A standalone desktop tool for designing, editing, and previewing RTPC (Real-Time Parameter Control) curves for Wwise-style game audio workflows. Built with WPF, SkiaSharp, and C# on .NET 10.
Wwise's built-in curve editor works, but it's tied to the project, limited to a fixed set of named interpolation shapes per segment, and has no easy way to compare curves side by side. Hearing a curve means setting the sound up inside the project first. This tool lives outside Wwise entirely: design your curves with free-form Bézier control, hear them applied to your own audio live, then use the shape as a reference when you rebuild it in your project.
- Interactive Bézier canvas: add, move, and delete control points; drag independent left/right tangent handles for free-form shaping
- Wwise-style presets: Linear, Constant, S-Curve, Inverted S-Curve, Sine (constant-power fade in and out), Exponential and Logarithmic (base 1.41 and 3). These are hand-tuned Bézier approximations of Wwise's named shapes, not exact copies. Applicable to the whole curve or a selected segment (points inside the selected segment are replaced by the preset's single segment)
- Psychoacoustic presets: Stevens' Power (loudness), Perceptual Volume (dB taper), Reverb Wet, Distance Attenuation (inverse square) and Equal-Power Crossfade. Also Bézier approximations of the named curves, tuned by ear and by eye, so they follow the general shape of the formula rather than reproducing it exactly
- Comparison view: overlay up to 4 curves on the same canvas with colour coding, and pick a curve's colour with a built-in colour picker
- Live audio preview: load a sound effect and hear your curve drive it in real time, in three modes:
- Volume: curve output drives playback gain (dB)
- Filter Cutoff: curve output drives a live low-pass filter (Hz)
- Pitch (rate-based): curve output drives playback rate; pitch and speed move together, like a sped-up record, not independent pitch-shifting
- Native C++ evaluator: a P/Invoke-backed Bézier evaluator that drives the live test-input readout. The canvas and exports use the managed implementation
- Wwise-style XML export/import: models Wwise's real curve concepts (shape names, RTPC Input/Output mapping) for round-tripping within this app and as a reference format (see Wwise XML: what "compatible" actually means below)
- JSON export: flat sample array with mapped real-world values, for custom tooling
- PNG export: high-resolution curve render for documentation or presentations
- Native project format: save and load
.rtpcefiles (JSON under the hood, fully diffable in Git) - Undo / redo: full command stack, covers point edits, presets, comparison curves, and range changes
- RTPC mapping: set real-world input/output ranges; all exports map normalised 0–1 to your actual parameter ranges, and changing the range afterward preserves each point's real value and the curve's exact shape
- Keyboard shortcuts:
Ctrl+Z/Y,Ctrl+S,Ctrl+O,Ctrl+N,Deleteto remove selected point
| Layer | Technology |
|---|---|
| UI framework | WPF (.NET 10, C#) |
| MVVM | CommunityToolkit.Mvvm 8.4.2 ([ObservableProperty], [RelayCommand]) |
| Canvas rendering | SkiaSharp 3.119.2 |
| Native evaluator | C++ via P/Invoke |
| Audio preview engine | NAudio |
| Serialisation | System.Text.Json (inbox, .NET 10) |
| Export formats | Wwise-style XML, JSON, PNG |
RTPCCurveEditor/
├── Models/ # CurvePoint, BezierCurve, CurveDocument, CurvePreset
├── ViewModels/ # MainViewModel (MVVM, all commands and state)
├── Commands/ # UndoRedoStack, ICurveCommand, concrete command classes
├── Services/ # WwiseXmlService, JsonExportService, PngExportService,
│ ProjectFileService, AudioPreviewService,
│ FilterSampleProvider, VariSpeedSampleProvider
├── Native/ # NativeEvaluator.cs: P/Invoke bindings to the C++ evaluator
├── RTPCCurveEvaluatorNative/ # Native C++ project (the evaluator itself)
├── Presets/ # PresetLibrary: curve shape presets
├── Views/ # MainWindow, CurveCanvasControl, PresetLibraryPanel,
│ InspectorPanel, ColorPickerButton
├── Converters/ # NullToBoolConverter, InverseBooleanToVisibilityConverter,
│ ActiveCurveBorderConverter
└── Resources/ # Styles.xaml (dark theme, palette, control templates)
The Bézier engine uses piecewise cubic interpolation and solves for the curve parameter at a given x (Newton iteration with a bisection fallback), so sampling stays accurate across arbitrary control point distributions. The sine fade presets closely follow sin and cos quarter waves. The other presets are hand-tuned Bézier approximations of their named shapes, and the psychoacoustic ones are inspired by the cited models (such as Stevens' power law) rather than exact evaluations of them.
- Visual Studio 2026 with both:
- the .NET desktop development workload
- the Desktop development with C++ workload (required for the native evaluator, the build will fail without it)
- .NET 10 SDK
Plain dotnet build/dotnet restore will not work for this solution, because the .NET CLI's bundled MSBuild can't build the native C++ project. Use one of these instead:
Visual Studio: open RTPCCurveEditor.slnx and press F5, or Build → Build Solution.
Command line: from a Developer Command Prompt for VS 2026 (not a plain terminal):
git clone https://github.com/Code4Al1z/RTPC_Curve_Editor.git
cd RTPC_Curve_Editor
msbuild RTPCCurveEditor.slnx /t:Build /p:Configuration=Release /p:Platform=x64
| Action | How |
|---|---|
| Add a control point | Double-click on the canvas |
| Remove a control point | Double-click an existing point |
| Move a point | Left-click drag |
| Adjust Bézier handles | Select a point, then drag its tangent handles |
| Select a curve segment | Left-click on the curve line |
| Apply a preset to selection | Select preset in sidebar → Apply Preset |
| Zoom canvas | Mouse wheel |
| Delete selected point | Delete key |
The exported XML models Wwise's real curve concepts accurately: the curve shape names (Linear, SCurve, Exp1/Exp3, Log1/Log3, Constant) match Wwise's actual RTPC interpolation types, and the Input/Output structure reflects how Wwise thinks about a Game Parameter driving a curve. It does not open in Wwise itself. Wwise's Authoring tool has no general "import an RTPC curve from a file" feature. Curve data there is set up manually in its own curve editor UI or via WAAPI. This format is for round-tripping curves within this app (lossless, with control points and handles preserved exactly) and as an accurate reference format, not for direct Wwise file interop.
Exports a flat array of { x, y, xMapped, yMapped } samples (64 by default) plus metadata. Suitable for custom tooling or engine-side lookup tables.
1200×800 high-resolution render of the curve with grid, axis labels, and anchor points. Suitable for technical documentation and pitch decks.
- Wwise XML is not literally Wwise-file-compatible: see the section above. It's an accurate reference format and a lossless round-trip format for this app, not a drop-in file for Wwise itself.
- Pitch preview mode is rate-based, not true independent pitch-shifting, because pitch and playback speed move together, the way a sped-up record does.
- This is an unsigned executable if you download a release build. Windows may show a SmartScreen warning ("Windows protected your PC") on first launch. Click "More info" → "Run anyway" to proceed.
- Multi-curve select with
Ctrl+click - Curve symmetry and mirroring tools
- Preset save/load from user-defined library
- WAAPI-connected live preview: drive an actual running Wwise instance directly, beyond the reference XML format above
AL!Z / Aliz Pasztor, Psychoacoustic-Visual Systems Engineer alizpasztor.com