresnel preset computes the angle between the surface normal and the view direction — grazing angles (like the rim of a sphere) produce a different result than surfaces facing the camera directly, which is the real physical basis for rim lighting and the reason car paint and skin both look brighter at glancing angles.
Errors Show in Your Browser Console
If your GLSL has a syntax error, WebGL's own shader compiler reports the exact line and message — open your browser's DevTools console after clicking Apply to see the real compiler output, honestly, with no fabricated linting layer on top.
Same Language, Real Engines
GLSL (or its close cousins HLSL/MSL) is what Unity, Unreal, Godot, and every WebGL/WebGPU site ultimately compile down to — learning to read this is a real, transferable skill, not a toy syntax invented for this page.