feat(particles): Étape 28 A — ParticlePool infrastructure (no driver)
Creates the GPU resource layer for particles per ARCHI §3.2/§6, without
simulation: the pool owns all buffers/pipeline/bind group but draws nothing
(indirect args zeroed → no-op) until a driver is attached (Étape B).
New:
- resources/particle.rs: Particle (80 B, #[repr(C)], no padding — D19),
SIZE/ZERO consts + offset/layout unit tests
- shaders/particle_billboard.wgsl: camera-facing billboard, empty vertex
layout (quad via vertex_index), instance slot via storage binding
compact_index (D17), uv_rect atlas support (D15/D18)
- core/particles.rs: ParticlePoolConfig, BlendingMode, ParticleDriver trait
(D3), ParticlePool (4 buffers + pipeline + bind group), default disc
texture (D11), unit tests
Wired:
- Scene: SceneGpu keeps queue/sample_count; particle_pools registry +
create_particle_pool() (default disc when no texture given)
- utils::conf PARTICLE_BILLBOARD_SHADER, module re-exports, prelude
- tests/wgsl_validate.rs: particle billboard naga validation (2 entry points)
Docs: DRAFT call-site/tree synced with the final code; AGENTS.md test count
(138) + wgpu 30 API drift gotcha (contents/DeviceExt/ALPHA_BLENDING,
DepthStencilState no Default, NonZero min_binding_size, const Zeroable).
cargo test -p wsg-lib: 138 pass (121 lib + 10 wgsl + 7), 0 warnings.
Jérôme Bousquié
49aa9e48fd