[add]: unified interface

1 files changed, 73 insertions, 0 deletions

diff --git a/src/rendering/renderer_backend.h b/src/rendering/renderer_backend.h
new file mode 100644
index 0000000..6a4f1af
--- /dev/null
+++ b/src/rendering/renderer_backend.h
@@ -0,0 +1,73 @@
+#pragma once
+
+#include <glm/glm.hpp>
+#include <functional>
+#include <string>
+#include <vector>
+
+namespace Donut
+{
+    // A placeable/editable sphere in the world-builder scene view. Backend-
+    // agnostic: the app owns the list, every backend renders it the same way.
+    struct SceneObject
+    {
+        glm::vec3 position = { 0.0f, 2.0f, 0.0f };
+        float     radius   = 2.0f;
+        glm::vec3 color    = { 0.85f, 0.35f, 0.2f };
+    };
+
+    // Live-tunable black-hole / accretion-disk parameters. Radii are in
+    // Schwarzschild radii; the inner edge is clamped to the ISCO (3 r_s).
+    struct BlackHoleParams
+    {
+        float disk_inner_rs = 3.0f;      // inner edge (x r_s)
+        float disk_outer_rs = 12.0f;     // outer edge (x r_s)
+        float temperature   = 4800.0f;   // Kelvin at the flux peak (disk colour)
+        float brightness    = 0.9f;      // disk exposure
+        float turbulence    = 0.4f;      // 0 = smooth physical disk
+        int   quality_steps = 15000;     // geodesic integration steps
+        float fov_degrees   = 60.0f;     // camera field of view
+    };
+
+    // The swappable high-level renderer. Each graphics backend (OpenGL, Vulkan,
+    // and later Metal / D3D12) implements this one interface; the Application,
+    // states and UI drive it identically, so the app behaves the same no matter
+    // which backend is active. Backends own their own device/swapchain/pipelines
+    // and translate these high-level calls into their native API.
+    class RendererBackend
+    {
+    public:
+        virtual ~RendererBackend() = default;
+
+        // glfwWindow is an opaque GLFW handle (created NO_API for Vulkan/Metal,
+        // with a GL context for OpenGL). Returns false on failure.
+        virtual auto init(void* glfwWindow, int width, int height) -> bool = 0;
+
+        // Creates the ImGui context + this backend's ImGui platform/render impl.
+        virtual auto init_ui() -> bool = 0;
+        virtual auto shutdown() -> void = 0;
+        virtual auto resize(int width, int height) -> void = 0;
+
+        // Renders one frame: draws the current view (black hole or scene) from
+        // the shared state, then invokes build_ui to draw the ImGui panel on top.
+        virtual auto draw_frame(const glm::vec4& clear_color,
+                                const std::function<void()>& build_ui) -> void = 0;
+
+        // --- shared view / camera state ------------------------------------
+        virtual auto set_scene_mode(bool enabled) -> void = 0;  // black hole vs scene view
+        virtual auto is_scene_mode() const -> bool = 0;
+        virtual auto set_free_fly(bool enabled) -> void = 0;    // free-fly vs orbital camera
+        virtual auto is_free_fly() const -> bool = 0;
+        virtual auto reset_camera() -> void = 0;
+
+        // --- shared content ------------------------------------------------
+        virtual auto set_hdri(const std::string& path) -> void = 0;
+        virtual auto current_hdri() const -> const std::string& = 0;
+        virtual auto scene_objects() -> std::vector<SceneObject>& = 0;
+        virtual auto set_selected_object(int index) -> void = 0;
+        virtual auto black_hole_params() -> BlackHoleParams& = 0;
+
+        // --- introspection for the UI --------------------------------------
+        virtual auto device_name() const -> const std::string& = 0;
+    };
+}