Let a game hand values to the parameters of a sound FX #311

A sound FX played the same every time: its numbers were settings of
the nodes. Now the Input declares parameters with a default, every
number of Gain, Pitch and EQ is an input they can feed, and a Play
sound hands in values for them.

- Input declares number parameters in the inspector, each with a
  Default (DeclaredPort.default, SetPortDefaultCommand). They are
  outputs of the Input. Input and Output count as terminals now, one
  of each per graph.
- Gain, Pitch and EQ take their numbers at inputs under the keys the
  settings had, so saved graphs sound as before without a migration.
  Each value is held to its range however it arrives.
- The compiler gives an FxPlan with the parameters still open.
  fxChainOf fills them in when a voice starts. The player still only
  sees an FxChain.
- New behavior node Sound FX parameters: names an FX and picks its
  parameters like a Variables node picks variables. Each picked one is
  a number input that starts at the FX's default. Its output has the
  new port type fxparams, which only fits Play sound's fx params.
- Play sound warns when the parameters name another FX than the one
  it plays. Names the FX does not know are left out.
- Renaming a parameter at the Input renames it in every Sound FX
  parameters node naming that FX, edges and values included.
- The Sound FX tab has a number field per parameter in its header.
  Play uses those values, they are never written into the asset.
- A value counts from the start of a voice. Changing a playing voice
  is #315, a Mix node is #316.

Tests:
- soundfx.test.ts 22 (+11): parameters in the plan, held values, a
  0-by-default stage, EQ band, save with defaults, wrong port types,
  default command with undo, Sound FX parameters into Play sound,
  defaults of picked ones, node problems, mismatch, rename with undo
- node-catalog 368 (+3): Play sound fx params, Sound FX parameters
- e2e 34: ALL PASSED - 28 checks (+2: header field plays depth 5,
  a Sound FX parameters node gives the game's voice depth 7)
- Gate on melektaus-atx: typecheck, lint, prettier clean, 240 test
  files, 3636 tests green
- Counter-check: with fxChainOf ignoring the values and the rename
  not followed, 5 of the new tests fail.
- Browser probe: header fields, inspector Default and the picked
  parameter looked at in two screenshots.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/core/commands/portCommands.ts

@@ -1,6 +1,7 @@
 import {
   BEHAVIOR_PARAM,
   declaresPropertyPorts,
+  declaresSoundFxPorts,
   declaresVariablePorts,
   type DeclaredPort,
   findNode,
@@ -17,6 +18,8 @@ import {
   OBJECT_BEHAVIOR_PARAM,
   propertyTargetOf,
   SHADER_CALL,
+  SOUND_FX_INPUT,
+  soundFxSourceOf,
   variablesSourceOf,
 } from '../graph';
 import { isGraphAsset } from '../model/Asset';
@@ -342,6 +345,54 @@ export class RenamePortCommand extends RenameCommand {
     if (ports.some((p) => p.key === to)) throw new CommandError(`"${to}" already exists`);
     node.ports = ports.map((p) => (p.key === from ? { ...p, key: to } : p));
     for (const site of sites) carryPort(site, from, to);
+    if (node.type === SOUND_FX_INPUT) renameSoundFxParamPorts(project, this.assetId, from, to);
+  }
+}
+
+/** The default of a sound FX parameter (#311): what it is wherever no `Play sound` hands a value in. */
+export class SetPortDefaultCommand implements Command {
+  readonly label: string;
+  private was: number | undefined;
+
+  constructor(
+    private readonly assetId: string,
+    private readonly nodeId: string,
+    private readonly key: string,
+    private readonly value: number,
+  ) {
+    this.label = `Set default of ${key}`;
+  }
+
+  execute(project: Project): void {
+    const node = requireNode(project, this.assetId, this.nodeId);
+    if (node.type !== SOUND_FX_INPUT) throw new CommandError('Only a sound FX Input has defaults');
+    const port = (node.ports ?? []).find((p) => p.key === this.key);
+    if (!port) throw new CommandError(`Port "${this.key}" not found`);
+    if (!Number.isFinite(this.value)) throw new CommandError('A default is a number');
+    this.was = port.default;
+    this.mark(node, this.value);
+  }
+
+  undo(project: Project): void {
+    this.mark(requireNode(project, this.assetId, this.nodeId), this.was);
+  }
+
+  private mark(node: GraphNode, value: number | undefined): void {
+    node.ports = (node.ports ?? []).map((port) => {
+      if (port.key !== this.key) return port;
+      const { default: _, ...plain } = port;
+      return value === undefined ? plain : { ...plain, default: value };
+    });
+  }
+}
+
+/** A renamed parameter of a sound FX, followed into every node that sets it. */
+function renameSoundFxParamPorts(project: Project, fxId: string, from: string, to: string): void {
+  for (const asset of project.assets) {
+    if (!isGraphAsset(asset)) continue;
+    for (const node of asset.graph.nodes)
+      if (declaresSoundFxPorts(node.type) && soundFxSourceOf(node.params) === fxId)
+        renamePortOn(asset.graph, node, from, to);
   }
 }
 

