SimpleXTerrain

SimpleXTerrain is an open-source procedural terrain generation addon for Godot 4 .NET (C#). It uses a visual node graph editor to define terrain generation rules and streams chunks dynamically around a camera target in real time, uploading generated data directly into Terrain3D regions.

Features

Height Generators

• Perlin Noise (single-octave gradient noise with quintic interpolation)
• Fractal Noise (multi-octave summation with turbulence blending)
• Voronoi Cellular Noise (five blend types: Flat, Closest, SecondClosest, Cellular, Organic)
• Radial Spot (circular brush stamps with hardness-controlled falloff)
• Primitive Form (gradient, pyramid, and cone generators with tiling modes)
• Texture Input and Spline Input generators

Terrain Modifiers

• Levels and Contrast (symmetrical gamma remapping)
• LUT Curve (uniform lookup table deformation)
• Blend Combiner (multi-input mask-weighted blending)
• Slope Selector (discrete neighbor delta slope masks)
• Hydraulic Erosion (Moore flow accumulation cellular automaton with O(N) radix sort drainage)
• Moore Soil Erosion (Von Neumann soil lifting and mass-conserving sediment pouring)
• Smooth Terrace (Hermite-quantized step transitions)
• Hermite Ledge (contour cliff generation with top/bottom shoulder blending)
• Shoreline Beach (multi-sweep shore relaxation and underwater sand distribution)
• Parallax Displacement (directional pixel-shift with per-axis intensity masks)
• Aspect Shading (topographic shade and highlight dot-products)
• Binomial Blur (separable multi-pass kernel smoothing)
• Discrete Laplacian Cavity (finite difference curvature detection)
• Island Mask, Ocean Level, River Generator, Lake Excavator

Biome System

• Whittaker Biome Diagram lookup (temperature and precipitation axes to biome type)
• Unified Biome Blending (partition-of-unity weight normalization across multiple biome presets)
• Biome Reference nodes for modular graph composition

Texture Splatting

• Height-based and slope-based texture weight generation
• Unified Splatmap output directly into Terrain3D control maps
• Multi-layer mask normalization ensuring weights sum to 1.0 at every texel

Object and Foliage Scatter

• Stochastic rejection sampling with mask-weighted density control
• Mitchell's Best-Candidate blue noise point distributions
• Object and foliage placement nodes (implemented but not fully stress-tested)

GPU Acceleration

• Vulkan compute shaders dispatched through Godot's RenderingDevice API
• GPU-accelerated nodes: Perlin Noise, Fractal Noise, Blend, Blur
• Chained multi-stage dispatch with ping-pong VRAM buffers and pipeline barriers
• CPU remains idle during GPU generation, preventing frame drops

Chunk Streaming

• Asynchronous generation on background .NET threads
• Dynamic Terrain3D region allocation and deallocation around the camera
• Chunk edge welding to prevent visual seams between generated regions
• Direct memory injection into Terrain3D (no disk I/O during streaming)

Spline and Path Systems

• Dijkstra pathfinding with topographic cost functions
• Gabriel Graph network generation
• Spline Conform and Stroke nodes for roads and rivers
• De Casteljau subdivision and Legendre-Gauss arc length integration

Included Demo

The addon ships with a complete self-contained demo:

• 10 biome presets: Alpine Peaks, Badlands Oasis, Desert, Eldritch Canyonlands, Everest Range, Glacial Valley, Mountain Valleys, Mountains, Plains, Terraced Hills
• world.tres: A combined graph blending all 10 biomes into a single Whittaker-classified procedural world
• infinite_demo.tscn: Ready-to-run demo scene with a fly camera
• Terrain3D: Bundled in the repository under addons/terrain_3d

Requirements

• Godot 4.6.3 .NET Edition
• .NET 8.0 SDK
• Terrain3D (included in the repository)

Documentation

Full technical documentation is available at: https://github.com/prajwal-mx/simplex-terrain-docs

Known Limitations

• The foliage and object scattering system is implemented but not fully stress-tested due to hardware constraints during development. Community testing and contributions are welcome.
• The GPU path currently covers Perlin noise, fractal noise, blend, and blur nodes. Remaining nodes use the CPU async path.