circuit-simulation

Circuit Simulator

A Godot 4.5 GDExtension project for visualizing and simulating electronic circuits. Parses xschem .sch schematics and .sym symbol files, renders them in 2D/3D, and optionally runs SPICE simulations via ngspice.

Setup

1. Clone with app submodules

git clone https://github.com/ismilesen/circuit-simulator.git
cd circuit-simulator
git submodule update --init godot-cpp src/xschem2spice

Do not use --recursive for the normal app build. The xschem2spice repository contains large test-fixture submodules, and one nested test dependency uses an SSH URL. Those tests are not needed to compile this project.

If you already cloned without submodules:

git submodule update --init godot-cpp src/xschem2spice

2. Build the GDExtension

scons

This compiles the C++ source in src/, including the src/xschem2spice submodule library sources, and places the resulting shared library in project/bin/.

For web exports, install and activate Emscripten before building:

scons platform=web target=template_debug threads=no
scons platform=web target=template_release threads=no

If SCons reports Required toolchain not found for platform web, Emscripten is not active in the shell that is running the build.

3. ngspice (optional, for simulation)

The simulator dynamically loads ngspice at runtime. To enable simulation:

1. Download ngspice from https://ngspice.sourceforge.io/
2. Place ngspice.dll (Windows) or libngspice.so (Linux) and sharedspice.h in a new folder named ngspice.
3. If building with ngspice headers, uncomment and set the CPPPATH line in SConstruct.

4. Open in Godot

Open the project/ folder as a Godot project (Godot 4.5+).

Adding circuit files

• Place .sch schematic files in project/schematics/.
• Place supporting .sym symbol files in project/symbols/sym/, or upload them alongside the schematic.
• You can also drag-and-drop files into the running application via the upload panel. A .sch upload is converted to a generated .spice netlist with xschem2spice; uploading a separate netlist is optional.

Project structure

circuit-simulator/
├── godot-cpp/          # Git submodule (Godot C++ bindings)
├── src/                # C++ GDExtension source (CircuitSimulator, SchParser)
├── project/            # Godot project
│   ├── bin/            # Built shared libraries + .gdextension
│   ├── camera/         # 3D camera controller
│   ├── parser/         # GDScript .sym parser
│   ├── scripts/        # 3D circuit visualizer script
│   ├── symbols/        # Circuit symbol GDScript + sym/ for .sym files
│   ├── schematics/     # Place .sch files here
│   └── ui/             # Upload panel and sidebar UI
│   └── visualizer/
│   └── simulator/
├── SConstruct          # Build configuration
└── README.md

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