src/core/graph/Graph.ts

@@ -6,7 +6,8 @@ export type { DeclaredPortKind } from '../properties/kinds';
 /**
  * `exec` carries control flow, the others values; `any` accepts every value type. `vec3` is a
  * colour inside a shader graph, where the values are GLSL and no behavior node ever sees one;
- * `picture` is what a shader's Pass draws (#301), for the nodes that read a picture.
+ * `picture` is what a shader's Pass draws (#301), for the nodes that read a picture. `fxparams` is
+ * the values a `Play sound` hands to the parameters of its sound FX (#311).
  */
 export type PortType =
   | 'exec'
@@ -19,6 +20,7 @@ export type PortType =
   | 'vec3'
   | 'picture'
   | 'audio'
+  | 'fxparams'
   | 'any';
 
 export interface PortRef {
@@ -70,6 +72,8 @@ export interface DeclaredPort {
    * from it. On a start node, a node running the behavior has it picked in advance as well.
    */
   machine?: string;
+  /** On a parameter of a sound FX Input: its value wherever nobody hands one in (#311). */
+  default?: number;
 }
 
 export function declaredPortType(kind: DeclaredPortKind): PortType {
@@ -183,12 +187,14 @@ export function graphFingerprint(graph: Graph): string {
 /**
  * A number may feed a colour: the shader compiler spreads it over the three channels. A picture is
  * no value a calculation could take, so like `exec` it goes only where a picture is read – and a
- * sound on its way through effects (#311) only where a sound goes in.
+ * sound on its way through effects (#311) only where a sound goes in, and its parameters only to a
+ * `Play sound`.
  */
 export function portsCompatible(from: PortType, to: PortType): boolean {
   if (from === 'exec' || to === 'exec') return from === to;
   if (from === 'picture' || to === 'picture') return from === to;
   if (from === 'audio' || to === 'audio') return from === to;
+  if (from === 'fxparams' || to === 'fxparams') return from === to;
   if (from === 'number' && to === 'vec3') return true;
   return from === to || from === 'any' || to === 'any';
 }

src/core/graph/NodeContext.ts

@@ -1,6 +1,7 @@
 import type { AnimationPlayer } from '../model/animation';
 import type { Mat } from '../model/matrix';
 import type { Position, PropertyBag } from '../model/Properties';
+import type { FxParams } from '../soundfx/nodes';
 import { type ChainTransform, composeAlongChain } from '../model/walk';
 import { enabledAlongChain } from '../properties/enabled';
 import { localMatrixOf, positionOf, transformOf } from '../properties/transform';
@@ -238,8 +239,16 @@ export interface NodeContext {
    * a sound is something a thing in the world is doing. `detached` gives that up on purpose, for
    * the one case where the rule is in the way: the death sound of an object that destroys itself.
    * `fx` names a sound FX asset the voice is played through (#311); `''` plays it as it is.
+   * `fxParams` are values for its parameters; one not given is the default the FX declares.
    */
-  playSound(assetId: string, volume: number, loop: boolean | undefined, detached: boolean, fx: string): void;
+  playSound(
+    assetId: string,
+    volume: number,
+    loop: boolean | undefined,
+    detached: boolean,
+    fx: string,
+    fxParams: FxParams,
+  ): void;
   /** Silences every voice of that sound; `''` silences everything this run started. */
   stopSound(assetId: string): void;
   /**

src/core/graph/NodeRegistry.ts

@@ -213,7 +213,8 @@ function isInlinePort(port: PortDef): boolean {
     port.type !== 'object' &&
     port.type !== 'struct' &&
     port.type !== 'picture' &&
-    port.type !== 'audio'
+    port.type !== 'audio' &&
+    port.type !== 'fxparams'
   );
 }
 

src/core/graph/lookup.ts

@@ -1,7 +1,7 @@
 import type { AnimationClip } from '../model/animation';
 import type { VectorPoint } from '../model/Asset';
 import type { PropertyBag } from '../model/Properties';
-import type { Graph } from './Graph';
+import type { DeclaredPort, Graph } from './Graph';
 
 /** What running another behavior's graph in place needs: its nodes, its variable defaults, its name. */
 export interface BehaviorProgram {
@@ -17,6 +17,12 @@ export interface ShaderFunction {
   graph: Graph;
 }
 
