wsg/lib/examples/meshes/README.md

Meshes, Materials & Import

Examples covering geometry and materials: the minimal workflow, the 3D MVP, PBR shading, file import, and the low-level (non-App) workflow.

Example	Run command	What it shows
simple	cargo run -p wsg-lib --example simple	The minimal declarative workflow: a flat two-tone quad, unlit, rendered automatically
cube	cargo run -p wsg-lib --example cube	The 3D MVP: a textured (checkerboard) cube, lit (directional + point + spot), spinning
pbr	cargo run -p wsg-lib --example pbr	PBR metallic/roughness + normal mapping
import	cargo run -p wsg-lib --example import --features import-obj	OBJ file import (non-graphical, prints stats to stdout)
manual	cargo run -p wsg-lib --example manual	The advanced workflow: Context/Renderer/PipelineCache driven by hand, without the App facade

All commands run from the repo root. The import example additionally requires the import-obj Cargo feature.

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simple — Minimal Declarative Workflow

The "15 lines, no wgpu" model: AppBuilder creates the window + GPU, and App::run drives the update → render → present loop. The scene renders automatically — the default AppHandler::render calls app.render_scene(frame.view()).

The mesh is a flat two-tone quad declared from a Geometry (per-vertex positions + colors) and drawn with the standard shader in unlit mode (renderer.set_unlit(true)): flat 2D is a special case of 3D, one pipeline for all.

cargo run -p wsg-lib --example simple

No keys — static render.

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cube — The 3D MVP

A lit unit cube that rotates, textured with a procedural 8×8 checkerboard via the diffuse path (bind group @group(2)). Follows the declarative workflow (like simple): AppBuilder + automatic scene, no wgpu import. The texture is generated procedurally (RGBA bytes → Texture::from_rgba8) to stay self-contained; the default camera at (0, 0, 3) frames the cube, and update() rotates the entity via set_entity_transform each frame.

cargo run -p wsg-lib --example cube

No keys — the cube spins on its own.

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pbr — PBR Metallic/Roughness + Normal Mapping

Demonstrates the Cook-Torrance PBR workflow: GGX distribution + Smith geometry + Schlick Fresnel + hemispheric IBL + normal mapping.

cargo run -p wsg-lib --example pbr

Key	Action
Drag (LMB)	Orbit camera
Wheel	Zoom
R	Reset camera

Scene: 6 PBR materials (mirror metal, smooth plastic, rusty metal, ceramic, bump map, matte floor). The bump-map cube shows procedural sin-wave surface detail.

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import — OBJ File Import

Non-graphical example: parses a .obj file and prints statistics (vertex count, normals, UVs, indices, bounding box) to stdout.

# With a file:
cargo run -p wsg-lib --example import --features import-obj -- /path/to/model.obj

# Without argument (demo triangle):
cargo run -p wsg-lib --example import --features import-obj

No keys — runs and exits.

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manual — Low-level Workflow (no App facade)

Demonstrates the API without the App facade: direct use of Context, Renderer, PipelineCache, Mesh, Material. Renders a colored quad (unlit).

Useful for understanding what the App facade encapsulates:

• Context (Manager layer): GPU lifecycle — Instance/Surface/Adapter/ Device/Queue, configure() for the swapchain, per-frame surface texture.
• Renderer (Executor layer): render(view, mesh, material) = one object per submission; present(frame).
• PipelineCache: register_shader(id, path) then Material::new(format, id, &mut cache).

The window and GPU are created in winit 0.30's resumed() callback (run_app + ApplicationHandler). The two-layer architecture is detailed in docs/tech/ARCHI_APP.md and FRAME_LOOP.md.

cargo run -p wsg-lib --example manual

No keys — static render (unlit quad, 4 colors).

Tip

: start with the declarative workflow. The manual workflow doesn't render more pixels — it gives more control over command encoding.