Py-NGL Demos

This repository contains a collection of examples for the PyNGL library and used in teaching across a number of NCCA courses.

It is expected you will use uv to run all the python applications. The RunDemos.py will launch all the demos in the repository.

There are two main types of demos in this repository:

• OpenGL Demos: These are demos that use Modern core profile OpenGL for rendering.
• WebGPU Demos: These are demos that use WebGPU for rendering and in a number of cases are also available as OpenGL demos.

You can see the Source for the PyNGL on GitHub and it can be installed via PyPi Full details of PyNGL and how to use it can be found at https://ncca.github.io/PyNGL/

Each demo lives in its own folder with a README.md explaining it. Click a preview or demo name below to open that folder.

To quickly run all the demos use the smoketest_all.py script which will launch all the demos for a few seconds and then exit, useful for quickly verifying that all demos are working.

Contents

• Getting Started / Templates
• OpenGL Fundamentals
• Vertex Array Objects
• Instancing & Performance
• Geometry & Meshes
• Transforms & Hierarchy
• Animation
• Textures & Materials
• Blending & Transparency
• Environment & Sky
• Curves & Interpolation
• Utah Teapots
• Selection & Picking
• Collision Detection
• Framebuffers & Post Processing
• Lighting & Shadows
• Ray Marching
• Geometry & Tessellation Shaders
• Uniforms & Buffers
• Compute Shaders
• WebGPU
• Particles & Points
• GUI

Getting Started / Templates

Preview	Demo	Description
	BlankPySide6NGL	Minimal PySide6 + NGL OpenGL window template
	BlankPySDL3	Minimal PySDL3 + NGL OpenGL window template
	BlankWebGPU	Minimal WebGPU window template
	SimplePyNGL	Simple first PyNGL examples
	SimpleWebGPU	Simple first WebGPU example

OpenGL Fundamentals

Preview	Demo	Description
	2DDrawingOpenGL	2D drawing with OpenGL
	Camera	Camera / view and projection setup
	Lights	Basic lighting
	ShadingModels	Comparison of shading models
	ScreenTri	Full-screen triangle technique
	OpenGLPrimRestart	Primitive restart index
	ResetLine	Animated line field using primitive restart in OpenGL and line-list expansion in WebGPU
	FrustumCull	View frustum culling
	FontRendering	Text / font rendering
	TexelFetch	Texture Buffer Object + texelFetch: animated height grid (OpenGL + WebGPU)
	LoadShaderFromJSon	JSON-driven shader assembly: noise-shaded teapot (OpenGL + WebGPU)
	TextureCompressor	DXT1/S3TC compressed-texture viewer + a from-scratch Python encoder
	GameKeyControl	Bitmask-indexed motion table for held multi-key combos, with record/playback (OpenGL + WebGPU)
	ImageMaze	Image pixels turned into a coloured cube maze with collision-aware actor controls (OpenGL + WebGPU)

Vertex Array Objects

Preview	Demo	Description
	VAOPrimitives	Built-in VAO primitives
	VertexArrayObject/Sphere	Generating a sphere VAO
	VertexArrayObject/Boid	Simple Boid VAO
	VertexArrayObject/BoidShaded	Shaded Boid VAO
	VertexArrayObject/ChangingVAO	Updating VAO data
	VertexArrayObject/ChangingVAOMultiBuffer	Updating a multi-buffer VAO
	VertexArrayObject/MultiBufferVAO	Multi-buffer VAO
	VertexArrayObject/SimpleIndexVAOFactory	Indexed VAO factory
	VertexArrayObject/ExtendedVAOFactory	Custom / extended VAO factory

Instancing & Performance

Preview	Demo	Description
	Instancing	GPU instancing vs a Python draw-call loop, with an on-screen frame-time HUD (OpenGL + WebGPU)

Geometry & Meshes

Preview	Demo	Description
	ObjViewer	Load and view Obj meshes
	ColourObj	Obj mesh with per-vertex colour
	Obj2Numpy	Convert Obj data to NumPy arrays
	KleinBottle	Procedural Klein bottle
	MarchingCubes	Metaballs polygonised into a mesh every frame with vectorised Marching Cubes

Transforms & Hierarchy

Preview	Demo	Description
	SceneGraph	A robot arm built from a minimal, unit-tested transform-hierarchy Node class
	MatrixStack	Hand-rolled push/pop matrix stack driving a hierarchy of trolls and an orbiting sphere ring (OpenGL + WebGPU)
	LookAtDemos	Interactive perspective camera against a 2x2 orthographic multi-view comparison of the same scene (OpenGL + WebGPU)
	ViewToWorldTransform	Shift-click to unproject a screen position into a world-space point (OpenGL + WebGPU)
	AffineTransforms	Translate/rotate/scale composition order (RTS vs TRS vs axis-angle) shown live against a Mat4 readout (OpenGL + WebGPU)