+/** A sound FX as a node naming it sees it: the parameters its Input declares (#311). */
+export interface SoundFxShape {
+  name: string;
+  params: readonly DeclaredPort[];
+}
+
 /** One state of a machine: the node id is what a port and the runtime hold, the name is the label. */
 export interface MachineState {
   id: string;
@@ -52,6 +58,7 @@ export interface GraphLookup {
   behavior(assetId: string): BehaviorProgram | null;
   /** A shader function's graph, which a call node takes its ports from and the compiler sets in (#303). */
   shaderFunction(assetId: string): ShaderFunction | null;
+  soundFx(assetId: string): SoundFxShape | null;
   machine(assetId: string): StateMachine | null;
   curve(assetId: string): readonly VectorPoint[] | null;
   /** A Struct asset as a run knows it: a name and field names, nothing else travels (#254). */
@@ -90,6 +97,7 @@ export interface ValueTyping {
 export const NO_LOOKUP: GraphLookup = {
   behavior: () => null,
   shaderFunction: () => null,
+  soundFx: () => null,
   machine: () => null,
   curve: () => null,
   structType: () => null,

src/core/graph/nested.ts

@@ -28,10 +28,29 @@ const ON_START = 'OnStart';
 export const SHADER_FUNCTION_INPUT = 'ShaderFunctionInput';
 export const SHADER_FUNCTION_OUTPUT = 'ShaderFunctionOutput';
 export const SHADER_CALL = 'ShaderCall';
+/** The two ends of a sound FX graph and the behavior node naming its parameters (#311). */
+export const SOUND_FX_INPUT = 'SoundFxInput';
+export const SOUND_FX_OUTPUT = 'SoundFxOutput';
+export const SOUND_FX_PARAMETERS = 'SoundFxParameters';
+const PLAY_SOUND = 'PlaySound';
 
 export const BEHAVIOR_PARAM = 'behavior';
 export const FUNCTION_PARAM = 'function';
 export const VARIABLES_PARAM = 'variablesAsset';
+export const SOUND_FX_PARAM = 'soundFxAsset';
+
+/** Whose parameters a `Sound FX parameters` node sets. */
+export const SOUND_FX_SETTING: PropertyDef = {
+  key: SOUND_FX_PARAM,
+  label: 'Sound FX',
+  kind: 'asset',
+  default: '',
+  assetTypes: ['soundfx'],
+};
+
+export function soundFxSourceOf(params: PropertyBag): string {
+  return textOf(params[SOUND_FX_PARAM] ?? '');
+}
 
 /** Whose declarations a `Variables` node reads; empty is the behavior the node sits in. */
 export const VARIABLES_SETTING: PropertyDef = {
@@ -71,6 +90,11 @@ export function declaresPropertyPorts(type: string): boolean {
   return type === PROPERTIES;
 }
 
+/** Nodes whose declared ports are parameters of the sound FX they name. */
+export function declaresSoundFxPorts(type: string): boolean {
+  return type === SOUND_FX_PARAMETERS;
+}
+
 /** Identifier-like, and not `exec`: that key belongs to the fixed flow port of every terminal node. */
 export function isValidPortName(name: string): boolean {
   return isValidFieldName(name) && name !== 'exec';
@@ -127,13 +151,15 @@ export function isTerminalType(type: string): boolean {
     type === BEHAVIOR_START ||
     type === BEHAVIOR_END ||
     type === SHADER_FUNCTION_INPUT ||
-    type === SHADER_FUNCTION_OUTPUT
+    type === SHADER_FUNCTION_OUTPUT ||
+    type === SOUND_FX_INPUT ||
+    type === SOUND_FX_OUTPUT
   );
 }
 
 /** The terminal whose ports a caller passes in, rather than takes out. */
 export function isEntryTerminal(type: string): boolean {
-  return type === BEHAVIOR_START || type === SHADER_FUNCTION_INPUT;
+  return type === BEHAVIOR_START || type === SHADER_FUNCTION_INPUT || type === SOUND_FX_INPUT;
 }
 
 export function isTerminalNode(node: GraphNode): boolean {
@@ -354,6 +380,7 @@ export function ghostProblem(node: GraphNode, graph: Graph, def: NodeDef): strin
 export function callProblem(node: GraphNode, lookup: GraphLookup, ownerId = ''): string | null {
   if (node.type === ON_BEHAVIOR) return listenProblem(node, lookup, ownerId);
   if (node.type === SHADER_CALL) return functionCallProblem(node, lookup, ownerId);
+  if (node.type === SOUND_FX_PARAMETERS) return soundFxParametersProblem(node, lookup);
   if (node.type !== RUN_BEHAVIOR) return lerpProblem(node, lookup);
   const id = textOf(node.params[BEHAVIOR_PARAM] ?? '');
   if (!id) return 'No behavior picked';
@@ -398,6 +425,27 @@ function functionCallProblem(node: GraphNode, lookup: GraphLookup, ownerId: stri
   return null;
 }
 
