`fwidth()`

Function in Builtins

fwidth(x): abs(dpdx(x)) + abs(dpdy(x)), the screen-space derivative magnitude, component-wise.

import { fwidth } from 'typeshade'

The signature, the description and the examples come from the compiler's own source at commit 26de7be8.

Syntax

const fwidth: <K extends FloatKey>(x: ReadonlyNode<K>) => Node<K>

Parameters

x ReadonlyNode<K>

Return value

Node<K>

Exceptions

SD0109: It exists only on the GPU and only in a fragment shader; the fragment-only-builtin lint rule, which runs at every emit, reports SD0109 when it appears in a vertex or compute stage.

Description

fwidth(x): abs(dpdx(x)) + abs(dpdy(x)), the screen-space derivative magnitude, component-wise. It exists only on the GPU (the CPU evaluation returns 0) and only in a fragment shader; the fragment-only-builtin lint rule, which runs at every emit, reports SD0109 when it appears in a vertex or compute stage. In those stages compute the quantity on the host and pass it in.

Targets

Target	Support	Notes
WGSL (WebGPU)	Supported	`fwidth(x)`.
GLSL ES 3.00 (WebGL2)	Supported	`fwidth(x)`.
CPU oracle	Stub	The oracle has no texture memory and no neighbouring fragments. The call throws unless the module was compiled with `{ gpuStubs: true }`, which returns a placeholder.

In the guide

Source

src/core/ir/node.ts, line 2238, at commit 26de7be8

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