agent_compositor_test/.opencode/skills/prism-rhi/SKILL.md

name, description, license, compatibility, metadata

name	description	license	compatibility	metadata
prism-rhi	RHI (Rendering Hardware Interface) patterns — compile-time dispatch, by-value desc structs, wapp array aliases, backend file layout	MIT	opencode	domain rendering

What I do

Captures the RHI conventions for Prism: how backends are dispatched, how descriptor structs and arrays are handled, and how the files are organized.

When to use me

Use this when working on any file in src/prism/rhi/, or when creating a new backend (Vulkan, D3D12, Metal).

Conventions

Backend dispatch

Backend selection is compile-time via -D PR_RHI_VULKAN / -D PR_RHI_D3D12 / -D PR_RHI_METAL. The umbrella header pr_rhi.h includes the appropriate alias file:

#if defined(PR_RHI_VULKAN)
#  include "vulkan/pr_rhi_vk_aliases.h"
#elif defined(PR_RHI_D3D12)
#  include "d3d12/pr_rhi_d3d12_aliases.h"
#elif defined(PR_RHI_METAL)
#  include "metal/pr_rhi_metal_aliases.h"
#else
#  error "Define one of: PR_RHI_VULKAN, PR_RHI_D3D12, PR_RHI_METAL"
#endif

Each _aliases.h file maps generic names to backend-specific names:

#define prRhiCreateDevice       prRhiCreateDeviceVk
#define prRhiCreateSwapchain    prRhiCreateSwapchainVk
#define prRhiCreateBuffer       prRhiCreateBufferVk
// …

Backend implementations are suffixed with the backend name: pr_rhi_vk_device.c, pr_rhi_vk_swapchain.c, etc.

Desc structs

All descriptor structs are passed by value, not const *:

// correct
PrRhiDevice *prRhiCreateDevice(PrRhiPhysicalDevice *pdev, PrRhiSurface *surface,
                                PrRhiDeviceDesc desc, WpAllocator *alloc);

// wrong
PrRhiDevice *prRhiCreateDevice(PrRhiPhysicalDevice *pdev, PrRhiSurface *surface,
                                const PrRhiDeviceDesc *desc, WpAllocator *alloc);

File layout

src/prism/rhi/
├── pr_rhi.h              ← umbrella header (API declarations + backend dispatch)
├── pr_rhi_types.h        ← shared types (enums, element types, array aliases, desc structs, opaque handles)
├── vulkan/
│   ├── pr_rhi_vk.h       ← Vulkan backend header (opaque struct defs + Vk-suffixed decls)
│   ├── pr_rhi_vk_aliases.h ← #define alias mapping
│   └── profiles/          ← generated Vulkan Profiles library
├── d3d12/
│   └── …
└── metal/
    └── …