+function soundFxParametersProblem(node: GraphNode, lookup: GraphLookup): string | null {
+  const id = soundFxSourceOf(node.params);
+  if (!id) return 'No sound FX picked';
+  return lookup.soundFx(id) ? null : 'That sound FX is gone';
+}
+
+/**
+ * A `Play sound` whose parameters come from a node naming another sound FX than the one it plays:
+ * the names that FX does not know are left out, so the values would go nowhere. Only said where both
+ * are picked in place – one coming over an edge may be either.
+ */
+export function soundFxParamsMismatch(node: GraphNode, graph: Graph): string | null {
+  if (node.type !== PLAY_SOUND || edgesInto(graph, node.id, 'fx').length > 0) return null;
+  const played = textOf(node.params.fx ?? '');
+  const edge = edgesInto(graph, node.id, 'fxParams')[0];
+  const from = edge && findNode(graph, edge.from.node);
+  if (!played || from?.type !== SOUND_FX_PARAMETERS) return null;
+  const named = soundFxSourceOf(from.params);
+  return named && named !== played ? 'The parameters are for another sound FX' : null;
+}
+
 /** The ids the nodes of one type in that graph name in `param`, picked or not found alike. */
 function namedBy(graph: Graph, type: string, param: string): string[] {
   return graph.nodes

src/core/graph/nodes/action/PlaySound.ts

@@ -1,3 +1,5 @@
+import { isStruct } from '../../../model/Properties';
+import type { FxParams } from '../../../soundfx/nodes';
 import type { NodeDef, PortDef } from '../../NodeRegistry';
 import { asBoolean, asNumber, asString, type Value } from '../../values';
 import { exec, num, soundFxPort, soundPort, withDefault } from '../shared';
@@ -56,8 +58,17 @@ export const PlaySound: NodeDef = {
     "leaves the asset's own setting alone or overrules it, so the asset says what the sound is and " +
     'the node only colors it. Each play is a voice of its own: firing this twice in a row is heard ' +
     'twice, overlapping. The sound belongs to this object and stops when the object is destroyed, ' +
-    'unless "detached" is on. "fx" sends it through a sound FX asset; left empty, it plays as it is.',
-  inputs: [exec(), soundPort(), withDefault(num('volume'), 1), loopPort(), detachedPort(), soundFxPort()],
+    'unless "detached" is on. "fx" sends it through a sound FX asset; left empty, it plays as it is. ' +
+    '"fx params" takes values for its parameters from a Sound FX parameters node.',
+  inputs: [
+    exec(),
+    soundPort(),
+    withDefault(num('volume'), 1),
+    loopPort(),
+    detachedPort(),
+    soundFxPort(),
+    { key: 'fxParams', label: 'fx params', type: 'fxparams' },
+  ],
   outputs: [exec()],
   params: [],
   run: (ctx, inputs) => {
@@ -69,7 +80,16 @@ export const PlaySound: NodeDef = {
         loopChoice(inputs.loop),
         asBoolean(inputs.detached),
         asString(inputs.fx),
+        fxParamsOf(inputs.fxParams),
       );
     return { next: 'exec' };
   },
 };
+
+/** The numbers of a parameter bundle; anything else hands in none. */
+function fxParamsOf(value: Value | undefined): FxParams {
+  if (!isStruct(value)) return {};
+  const params: Record<string, number> = {};
+  for (const [key, item] of Object.entries(value)) if (typeof item === 'number') params[key] = item;
+  return params;
+}

src/core/graph/nodes/data/SoundFxParameters.ts

@@ -0,0 +1,37 @@
+import type { StructValue } from '../../../model/Properties';
+import { SOUND_FX_PARAMETERS, SOUND_FX_SETTING, soundFxSourceOf } from '../../nested';
+import type { NodeDef } from '../../NodeRegistry';
+import { asNumber } from '../../values';
+
+/**
+ * Values for the parameters of one sound FX (#311), picked from those its Input declares the way a
+ * Variables node picks variables. Each picked one is a number input starting at the FX's default;
+ * the bundle goes into the `fx params` input of a `Play sound`.
+ */
+export const SoundFxParameters: NodeDef = {
+  type: SOUND_FX_PARAMETERS,
+  label: 'Sound FX parameters',
+  category: 'data',
+  description:
+    'Values for the parameters of a sound FX, for the "fx params" input of a Play sound. Pick the parameters to set; one not picked keeps the default its Input gives it.',
+  inputs: [],
+  outputs: [{ key: 'params', label: 'params', type: 'fxparams' }],
+  params: [SOUND_FX_SETTING],
+  declaresPorts: 'inputs',
+  portKinds: ['number'],
+  declaredPort: (port, node, _graph, lookup) => {
+    const declared = lookup.soundFx(soundFxSourceOf(node.params))?.params.find((p) => p.key === port.key);
+    const value = declared?.default ?? 0;
+    return {
+      key: port.key,
+      label: port.key,
+      type: 'number',
+      default: value,
+      field: { key: port.key, label: port.key, kind: 'number', default: value },
+    };
+  },
+  run: (_ctx, inputs, _params, def) => {
+    const values: StructValue = Object.fromEntries(def.inputs.map((p) => [p.key, asNumber(inputs[p.key])]));
+    return { outputs: { params: values } };
+  },
+};