Animation

Preview	Demo	Description
	SkeletalAnimation	Linear blend skinning vs dual-quaternion skinning, and the "candy wrapper" artefact that tells them apart (OpenGL)
	MassSpring	Damped mass spring chain with RK4 integration, from a single spring up to a rope
	SkinnedMeshImport	Importing a rigged mesh with impasse (Python assimp) and skinning it on the GPU (OpenGL and WebGPU)
	MorphObj	Vertex-shader blending between three OBJ poses (OpenGL + WebGPU)
	BVHViewer	BVH motion-capture player with a scrubbable timeline, playback range and Four Views layout (OpenGL + WebGPU)

Textures & Materials

Preview	Demo	Description
	SimpleTexture	Basic texture mapping
	AnimatedTextures	Animated / scrolling textures
	ShowMipmap	Visualising mipmap levels
	ImageHeightMap	Displacement from a height map image
	NormalMapping	Tangent-space normal mapping
	PBR/SimplePBR	Simple physically based rendering
	PBR/PBRTexture	Textured physically based rendering (OpenGL and WebGPU versions)
	PBR/IBL	Image-based ambient lighting for PBR: numpy-precomputed irradiance map + BRDF split-sum LUT (OpenGL)
	PBR/HDRI	Full HDRI image-based lighting: GPU-baked irradiance, prefiltered specular chain and BRDF LUT from a real HDR panorama (OpenGL and WebGPU)
	PBR/HDRIBaker	Bakes the split-sum IBL maps from an HDRI to a .npz once, offline; a separate WebGPU demo loads them with no runtime bake
	Billboards	Camera-facing quads: fixed / cylindrical / spherical billboarding modes (OpenGL)

Blending & Transparency

Preview	Demo	Description
	Blending	Alpha blending, depth write and sorting toggles (OpenGL + WebGPU)
	OITransparency	Weighted blended order-independent transparency (OpenGL + WebGPU)

Environment & Sky

Preview	Demo	Description
	SkyBoxEnvMap	Procedural cubemap skybox with reflect/refract/Fresnel teapot (OpenGL + WebGPU)

Curves & Interpolation

Preview	Demo	Description
	CurveDemos	Curve types and evaluation
	EasingFunctions	Full Penner easing set with combo box selection and live matplotlib graph
	Interpolation	Interpolation techniques
	QuatSlerp	Quaternion spherical interpolation
	GimbalLock	Euler vs quaternion orientation, side by side, with a scripted gimbal-lock demonstration

Utah Teapots

A series built on Martin Newell's original Bezier patch data, see UtahTeapots for the plan.

Preview	Demo	Description
	UtahTeapots/NewellPatches	The common 32 Bezier patch teapot tessellated with NumPy (OpenGL) and a compute shader (WebGPU), with control net, normals and patch views
	UtahTeapots/BlinnTeapot	The teapot rebuilt from Blinn's swept outlines: Newell 1975, Blinn 1976 and Crow 1987 versions, sweep animation and quarter circle error (OpenGL + WebGPU)
	UtahTeapots/CrowTeapot	Frank Crow's 1987 wire frame program as constant u / v curves, hidden lines with polygon offset / depth bias and a replay of the plot (OpenGL + WebGPU)
	UtahTeapots/DriskillTeapot	Hank Driskill's 1992 trimmed NURBS teapot: exact rational circle, inside surfaces, spout passage, trim textures and a NURBS compute shader (OpenGL + WebGPU)
	UtahTeapots/FishTeapot	Russ Fish's 2006 SCL rework of the teapot: modelling as a program, his cleaver and butcher block scene, stencil capped sections and Blinn shadows (OpenGL + WebGPU)
	UtahTeapots/YukselTeapot	Cem Yuksel's 2026 version: the seams made curvature continuous by degree elevation or by splitting, reflection lines and curvature colours, a solid interior with a solid knob, both bottoms (OpenGL + WebGPU)

Selection & Picking

Preview	Demo	Description
	ColourSelectionOpenGL	Unique colour-ID picking
	RayPickingSelection	Ray-cast selection and manipulation
	SelectionManipulator	Maya-style manipulator (OpenGL)
	SelectionManipulatorWebGPU	Manipulator (WebGPU)
	WebGPUComputePicking	Compute-shader picking (WebGPU)
	StencilOutline	Maya-style two-pass stencil-buffer selection outline (OpenGL)

