Procedural World

An OpenGL 4.1 procedural planet renderer built with GLFW, GLAD, GLM, and xmake.

Features

• Cube-sphere planet rendering with tessellation shaders
• Per-face quadtree LOD on the CPU
• Erosion-driven fractal tributary river rendering from channel/flow masks
• Shaded, wireframe, height-map, and normal visualization modes
• Fly camera controls for inspecting the planet at multiple scales

Project Structure

include/
  FlyCamera.h        Camera movement and view-matrix helper
  PlanetRenderer.h   Planet rendering API and LOD-facing data structures
  ShaderProgram.h    Shader compilation helper with lightweight #include support

src/
  main.cpp           GLFW application entry point and input wiring
  PlanetRenderer.cpp Planet mesh rendering, cube-sphere mapping, and quadtree LOD

shaders/
  terrain.vert       Node-local UV remapping for the current quadtree patch
  terrain.tesc       Distance-based tessellation control
  terrain.tese       Cube-sphere displacement and normal generation
  terrain.frag       Fragment shader entry point
  terrain_types.glsl Shared terrain fragment data structures
  terrain_surface.glsl Surface color and slope classification
  terrain_lighting.glsl Lighting, fog, and tone mapping helpers
  terrain_debug.glsl Debug visualization helpers
  wire_fine.frag     Fine wireframe overlay color
  wire_coarse.frag   Coarse quadtree grid overlay

Build

1. Install xmake.
2. Build the project:

xmake build

3. Run the executable:

xmake run -y

Controls

• W/A/S/D: move camera
• Q/E: move down/up
• Right Mouse + Drag: rotate camera
• Left Mouse + Drag: rotate planet manually
• Mouse Wheel: zoom
• 1: shaded mode
• 2: toggle wireframe overlay
• 3: height-map mode
• 4: normal mode
• Esc: quit

Notes

• Shaders are copied into the build output automatically by xmake.lua.
• The current LOD system is a first-pass quadtree implementation. It improves patch density around the camera but does not yet stitch mixed-depth patch borders.

Progress

Team size: 3 | Target: 15p | Current estimate: 11.5p conservative / 12.5p defensible

Current Score Estimate

The old 5.5p estimate is outdated. The current code now includes CPU procedural planet data, climate/biome fields, hydraulic and thermal erosion, fractal tributary river extraction from channel/flow masks, FFT ocean waves, planar reflection/refraction, depth-based water color, Fresnel mixing, and atmospheric scattering.

Module	Current implementation	Conservative	Defensible
Noise terrain geometry	CPU procedural height generation with gradient noise/fBM, continents, mountains, basins, ocean floor, uploaded as GPU texture arrays	1p	1p
Variable-resolution tessellation / LOD	CPU cube-face quadtree LOD, frustum/horizon culling, shore-aware refinement, GPU tessellation control shader	2p	2p
Sphere / cube-sphere tessellation	Six cube faces mapped to a sphere in tessellation evaluation shader; height displaces along sphere normal	1p	1p
Height-, slope-, biome-based shading	Height/slope/biome/erosion-aware procedural material blending with debug masks	1p	1p
Basic water + FFT waves	Spherical ocean pass, FFT height/normal/displacement textures, choppy displacement, detail normals	2p	2p
Texture splatting / material blending	Procedural biome-weight material blending exists, but not full real-texture splatting	0.5p	0.5p
Hydraulic + thermal erosion + rivers	CPU grid hydraulic erosion, flow, sediment capacity, erode/deposit, thermal talus smoothing, erosion masks, fractal tributary extraction, river tint/highlight/refraction-style pass	1p	1p
Water reflection & refraction	Planar reflection/refraction FBOs, depth-based color blend, Fresnel mixing, performance controls	1p	2p
Procedural sky / atmosphere	Atmosphere shell with Rayleigh/Mie-style scattering approximation and tunable density/exposure/colors	2p	2p
Procedural vegetation	Not implemented	0p	0p

Total: 11.5p conservative, 12.5p defensible.

Use the conservative total if the grader is strict about planar reflection/refraction or real texture splatting. Use the defensible total if planar reflection/refraction with depth blend and Fresnel is counted as the full water extension.

Remaining likely points: real sampled terrain texture splatting (+0.5p), more advanced/GPU erosion (+1p), procedural vegetation (+1p to +2p), and a more complete sky system with day/night or god rays (+1p to +3p).

Completed

Module	Work Done	Points
Noise terrain geometry (1p)	GPU-side height generation in TES; 6-octave fBm with lacunarity 2 / gain 0.45; domain-warped input coordinates via two fBm pre-passes; ridge noise blended for sharp peaks; surface normals computed via central finite differences	1p
Variable-resolution tessellation (2p)	TCS computes per-edge tessellation level from camera distance to edge midpoint (linear map tessMin→tessMax); TES uses fractional_even_spacing for crack-free transitions between adjacent patches	2p
Sphere tessellation (1p)	Tessellated sphere geometry as initial rendering target	1p
Height- & slope-based shading (1p)	Fragment shader assigns 7 biome colors by normalized height + surface slope (deep ocean, shallow water, sand, grass, forest, bare rock, snow); Blinn-Phong lighting with hemisphere ambient and specular highlight	0.5p
Basic water surface (1–2p)	Flat water plane rendered at sea level	1p

Subtotal: 5.5p

Planned

Texture splatting — up to 1p remaining

What to build	Expected score
+ Sample real textures per biome, blend by splat map	1p

Hydraulic erosion — 1–2p

What to build	Expected score
Basic hydraulic erosion: particle simulation on CPU or simple GPU pass, visibly smoother valleys and ridges	1p
+ Full GPU compute shader, iterative sediment carry/deposit, realistic gullies and alluvial fans	2p

Water reflection & refraction — 1p remaining

What to build	Expected score
+ Planar reflection + refraction with depth-based color blend + Fresnel	2p

Procedural sky & sun — 2–5p total

What to build	Expected score
Basic sky gradient + hardcoded sun disc	~1p
+ Preetham or Nishita atmospheric scattering, physically correct sky color	2p
+ Sun direction drives scene directional light color and intensity	3–4p
+ Full day/night cycle, sky-ambient coupling, god rays or horizon glow	5p

Procedural vegetation — 1p+

What to build	Expected score
Instanced billboard grass, placement filtered by slope and height	1p
+ 3D tree meshes (L-system or SDF), wind animation, density variation	2–3p+