typegpu/data/offsets.js

A thin layer between JS and WebGPU/WGSL that improves development experience and allows for faster iteration.

import { Measurer } from 'typed-binary';
import { roundUp } from "../mathUtils.js";
import alignIO from "./alignIO.js";
import { alignmentOf, customAlignmentOf } from "./alignmentOf.js";
import { isUnstruct } from "./dataTypes.js";
import { sizeOf } from "./sizeOf.js";
const cachedOffsets = new WeakMap();
export function offsetsForProps(struct) {
    const cached = cachedOffsets.get(struct);
    if (cached) {
        return cached;
    }
    const measurer = new Measurer();
    const offsets = {};
    let lastEntry;
    for (const key in struct.propTypes) {
        const prop = struct.propTypes[key];
        if (prop === undefined) {
            throw new Error(`Property ${key} is undefined in struct`);
        }
        const beforeAlignment = measurer.size;
        alignIO(measurer, isUnstruct(struct) ? customAlignmentOf(prop) : alignmentOf(prop));
        if (lastEntry) {
            lastEntry.padding = measurer.size - beforeAlignment;
        }
        const propSize = sizeOf(prop);
        offsets[key] = { offset: measurer.size, size: propSize };
        lastEntry = offsets[key];
        measurer.add(propSize);
    }
    if (lastEntry) {
        lastEntry.padding = roundUp(sizeOf(struct), alignmentOf(struct)) - measurer.size;
    }
    cachedOffsets.set(struct, offsets);
    return offsets;
}