src/core/graph/nodes/index.ts

@@ -89,6 +89,7 @@ import { Or } from './data/Or';
 import { Owner } from './data/Owner';
 import { PackStruct } from './data/PackStruct';
 import { Properties } from './data/Properties';
+import { SoundFxParameters } from './data/SoundFxParameters';
 import { Parent } from './data/Parent';
 import { Random } from './data/Random';
 import { RenderLayerOf } from './data/RenderLayerOf';
@@ -297,6 +298,7 @@ export const BUILT_IN_NODES: readonly NodeDef[] = [
   StopAnimation,
   PlaySound,
   StopSound,
+  SoundFxParameters,
   LoadScene,
   Log,
   StopGame,

src/core/model/graphLookup.ts

@@ -1,4 +1,5 @@
 import type { GraphLookup } from '../graph/lookup';
+import { SOUND_FX_INPUT, terminalNode } from '../graph/nested';
 import { startStateOf, statesOf, transitionsOf } from '../graph/stateMachine';
 import { pictureSize } from '../properties/aspect';
 import { resolveAssetProps } from '../properties/resolve';
@@ -34,6 +35,12 @@ export function graphLookup(project: Project): GraphLookup {
       };
     },
     shaderFunction: shaderFunctionsOf(project),
+    soundFx: (assetId) => {
+      const asset = findAssetOf(project, assetId, 'soundfx');
+      return asset
+        ? { name: asset.name, params: terminalNode(asset.graph, SOUND_FX_INPUT)?.ports ?? [] }
+        : null;
+    },
     machine: (assetId) => {
       const asset = findAssetOf(project, assetId, 'statemachine');
       if (!asset) return null;

src/core/soundfx/compile.ts

@@ -1,10 +1,13 @@
 import { graphEmitter } from '../graph/emitGraph';
-import { type Graph, graphFingerprint } from '../graph/Graph';
+import { type DeclaredPort, type Graph, graphFingerprint, type GraphNode } from '../graph/Graph';
+import { terminalNode } from '../graph/nested';
+import { inlineValue, nodeDef } from '../graph/NodeRegistry';
+import { asNumber } from '../graph/values';
 import type { SoundFxAsset } from '../model/Asset';
-import { nodeDef } from '../graph/NodeRegistry';
 import {
-  DRY,
-  type FxChain,
+  EMPTY_PLAN,
+  type FxAmount,
+  type FxPlan,
   isSoundFxNodeDef,
   SOUND_FX_INPUT,
   SOUND_FX_OUTPUT,
@@ -13,7 +16,7 @@ import {
 
 export interface SoundFxBuild {
   /** Null while the graph has a problem – a sound played through it is then played dry. */
-  compiled: FxChain | null;
+  compiled: FxPlan | null;
   /** How many nodes between Input and Output the sound passes. */
   effects: number;
   /** Per node id, what keeps the graph from compiling. */
@@ -22,33 +25,64 @@ export interface SoundFxBuild {
   reason: string;
 }
 
