C++ 3D engine targeting Apple Metal on macOS/iOS.

VisuTwin Canvas is a C++23 port of the PlayCanvas engine, re-architected for native Metal rendering. It provides a forward PBR renderer, ECS framework, asset pipeline, and composable shader system.

Namespace

All engine types live under visutwin::canvas.

Architecture

Engine::render()
  -> ForwardRenderer::buildFrameGraph()
    -> FrameGraph::compile()
      -> FrameGraph::render()

Render Passes

Pass	Purpose
RenderPassForward	Main PBR geometry (multi-light, multi-layer)
RenderPassShadowDirectional	Directional shadow cascades
RenderPassShadowLocalClustered	Local light shadows (clustered)
RenderPassShadowLocalNonClustered	Local light shadows (non-clustered)
RenderPassUpdateClustered	CPU-side clustered lighting grid
RenderPassPostprocessing	Orchestrates DOF, SSAO, TAA, compose
RenderPassCookieRenderer	Light cookie projection

Compute / Post-Processing Passes

TAA, SSAO, depth-aware blur, circle of confusion, DOF blur, compose (tonemapping + bloom + vignette), GPU instance culling, LIC (flow visualization), marching cubes, particle compute.

Modules

See the Modules page for a categorized overview:

Core — Math, shapes, events, utilities
Platform — Graphics abstraction and Metal backend
Scene — Scene graph, renderer, materials, lighting, shaders
Framework — ECS, assets, parsers, gizmos

Material System

Material — Base class: glTF PBR metallic-roughness
StandardMaterial — Full PBR (clearcoat, anisotropy, sheen, iridescence, transmission)
ShaderMaterial — Custom Metal shaders with user entry points

ECS

GraphNode -> Entity -> Components via ComponentSystem<T> registry.

11 component types: Camera, Render, Light, Script, Animation, Screen, Element, Button, Collision, RigidBody, GSplat.

Building

cmake --preset default

cmake --build build

Requires C++23, CMake 3.28+, vcpkg manifest mode. See the repository README for details.

Building the Documentation

./tools/build-docs.sh

open docs/api/html/index.html