@threlte/rapier/dist/lib/createPhysicsStages.js

Components and hooks to use the Rapier physics engine in Threlte

import { useStage, useThrelte } from '@threlte/core';
import { simulationKey, synchronizationKey } from './keys';
export const createPhysicsStages = (framerate, simulationOffset, updateRigidBodySimulationData, options) => {
    let fixedStepTimeAccumulator = 0;
    let simulationTime = 0;
    let lastSimulationTime = 0;
    const { renderStage } = useThrelte();
    const simulationStage = useStage(simulationKey, {
        after: options?.simulationStageOptions?.after,
        before: options?.simulationStageOptions?.before,
        callback(delta, runTasks) {
            if (framerate.current === 'varying') {
                runTasks();
            }
            else {
                const rate = 1 / framerate.current;
                simulationTime += delta;
                fixedStepTimeAccumulator += delta;
                const iterations = Math.ceil(fixedStepTimeAccumulator / rate);
                for (let iteration = 0; iteration < iterations; iteration++) {
                    updateRigidBodySimulationData.set(iteration >= iterations - 2);
                    runTasks(rate);
                    fixedStepTimeAccumulator -= rate;
                    lastSimulationTime += rate;
                }
                simulationOffset.set((simulationTime - lastSimulationTime) / rate + 1);
            }
        }
    });
    const synchronizationStage = useStage(synchronizationKey, {
        after: options?.synchronizationStageOptions?.after
            ? Array.isArray(options.synchronizationStageOptions.after)
                ? [...options.synchronizationStageOptions.after, simulationKey]
                : [options.synchronizationStageOptions.after, simulationKey]
            : simulationKey,
        before: options?.synchronizationStageOptions?.before
            ? Array.isArray(options.synchronizationStageOptions.before)
                ? [...options.synchronizationStageOptions.before, renderStage]
                : [options.synchronizationStageOptions.before, renderStage]
            : renderStage
    });
    return { simulationStage, synchronizationStage };
};