Shader Precision Fingerprinting

Shader precision fingerprinting queries the GPU's reported numeric precision for vertex and fragment shaders. Different GPUs report different precision capabilities, making this a reliable hardware-level signal.

How it works

Neoprint calls gl.getShaderPrecisionFormat() for 6 precision types on both vertex and fragment shaders, recording rangeMin, rangeMax, and precision for each.

Queried precision types

Type	Description
LOW_FLOAT	Low-precision floating point
MEDIUM_FLOAT	Medium-precision floating point
HIGH_FLOAT	High-precision floating point
LOW_INT	Low-precision integer
MEDIUM_INT	Medium-precision integer
HIGH_INT	High-precision integer

Each type is queried for both VERTEX_SHADER and FRAGMENT_SHADER, producing 12 data points total (6 types x 2 shader stages).

Why it works

The GPU hardware determines what precision it can support. For example:

• Desktop GPUs typically support full 32-bit float precision across all levels
• Mobile GPUs (Adreno, Mali) may have reduced precision for LOW_FLOAT and MEDIUM_FLOAT
• Integrated GPUs (Intel HD) report different ranges than discrete GPUs (NVIDIA, AMD)

Why it's cross-browser stable

getShaderPrecisionFormat() is a WebGL 1.0 API that queries hardware capabilities directly. The browser engine doesn't influence the reported values — they come from the GPU driver.

Entropy and stability

Property	Value
Entropy	~4 bits
Stability	0.95
Typical duration	<1ms

Very high stability — precision capabilities only change when GPU hardware or drivers change.

Role in crossBrowserId

Included in crossBrowserId as a hardware-dependent signal. Combined with WebGL params and rendering hash, it provides strong GPU identification across browsers.

Usage

const fp = await neoprint.get({ collectors: ['shaderPrecision'] })
const sp = fp.components.shaderPrecision.value

console.log(sp.vertex.highFloat)    // [127, 127, 23]
console.log(sp.fragment.medFloat)   // [14, 14, 10]