+/** What travels along an edge of a sound FX graph: the sound so far, or a number. */
+type FxValue = { plan: FxPlan } | { amount: FxAmount };
+
+/** The parameters the Input declares, in their order, each with its default. */
+export function soundFxParams(graph: Graph): readonly DeclaredPort[] {
+  return terminalNode(graph, SOUND_FX_INPUT)?.ports ?? [];
+}
+
+function inputOutputs(node: GraphNode): Record<string, FxValue> {
+  const outputs: Record<string, FxValue> = { out: { plan: EMPTY_PLAN } };
+  for (const port of node.ports ?? [])
+    outputs[port.key] = { amount: { value: port.default ?? 0, param: port.key } };
+  return outputs;
+}
+
 /**
  * A sound FX graph to the line a voice is sent along: walked back from the Output to the Input, every
  * node on the way adding what it does. An input takes one edge, so the line never forks on its way
- * to the Output; a node fed from nowhere is a problem rather than silence.
+ * to the Output; a node fed from nowhere is a problem rather than silence. A number fed from a
+ * parameter stays open in the plan until a voice is started (#311).
  */
 export function compileSoundFx(graph: Graph): SoundFxBuild {
-  const walk = graphEmitter<SoundFxNodeDef, FxChain>(graph, {
+  const walk = graphEmitter<SoundFxNodeDef, FxValue>(graph, {
     isDef: isSoundFxNodeDef,
     noun: 'sound FX',
-    // Only reached with every input fed, so whatever is not the Input has its sound arriving.
-    emit: (def, inputs, node) => ({ out: def.emit(inputs.in ?? DRY, node.params) }),
-    unfed: (node) => {
+    emit: (def, inputs, node) => {
+      if (node.type === SOUND_FX_INPUT) return inputOutputs(node);
+      const amounts: Record<string, FxAmount> = {};
+      for (const [key, value] of Object.entries(inputs)) if ('amount' in value) amounts[key] = value.amount;
+      const arriving = inputs.in;
+      const plan = arriving && 'plan' in arriving ? arriving.plan : EMPTY_PLAN;
+      return { out: { plan: def.emit(plan, amounts) } };
+    },
+    unfed: (node, port) => {
+      if (port.type === 'number') return { amount: { value: asNumber(inlineValue(node, port)) } };
       walk.problem(node, 'Nothing comes in: connect it to the Input');
       return null;
     },
+    conform: (node, port, value) => {
+      if ((port.type === 'audio') === 'plan' in value) return value;
+      walk.problem(
+        node,
+        port.type === 'audio' ? `"${port.label}" takes a sound` : `"${port.label}" takes a number`,
+      );
+      return null;
+    },
   });
 
   const output = graph.nodes.find((n) => n.type === SOUND_FX_OUTPUT);
   if (!output) return { compiled: null, effects: 0, problems: walk.problems, reason: 'No Output node' };
-  const chain = walk.input(output, nodeDef(SOUND_FX_OUTPUT)!.inputs[0]!);
+  const arrived = walk.input(output, nodeDef(SOUND_FX_OUTPUT)!.inputs[0]!);
   const failed = walk.firstProblem();
-  if (failed !== null || !chain)
+  if (failed !== null || !arrived || !('plan' in arrived))
     return { compiled: null, effects: 0, problems: walk.problems, reason: failed ?? 'Cannot compile' };
   const effects = graph.nodes.filter(
     (n) => walk.reached(n) && n.type !== SOUND_FX_INPUT && n.type !== SOUND_FX_OUTPUT,
   ).length;
-  return { compiled: chain, effects, problems: walk.problems, reason: '' };
+  return { compiled: arrived.plan, effects, problems: walk.problems, reason: '' };
 }
 
 const builds = new Map<string, { fingerprint: string; build: SoundFxBuild }>();

src/core/soundfx/nodes.ts

@@ -1,7 +1,10 @@
+import type { DeclaredPort } from '../graph/Graph';
+import { SOUND_FX_INPUT, SOUND_FX_OUTPUT } from '../graph/nested';
 import type { NodeDef, PortDef } from '../graph/NodeRegistry';
-import type { PropertyBag } from '../model/Properties';
 import type { FlatDef } from '../properties/PropertySchema';
 
+export { SOUND_FX_INPUT, SOUND_FX_OUTPUT };
+
 /** The filter shapes the EQ uses – Web Audio's names, so the player hands them on as they are. */
 export type FxFilter = 'lowshelf' | 'peaking' | 'highshelf';
 
@@ -21,45 +24,92 @@ export interface FxChain {
 
 export const DRY: FxChain = { pitch: 0, stages: [] };
 
+/**
+ * A number of the graph as the compiler knows it: typed in, or a parameter of the Input that a
+ * `Play sound` may hand a value for (#311). `value` is what it is otherwise, and a parameter is held
+ * to the row it ends in only once its value is known.
+ */
+export interface FxAmount {
+  value: number;
+  param?: string;
+  min?: number;
+  max?: number;
+}
+
+export type FxStagePlan =
+  | { kind: 'gain'; db: FxAmount }
+  | { kind: 'filter'; filter: FxFilter; frequency: number; gain: FxAmount; q: number };
+
+/** A chain with its parameters still open: compiled once, filled in for every voice by `fxChainOf`. */
+export interface FxPlan {
+  pitch: readonly FxAmount[];
+  stages: readonly FxStagePlan[];
+}
+
+export const EMPTY_PLAN: FxPlan = { pitch: [], stages: [] };
+
+/** Values for the parameters, by name; a name the plan does not have is left out. */
+export type FxParams = Readonly<Record<string, number>>;
+
 /**
  * A node of a sound FX graph (#311). It never runs: `emit` says what it does to the sound arriving
- * at its one input. Input and Output have a side less and no effect of their own.
+ * at its one audio input, given the numbers at its other inputs. Input and Output have no effect.
  */
 export interface SoundFxNodeDef extends NodeDef {
   category: 'sound';
-  emit(chain: FxChain, params: PropertyBag): FxChain;
+  emit(plan: FxPlan, amounts: Readonly<Record<string, FxAmount>>): FxPlan;
 }
 
 export function isSoundFxNodeDef(def: NodeDef): def is SoundFxNodeDef {
   return def.category === 'sound' && 'emit' in def;
 }
 
