threepipe/lib/postprocessing/sortPasses.js

A modern 3D viewer framework built on top of three.js, written in TypeScript, designed to make creating high-quality, modular, and extensible 3D experiences on the web simple and enjoyable.

import { includesAll } from 'ts-browser-helpers';
export function sortPasses(ps) {
    const pipeline = [];
    const dict = {};
    for (const pass of ps) {
        if (!pass.passId)
            continue;
        dict[pass.passId] = {
            after: pass.after ?? [],
            before: pass.before ?? [],
            dependencies: new Set(pass.required ?? []),
        };
    }
    for (const [passId, pass] of Object.entries(dict)) {
        const optional = new Set([...pass.after, ...pass.before]);
        pass.dependencies.forEach(v => optional.has(v) && optional.delete(v));
        optional.forEach(value => {
            const dPass = dict[value];
            if (!dPass)
                return;
            if (dPass.dependencies.has(passId)) {
                console.error('cyclic', passId, value);
                throw 'Encountered cyclic dependency when sorting passes'; // todo better error
            }
            pass.dependencies.add(value);
        });
    }
    // eslint-disable-next-line no-constant-condition
    while (true) {
        let updated = false;
        const entries = [...Object.entries(dict)];
        for (const [passId, pass] of entries) {
            if (pipeline.includes(passId))
                continue;
            if (includesAll(pipeline, pass.dependencies.values())) {
                const afterIndex = Math.max(-1, ...pass.after.map(v => pipeline.indexOf(v)));
                const beforeIndex = Math.min(pipeline.length, ...pass.before.map(v => {
                    const k = pipeline.indexOf(v);
                    return k < 0 ? pipeline.length : k;
                }));
                if (afterIndex >= beforeIndex) {
                    console.error(pass, ps, pipeline, afterIndex, beforeIndex);
                    // throw 'Not possible' // todo better error
                    throw 'Unknown error when sorting passes'; // todo better error
                }
                pipeline.splice(pass.after.length > 0 ? afterIndex + 1 : beforeIndex, 0, passId);
                // console.log(pipeline, passId, afterIndex, beforeIndex)
                updated = true;
                delete dict[passId];
            }
        }
        if (Object.keys(dict).length < 1)
            break;
        if (!updated) {
            console.error(entries, dict, pipeline);
            throw 'Required pass dependency removed unexpectedly'; // when some dependency(required) doesnt exist. todo: show better error.
            break;
        }
    }
    // console.log('Refreshed Pipeline:', pipeline)
    return pipeline;
}
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