Collision Detection

Preview	Demo	Description
	Collisions/SphereSphere	Two moving spheres bounce off two static ones (analytic sphere/sphere test) (OpenGL + WebGPU)
	Collisions/RaySphere	N spheres tested each tick against 2 animated sweeping rays (OpenGL + WebGPU)
	Collisions/RayTriangle	N triangles tested every frame against a keyboard-moved ray (Moller-Trumbore) (OpenGL + WebGPU)
	Collisions/SpherePlane	N falling spheres collide with a tiltable plane (OpenGL + WebGPU)
	Collisions/BoundingBox	N spheres bounce inside a cubic bounding box, optional sphere/sphere checking (OpenGL + WebGPU)
	OctreeAbstract	Perfect octree broad phase with instanced particle rendering (OpenGL + WebGPU)
	MuJoCoNGL	Rigid body physics with MuJoCo, spawning bodies into a model that cannot be added to (OpenGL)

Framebuffers & Post Processing

Preview	Demo	Description
	FBODemos/SimpleFBO	Simple framebuffer object
	FBODemos/Blit	Blitting between framebuffers
	FBODemos/DOF	Depth of field
	FBODemos/WebGPURenderToTexture	Render to texture (WebGPU)
	PostProcessChain	HDR bloom + tonemap post-process chain (OpenGL)

Lighting & Shadows

Preview	Demo	Description
	DefferedLighting	Deferred lighting (WebGPU)
	WebGPUShadows	PCF shadow mapping (WebGPU)
	ShadowMapping	Two-pass depth-map shadows with PCF, bias and culling toggles (OpenGL)
	AreaLighting	Movable rectangular area light with a sampled GGX/Lambert emitter (OpenGL + WebGPU)
	Spotlight	Four animated cone-attenuation spotlights sweeping a grid of teapots (OpenGL + WebGPU)

Ray Marching

Preview	Demo	Description
	RayMarchingSDF	Sphere-traced signed distance fields, smooth-blended primitives, soft shadows + AO (OpenGL & WebGPU)

Geometry & Tessellation Shaders

Preview	Demo	Description
	GeometryTessellation	Geometry-shader normal visualiser + distance-LOD tessellated noise plane (OpenGL)
	ShadedGrid	Animated Phong-shaded wave grid with geometry-shader face/vertex normal visualisation (OpenGL)

Uniforms & Buffers

Preview	Demo	Description
	UBOStorageBuffers	UBO shared across two shader programs + std140 padding trap (OpenGL); runtime-sized storage-buffer point lights (WebGPU)

Compute Shaders

Preview	Demo	Description
	SimpleComputeWebGPU	Simple compute shader (WebGPU)
	WebGPUCompute/SpatialHash2D	2D spatial hashing on the GPU
	WebGPUCompute/SpatialHash3D	3D spatial hashing on the GPU
	BoidsCompute	Reynolds flocking with compute shaders + instanced rendering

WebGPU

Preview	Demo	Description
	WebGPUMultiGeo	Multiple geometry in one WebGPU scene

Particles & Points

Preview	Demo	Description
	Particles/ParticleQuads	Billboarded particle quads
	PointCloud	Rendering a point cloud
	Voxels	Voxel rendering

GUI

Preview	Demo	Description
	GUIDemos/PySideGUIOpenGL	PySide GUI driving an OpenGL widget
	GUIDemos/NGLWidgetsOpenGL	NGL widgets with OpenGL
	GUIDemos/WebGPUGUI	GUI driving a WebGPU widget
	GUIDemos/QMLOverlayApp	QWidget OpenGL viewport with a transparent QQuickWidget overlay of floating ncca.ngl.qml panels
	GUIDemos/QMLWebGPUOverlay	WebGPU (offscreen) viewport with a transparent QQuickWidget overlay of floating ncca.ngl.qml panels
	MathNodeEditor	PySide node editor for wiring PyNGL vector, matrix, camera, quaternion and Obj mesh operations, with a live 3D mesh viewer node
	SciFiUI	Retro sci-fi CRT terminal: Unknown Pleasures style wireframe terrain fly-over, clickable buttons, scrolling log and a two-pass CRT post process

AI Usage

This project has use various AI tools (Claude and Codex and OpenCode) to assist with development.

The initial phases were for the full port of NGL9Demos to PyNGL (C++ to Python conversion) and additional testing. Most of the work is shown in the docs section of the repository, and I have also written about various things on my blog here.

There will be a full write-up of my setup and usage of AI on the Blog soon.

License

See LICENSE.txt or just use the Beerware License