-export const SOUND_FX_INPUT = 'SoundFxInput';
-export const SOUND_FX_OUTPUT = 'SoundFxOutput';
-
 const audioIn: PortDef = { key: 'in', label: 'in', type: 'audio' };
 const audioOut: PortDef = { key: 'out', label: 'out', type: 'audio' };
 
-function numberParam(key: string, label: string, min: number, max: number, step: number): FlatDef<'number'> {
+function numberRow(key: string, label: string, min: number, max: number, step: number): FlatDef<'number'> {
   return { key, label, kind: 'number', default: 0, min, max, step };
 }
 
-/** A param's value held to its row, so a hand-edited project cannot blow a speaker. */
-function read(params: PropertyBag, def: FlatDef<'number'>): number {
-  const value = Number(params[def.key] ?? def.default);
-  if (!Number.isFinite(value)) return def.default;
-  return Math.max(def.min ?? -Infinity, Math.min(def.max ?? Infinity, value));
+/** An input taking a number: typed in under the key the setting had, or fed from a parameter. */
+function numberIn(row: FlatDef<'number'>): PortDef {
+  return { key: row.key, label: row.label, type: 'number', field: row };
+}
+
+function holdTo(value: number, row: FlatDef<'number'>): number {
+  if (!Number.isFinite(value)) return row.default;
+  return Math.max(row.min ?? -Infinity, Math.min(row.max ?? Infinity, value));
+}
+
+/** The amount at an input, held to its row, so a hand-edited project cannot blow a speaker. */
+function held(amount: FxAmount | undefined, row: FlatDef<'number'>): FxAmount {
+  if (!amount) return { value: row.default };
+  const value = holdTo(amount.value, row);
+  if (amount.param === undefined) return { value };
+  return { value, param: amount.param, min: row.min, max: row.max };
+}
+
+/** Whether an amount does nothing however the sound is played: a typed-in 0. */
+const isNone = (amount: FxAmount) => amount.param === undefined && amount.value === 0;
+
+/** A parameter of the Input as the nodes it feeds see it. */
+export function soundFxParamPort(port: DeclaredPort): PortDef {
+  return { key: port.key, label: port.key, type: 'number' };
 }
 
 export const SoundFxInput: SoundFxNodeDef = {
   type: SOUND_FX_INPUT,
   label: 'Input',
   category: 'sound',
-  description: 'The sound as the Play sound node starts it, before any effect.',
+  description:
+    'The sound as the Play sound node starts it, before any effect. Every parameter declared here is a number output with a default; a Play sound can hand in other values through a Sound FX parameters node.',
   inputs: [],
   outputs: [audioOut],
   params: [],
-  emit: (chain) => chain,
+  declaresPorts: 'outputs',
+  portKinds: ['number'],
+  declaredPort: (port) => soundFxParamPort(port),
+  emit: (plan) => plan,
 };
 
 export const SoundFxOutput: SoundFxNodeDef = {
@@ -70,10 +120,10 @@ export const SoundFxOutput: SoundFxNodeDef = {
   inputs: [audioIn],
   outputs: [],
   params: [],
-  emit: (chain) => chain,
+  emit: (plan) => plan,
 };
 
-const GAIN = numberParam('gain', 'Gain (dB)', -60, 24, 0.5);
+const GAIN = numberRow('gain', 'Gain (dB)', -60, 24, 0.5);
 
 export const SoundFxGain: SoundFxNodeDef = {
   type: 'SoundFxGain',
@@ -81,17 +131,16 @@ export const SoundFxGain: SoundFxNodeDef = {
   category: 'sound',
   description:
     'Makes the sound louder or quieter, in decibels: 0 leaves it as it is, -6 is about half as loud, +6 twice. Above 0 it can clip.',
-  inputs: [audioIn],
+  inputs: [audioIn, numberIn(GAIN)],
   outputs: [audioOut],
-  params: [GAIN],
-  emit: (chain, params) => {
-    const db = read(params, GAIN);
-    if (db === 0) return chain;
-    return { ...chain, stages: [...chain.stages, { kind: 'gain', gain: 10 ** (db / 20) }] };
+  params: [],
+  emit: (plan, amounts) => {
+    const db = held(amounts.gain, GAIN);
+    return isNone(db) ? plan : { ...plan, stages: [...plan.stages, { kind: 'gain', db }] };
   },
 };
 
