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Diffstat (limited to 'src/rendering/rhi')
| -rw-r--r-- | src/rendering/rhi/rhi.h | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/src/rendering/rhi/rhi.h b/src/rendering/rhi/rhi.h new file mode 100644 index 0000000..f64252c --- /dev/null +++ b/src/rendering/rhi/rhi.h @@ -0,0 +1,131 @@ +#pragma once + +// Donut RHI (Render Hardware Interface): a small, portable GPU abstraction that +// OpenGL, Vulkan (and later Metal / D3D12) implement behind ONE interface, so the +// app's rendering — the black hole, the scene — is written ONCE on top and runs +// on any backend. The shape is modelled on the explicit APIs (baked pipelines, +// recorded command lists, explicit render targets); OpenGL emulates that, which +// is easy, whereas the reverse (making Vulkan speak GL's immediate mode) is not. + +#include "core/memory.h" +#include <glm/glm.hpp> +#include <cstdint> +#include <string> +#include <vector> +#include <functional> + +namespace Donut::rhi +{ + enum class Format + { + RGBA8, // 8-bit unorm colour (swapchain / LDR targets) + RGBA16F, // half-float colour (HDR / cubemap) + D32, // 32-bit depth + }; + + enum class BufferType { Vertex, Index, Uniform }; + enum class Topology { Triangles, Lines }; + enum class CullMode { None, Back, Front }; + enum class BlendMode { Opaque, AlphaBlend }; + enum class CompareOp { Always, Less, LessEqual }; + enum class Filter { Nearest, Linear }; + + // One vertex attribute; offsets/stride are in bytes. `components` is 1..4 floats. + struct VertexAttribute { uint32_t location; uint32_t components; uint32_t offset; }; + struct VertexLayout { uint32_t stride = 0; std::vector<VertexAttribute> attributes; }; + + // A shader resource slot the pipeline exposes. `binding` is the set-0 binding + // index shared by the GLSL/SPIR-V (the app binds resources to these before a draw). + enum class ResourceKind { UniformBuffer, Texture }; + struct ResourceSlot { ResourceKind kind; uint32_t binding; }; + + // --- opaque GPU resources (backends subclass) -------------------------- + class Buffer { public: virtual ~Buffer() = default; virtual auto update(const void* data, size_t size) -> void = 0; }; + class Texture { public: virtual ~Texture() = default; }; + class Pipeline{ public: virtual ~Pipeline() = default; }; + + // An off-screen target (colour, optional depth). The swapchain is the implicit + // default target, addressed by passing nullptr to begin_render_pass. + class RenderTarget + { + public: + virtual ~RenderTarget() = default; + virtual auto width() const -> int = 0; + virtual auto height() const -> int = 0; + virtual auto color_texture() -> Texture* = 0; // to sample this target's colour + }; + + struct PipelineDesc + { + std::string shader; // base name; backend loads .spv or .glsl + VertexLayout vertex_layout; + std::vector<ResourceSlot> resources; // UBO/texture slots the shader reads + Topology topology = Topology::Triangles; + CullMode cull = CullMode::None; + BlendMode blend = BlendMode::Opaque; + bool depth_test = false; + bool depth_write = false; + CompareOp depth_op = CompareOp::Less; + Format color_format = Format::RGBA8; // format of the target it renders into + bool has_depth = false; // target has a depth attachment + }; + + // Records draws for one frame. Obtained from Device::begin_frame (targets the + // swapchain) or created transiently for off-screen passes via the Device. + class CommandList + { + public: + virtual ~CommandList() = default; + + // target == nullptr renders to the swapchain; otherwise to the RenderTarget. + virtual auto begin_render_pass(RenderTarget* target, const glm::vec4& clear) -> void = 0; + virtual auto end_render_pass() -> void = 0; + + virtual auto bind_pipeline(Pipeline* pipeline) -> void = 0; + virtual auto set_viewport(int x, int y, int w, int h, bool flip_y = false) -> void = 0; + + virtual auto bind_uniform(uint32_t binding, Buffer* ubo) -> void = 0; + virtual auto bind_texture(uint32_t binding, Texture* texture) -> void = 0; + + virtual auto bind_vertex_buffer(Buffer* vb) -> void = 0; + virtual auto bind_index_buffer(Buffer* ib) -> void = 0; // 32-bit indices + + virtual auto draw(uint32_t vertex_count) -> void = 0; + virtual auto draw_indexed(uint32_t index_count) -> void = 0; + }; + + // The backend root: owns the device/swapchain and creates every resource. + class Device + { + public: + virtual ~Device() = default; + + // glfwWindow: opaque GLFW handle (GL context for OpenGL, NO_API otherwise). + virtual auto init(void* glfwWindow, int width, int height) -> bool = 0; + virtual auto shutdown() -> void = 0; + virtual auto resize(int width, int height) -> void = 0; + virtual auto wait_idle() -> void = 0; + + virtual auto create_buffer(BufferType type, size_t size, const void* data = nullptr) -> Ref<Buffer> = 0; + virtual auto create_texture(int width, int height, Format format, Filter filter, const void* data = nullptr) -> Ref<Texture> = 0; + virtual auto create_cubemap_from_hdri(const std::string& equirect_path) -> Ref<Texture> = 0; + virtual auto create_render_target(int width, int height, Format color, bool with_depth, + Filter sample_filter = Filter::Linear, int mip_levels = 1) -> Ref<RenderTarget> = 0; + virtual auto create_pipeline(const PipelineDesc& desc) -> Ref<Pipeline> = 0; + + // Frame loop: begin_frame returns the swapchain command list (or nullptr if + // the frame is skipped, e.g. minimised); record into it, then end_frame + // submits + presents. record_offscreen runs a self-contained pass whose + // command list targets a RenderTarget (used before the swapchain frame). + virtual auto begin_frame(const glm::vec4& clear) -> CommandList* = 0; + virtual auto end_frame() -> void = 0; + virtual auto record_offscreen(const std::function<void(CommandList&)>& record) -> void = 0; + + // ImGui lives above the RHI but its platform/render backend is per-device. + virtual auto init_imgui() -> void = 0; + virtual auto imgui_new_frame() -> void = 0; + virtual auto imgui_render(CommandList& swapchain_cmds) -> void = 0; + + virtual auto device_name() const -> const std::string& = 0; + }; +} |