adminandClaude Opus 5.5
ded0022903
Adding up the frame's dt in On update makes anything that counts in steps depend on the frame rate. A pitch sweep sounds a little different on every run. On fixed update runs 60 times per second of game time with dt exactly 1/60, so the same graph gives the same result every time. - fixedSteps in src/core/time.ts is the one rule for the fixed step: spend the frame in steps of 1/60, keep the rest, catch up 8 steps at most after a hitch. - The physics now counts its steps with fixedSteps too. It behaves as before, and On fixed update runs exactly as often as the engine steps. - The steps run after On mouse wheel and before On update, each as a kind of its own with the usual Order setting. - Each step gets its own context, so a node inside that reads dt (Time, Move, Apply force) gets 1/60 rather than the frame. - A paused game has no steps, also for a behavior that runs while paused. - The engine still takes all of a frame's steps before the behaviors run. A force set in On fixed update acts from the next frame on. Tests: - fixed-update.test.ts (new): 5 tests. Step counting, uneven frames adding up to 60 steps a second, the hitch cap, two steps at 30 Hz before On update with dt 1/60 for the event and for Time, one step every other frame at 120 Hz, none while paused. - event-order, node-catalog, physics-system, game-pause: 430 tests together with the new file, all green. - Counter-check: with the frame's dt inside a step and without the pause guard both world tests fail. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
81 lines
2.9 KiB
TypeScript
81 lines
2.9 KiB
TypeScript
/**
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* `On fixed update`: 60 steps a second of game time, each with dt 1/60, however the frames fall –
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* counted by the same rule the physics steps by.
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*/
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import { describe, expect, it } from 'vitest';
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import { SetAssetPropertyCommand } from '../../src/core/commands/assetCommands';
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import { FIXED_STEP, fixedSteps, MAX_FIXED_STEPS } from '../../src/core/time';
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import { graphEditor, makeBehavior, makeSpriteScene, place, startWorld } from '../helpers';
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describe('fixed steps', () => {
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it('spends a frame in steps of 1/60 and keeps the rest for the next', () => {
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expect(fixedSteps(0, FIXED_STEP).steps).toBe(1);
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expect(fixedSteps(0, 1 / 30).steps).toBe(2);
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expect(fixedSteps(0, 0).steps).toBe(0);
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const half = fixedSteps(0, 1 / 120);
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expect(half.steps).toBe(0);
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expect(fixedSteps(half.backlog, 1 / 120).steps).toBe(1);
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});
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it('adds up to the time that passed, however uneven the frames', () => {
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let backlog = 0;
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let steps = 0;
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for (let i = 0; i < 20; i++)
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for (const dt of [0.01, 0.02, 0.005, 0.015]) {
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const next = fixedSteps(backlog, dt);
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backlog = next.backlog;
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steps += next.steps;
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}
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expect(steps).toBe(60);
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});
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it('catches up a hitch only so far and forgets the rest', () => {
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expect(fixedSteps(0, 1)).toEqual({ steps: MAX_FIXED_STEPS, backlog: 0 });
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});
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});
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/** A behavior logging `fixed <dt of the event> <dt a node reads>` per step and `update` per frame. */
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function stepped(runWhilePaused = false) {
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const f = makeSpriteScene('Box');
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const behavior = makeBehavior(f, 'Engine');
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if (runWhilePaused) f.stack.execute(new SetAssetPropertyCommand(behavior.id, 'runWhilePaused', true));
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const edit = graphEditor(f, behavior);
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const fixed = edit.addNode('OnFixedUpdate');
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const eventDt = edit.addNode('Log');
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const nodeDt = edit.addNode('Log');
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const update = edit.addNode('OnUpdate');
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edit.wire([
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[fixed, 'exec', eventDt, 'exec'],
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[fixed, 'dt', eventDt, 'message'],
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[eventDt, 'exec', nodeDt, 'exec'],
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[edit.addNode('Time'), 'dt', nodeDt, 'message'],
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[update, 'exec', edit.addNode('Log', { message: 'update' }), 'exec'],
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]);
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place(f, behavior.id, { x: 0, y: 0 });
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return startWorld(f, { behaviors: true });
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}
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const STEP = String(FIXED_STEP);
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describe('On fixed update', () => {
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it('runs once per 1/60 of game time, before On update, and dt inside is the step', () => {
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const { world, frame } = stepped();
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frame(1 / 30);
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expect(world.log).toEqual([STEP, STEP, STEP, STEP, 'update']);
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world.log.length = 0;
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frame(1 / 120);
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expect(world.log).toEqual(['update']);
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frame(1 / 120);
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expect(world.log).toEqual(['update', STEP, STEP, 'update']);
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});
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it('stands still while the game is paused, also for a behavior that runs then', () => {
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const { world, frame } = stepped(true);
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world.paused = true;
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frame(1 / 30);
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frame(1 / 30);
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expect(world.log).toEqual(['update', 'update']);
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});
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});
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