Add RHI global context allocator

2026-07-11 11:34:30 +01:00
parent 943f00345c
commit bffe9b8174
8 changed files with 376 additions and 295 deletions
@@ -0,0 +1,115 @@
+# Plan: RHI Global Context
+
+## Goal
+
+Replace per-call `WpAllocator *allocator` parameters with a global `PrRhiContext`
+managed by the RHI. The RHI owns the lifetime of all objects it creates.
+
+## Changes
+
+### 1. `src/prism/rhi/pr_rhi_types.h` — Add context struct
+
+Add after the existing typedefs:
+
+```c
+typedef struct PrRhiContext {
+	WpAllocator main;     // objects returned to the user
+	WpAllocator scratch;  // internal temporaries within functions
+} PrRhiContext;
+```
+
+### 2. `src/prism/rhi/pr_rhi.h` — Public API changes
+
+- Add `wp_extern PrRhiContext _G_RHI_CONTEXT;` declaration (near top, after includes)
+- Add `wp_extern b8 prRhiInit(void);` and `wp_extern void prRhiDestroy(void);`
+- Remove `WpAllocator *allocator` (and `const WpAllocator *allocator`) from **all** function signatures
+
+### 3. `src/prism/rhi/pr_rhi.c` — New file (shared across backends)
+
+```c
+#include "pr_rhi.h"
+
+PrRhiContext _G_RHI_CONTEXT;
+
+b8 prRhiInit(void) {
+	_G_RHI_CONTEXT.main    = wpMemArenaAllocatorInit(MiB(64));
+	_G_RHI_CONTEXT.scratch = wpMemArenaAllocatorInit(MiB(32));
+	return true;
+}
+
+void prRhiDestroy(void) {
+	wpMemAllocatorFree(&_G_RHI_CONTEXT.scratch, ...);
+	wpMemAllocatorFree(&_G_RHI_CONTEXT.main, ...);
+}
+```
+
+### 4. `src/prism/rhi/vulkan/pr_rhi_vk.h` — Remove allocator from Vk declarations
+
+Remove `WpAllocator *allocator` from all function declarations.
+
+### 5. `src/prism/rhi/vulkan/pr_rhi_vk.c` — Implementation changes
+
+For every function that previously took `WpAllocator *allocator`:
+
+- Remove the parameter from the signature
+- Replace `allocator` with `_G_RHI_CONTEXT.main` for:
+  - `wpMemAllocatorAlloc(allocator, sizeof(...))` for user-facing objects (returned to caller)
+  - `wpArrayAllocCapacity(...)` for arrays that are stored in user-facing structs
+- Replace `allocator` with `_G_RHI_CONTEXT.scratch` for:
+  - `wpArrayAllocCapacity(...)` for internal temporary arrays
+  - `wpArrayDealloc(...)` for internal temporaries
+- Replace `wpMemAllocatorFree(allocator, ...)` with `wpMemAllocatorFree(&_G_RHI_CONTEXT.main, ...)` for destroy functions
+- Update internal calls (e.g. `prRhiCreateBufferVk` called from `prRhiCreateTextureFromKtxVk`)
+
+**Specific internal/helper changes:**
+- `_createSwapchainTexture` — remove `allocator` param, use `_G_RHI_CONTEXT.main`
+- `prRhiCreateTextureFromKtxVk` — staging buffer uses `_G_RHI_CONTEXT.main` (it's a user-facing object destroyed by the user)
+- `prRhiAllocateCommandBuffersVk` — VkCommandBuffer temp array uses scratch, PrRhiCommandBuffer array + structs use main
+- `prRhiCreatePipelineLayoutVk` — VkDescriptorSetLayout/VkPushConstantRange overflow arrays use scratch
+- `prRhiCreateDeviceVk` — VkQueueFamilyProperties2 array uses scratch
+
+### 6. `src/prism/rhi/vulkan/pr_rhi_vk_aliases.h` — No changes needed
+
+Aliases only map function names, not parameters.
+
+## Allocator usage per function
+
+| Function | Returned object | Allocator |
+|----------|----------------|-----------|
+| `prRhiCreateInstance` | PrRhiInstance | main |
+| `prRhiDestroyInstance` | — | free from main |
+| `prRhiGetPhysicalDevices` | PrRhiPhysicalDeviceArray + PrRhiPhysicalDevice structs | main |
+| `prRhiCreateSurfaceFromWindow` | PrRhiSurface | main |
+| `prRhiDestroySurface` | — | free from main |
+| `prRhiCreateDevice` | PrRhiDevice | main (internal VkQueueFamilyProperties2 array → scratch) |
+| `prRhiDestroyDevice` | — | free from main |
+| `prRhiCreateSwapchain` | PrRhiSwapchain + images + depth | main (internal VkImage array → scratch) |
+| `prRhiDestroySwapchain` | — | free from main |
+| `prRhiRecreateSwapchain` | updates existing struct | main for new images/depth, scratch for temp arrays |
+| `prRhiCreateBuffer` | PrRhiBuffer | main |
+| `prRhiDestroyBuffer` | — | free from main |
+| `prRhiCreateTexture` | PrRhiTexture | main |
+| `prRhiCreateTextureFromKtx` | PrRhiTexture (staging buffer too) | main |
+| `prRhiDestroyTexture` | — | free from main |
+| `prRhiCreateSampler` | PrRhiSampler | main |
+| `prRhiDestroySampler` | — | free from main |
+| `prRhiCreateShader` | PrRhiShader | main |
+| `prRhiDestroyShader` | — | free from main |
+| `prRhiCreatePipelineLayout` | PrRhiPipelineLayout | main (internal overflow arrays → scratch) |
+| `prRhiDestroyPipelineLayout` | — | free from main |
+| `prRhiCreateGraphicsPipeline` | PrRhiPipeline | main |
+| `prRhiCreateComputePipeline` | PrRhiPipeline | main |
+| `prRhiDestroyPipeline` | — | free from main |
+| `prRhiCreateDescriptorSetLayout` | PrRhiDescriptorSetLayout | main |
+| `prRhiDestroyDescriptorSetLayout` | — | free from main |
+| `prRhiCreateDescriptorPool` | PrRhiDescriptorPool | main |
+| `prRhiDestroyDescriptorPool` | — | free from main |
+| `prRhiAllocateDescriptorSet` | PrRhiDescriptorSet | main |
+| `prRhiFreeDescriptorSet` | — | free from main |
+| `prRhiCreateFence` | PrRhiFence | main |
+| `prRhiDestroyFence` | — | free from main |
+| `prRhiCreateSemaphore` | PrRhiSemaphore | main |
+| `prRhiDestroySemaphore` | — | free from main |
+| `prRhiCreateCommandPool` | PrRhiCommandPool | main |
+| `prRhiDestroyCommandPool` | — | free from main |
+| `prRhiAllocateCommandBuffers` | PrRhiCommandBufferArray + structs | main (internal VkCommandBuffer array → scratch) |