-const SEMITONES = numberParam('semitones', 'Semitones', -24, 24, 1);
+const SEMITONES = numberRow('semitones', 'Semitones', -24, 24, 1);
 
 export const SoundFxPitch: SoundFxNodeDef = {
   type: 'SoundFxPitch',
@@ -99,10 +148,13 @@ export const SoundFxPitch: SoundFxNodeDef = {
   category: 'sound',
   description:
     'Plays the sound higher or lower, in semitones: 12 is an octave up. It is the speed the sound is played at, so a higher one is also shorter, and it applies to the whole sound wherever the node sits in the line.',
-  inputs: [audioIn],
+  inputs: [audioIn, numberIn(SEMITONES)],
   outputs: [audioOut],
-  params: [SEMITONES],
-  emit: (chain, params) => ({ ...chain, pitch: chain.pitch + read(params, SEMITONES) }),
+  params: [],
+  emit: (plan, amounts) => {
+    const semitones = held(amounts.semitones, SEMITONES);
+    return isNone(semitones) ? plan : { ...plan, pitch: [...plan.pitch, semitones] };
+  },
 };
 
 /** The five bands of the EQ: a shelf at either end and three peaks between them. */
@@ -116,7 +168,7 @@ export const EQ_BANDS: readonly { key: string; label: string; filter: FxFilter;
 
 /** About an octave and a half wide: neighbouring peaks overlap, so no frequency falls between them. */
 const PEAK_Q = 1;
-const EQ_PARAMS = EQ_BANDS.map((band) => numberParam(band.key, band.label, -24, 24, 0.5));
+const EQ_ROWS = EQ_BANDS.map((band) => numberRow(band.key, band.label, -24, 24, 0.5));
 
 export const SoundFxEq: SoundFxNodeDef = {
   type: 'SoundFxEq',
@@ -124,17 +176,17 @@ export const SoundFxEq: SoundFxNodeDef = {
   category: 'sound',
   description:
     'A five-band equalizer: raises or lowers the lows (80 Hz), low mids (250 Hz), mids (1 kHz), high mids (4 kHz) and highs (12 kHz), each in decibels. A band at 0 does nothing.',
-  inputs: [audioIn],
+  inputs: [audioIn, ...EQ_ROWS.map(numberIn)],
   outputs: [audioOut],
-  params: EQ_PARAMS,
-  emit: (chain, params) => {
-    const stages: FxStage[] = [];
+  params: [],
+  emit: (plan, amounts) => {
+    const stages: FxStagePlan[] = [];
     EQ_BANDS.forEach((band, i) => {
-      const gain = read(params, EQ_PARAMS[i]!);
-      if (gain !== 0)
+      const gain = held(amounts[band.key], EQ_ROWS[i]!);
+      if (!isNone(gain))
         stages.push({ kind: 'filter', filter: band.filter, frequency: band.frequency, gain, q: PEAK_Q });
     });
-    return stages.length === 0 ? chain : { ...chain, stages: [...chain.stages, ...stages] };
+    return stages.length === 0 ? plan : { ...plan, stages: [...plan.stages, ...stages] };
   },
 };
 
@@ -145,3 +197,26 @@ export const SOUND_FX_NODES: readonly SoundFxNodeDef[] = [
   SoundFxPitch,
   SoundFxEq,
 ];
+
+/** An amount with the value handed in for its parameter, held to its row; a 0 there does nothing. */
+function amountOf(amount: FxAmount, params: FxParams): number {
+  const given = amount.param !== undefined ? params[amount.param] : undefined;
+  if (given === undefined || !Number.isFinite(given)) return amount.value;
+  return Math.max(amount.min ?? -Infinity, Math.min(amount.max ?? Infinity, given));
+}
+
+/** The chain one voice is sent along: the plan with every parameter filled in. */
+export function fxChainOf(plan: FxPlan, params: FxParams = {}): FxChain {
+  const stages: FxStage[] = [];
+  for (const stage of plan.stages) {
+    if (stage.kind === 'gain') {
+      const db = amountOf(stage.db, params);
+      if (db !== 0) stages.push({ kind: 'gain', gain: 10 ** (db / 20) });
+      continue;
+    }
+    const gain = amountOf(stage.gain, params);
+    if (gain !== 0) stages.push({ ...stage, gain });
+  }
+  const pitch = plan.pitch.reduce((sum, amount) => sum + amountOf(amount, params), 0);
+  return { pitch, stages };
+}

src/core/store/serialize.ts

@@ -487,6 +487,8 @@ function normalizePorts(raw: unknown, fixed: readonly string[], writable: boolea
     // A machine that is gone is kept, as a struct type is: the port then offers no states.
     if (kind === 'statemachine' && typeof p.machine === 'string' && p.machine !== '')
       port.machine = p.machine;
+    if (kind === 'number' && typeof p.default === 'number' && Number.isFinite(p.default))
+      port.default = p.default;
     ports.push(port);
   }
   return ports;