`hostFeaturesFor()`

Function in Backends

Translate neutral capability ids into the feature strings one target's host has to activate before it creates a pipeline.

import { hostFeaturesFor } from 'typeshade'

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

Syntax

function hostFeaturesFor(be: Backend, caps: readonly Capability[]): readonly string[]

Parameters

be Backend: the backend whose capability profile does the translating.
caps readonly Capability[]: the neutral ids, usually reflect(m).requiredFeatures.

Return value

readonly string[]

the host-side feature strings, in the order the ids arrived, with the id-less ones dropped.

Description

On WebGL2 those are extension names for gl.getExtension, and on WebGPU they are feature names for requestDevice({ requiredFeatures }).

Feed it reflect(m).requiredFeatures, which reports the ids neutrally because reflection takes a module and never a backend.

It skips every id with no host half. A capability that is core on this target, or one the backend covers by emitting a source directive, contributes nothing. That is why this is a function: a map over the profile at each call site yields undefined holes a host then hands to getExtension verbatim. The returned list has no holes.

Examples

Example

import { hostFeaturesFor, reflect, glslEs300Backend, wgslBackend } from 'typeshade'

const caps = reflect(MODULE).requiredFeatures

for (const ext of hostFeaturesFor(glslEs300Backend, caps)) {
  if (!gl.getExtension(ext)) throw new Error(`WebGL2 lacks ${ext}`)
}

const device = await adapter.requestDevice({
  requiredFeatures: hostFeaturesFor(wgslBackend, caps),
})

In the guide

Capabilities & extensions

Source

src/core/backend.ts, line 143, at commit 26de7be8

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hostFeaturesFor()