Initial import: LibreForts (M0-M5 in progress)

Open-source Forts clone: custom C++20 engine + data-driven (Lua) 2D physics
artillery RTS.

- Building: node/strut graph on a stiff mass-spring solver (canon Forts model),
  triangulation rigidity, axial + 30-degree angle-stress breaking, cascading
  collapse, fire (DoT + spread), ground destroys debris.
- Weapons (M4): cannon (ballistic) + laser (beam/ignite) with select-and-aim-in-
  arc UX; splash / beam damage; bg-brace passthrough.
- Devices + economy (M5): reactors + win/loss + restart, mines/turbines/battery,
  metal deposits, storage caps, per-shot energy cost.
- Data-driven via Lua/sol2 with a layered mod loader; enemy-fort scenario mod.
- Renderer: SDL3 + textures + ImGui dev UI. stb_image + ImGui vendored.
- Assets: CC0 placeholders only; real game art loaded at runtime from the user's
  own install via forts: paths (bring-your-own; nothing copyrighted committed).

See README.md / CLAUDE.md and research/ + requirements/ for detail.

1 files changed, 60 insertions, 0 deletions

diff --git a/src/engine/renderer.hpp b/src/engine/renderer.hpp
new file mode 100644
index 0000000..ddc8055
--- /dev/null
+++ b/src/engine/renderer.hpp
@@ -0,0 +1,60 @@
+#pragma once
+
+#include <SDL3/SDL.h>
+#include <vector>
+#include <string>
+#include <unordered_map>
+
+class Camera;
+
+class Renderer {
+public:
+    Renderer() = default;
+
+    bool init(SDL_Window* window, int width, int height);
+    void shutdown();
+
+    void begin_frame(Camera& camera);
+    void end_frame();
+    void resize(int width, int height);
+
+    // Draw a filled axis-aligned box in world coordinates.
+    void draw_box(float cx, float cy, float half_w, float half_h,
+                  float angle, float r, float g, float b, float a);
+
+    // Load a texture (cached by path). Returns nullptr on failure.
+    SDL_Texture* load_texture(const std::string& path);
+
+    // Draw a textured quad in world coordinates, colour-modulated by (r,g,b,a).
+    void draw_sprite(float cx, float cy, float half_w, float half_h,
+                     float angle, SDL_Texture* tex,
+                     float r = 1.0f, float g = 1.0f, float b = 1.0f, float a = 1.0f);
+
+    // Draw a simple HUD bar in screen pixels (top-left origin).
+    void draw_hud_bar(float x, float y, float fill,
+                      float r, float g, float b);
+
+    // Draw a radial (pie) countdown at a world position. `frac` in [0,1] is the
+    // remaining portion drawn as a filled wedge over a dim background ring.
+    void draw_radial_timer(float cx, float cy, float radius_world, float frac,
+                           float r, float g, float b, float a);
+
+    // Draw a filled wedge (world space) between world angles a0..a1 — used for
+    // a weapon's firing arc.
+    void draw_arc(float cx, float cy, float radius_world, float a0, float a1,
+                  float r, float g, float b, float a);
+
+    int width()  const { return width_; }
+    int height() const { return height_; }
+
+    SDL_Renderer* sdl_renderer() const { return sdl_renderer_; }
+
+private:
+    SDL_Renderer* sdl_renderer_ = nullptr;
+    Camera*       current_cam_  = nullptr;
+    int width_  = 1280;
+    int height_ = 720;
+    bool imgui_ready_ = false;
+    std::vector<SDL_Vertex> fan_scratch_;  // reused by draw_radial_timer
+    std::unordered_map<std::string, SDL_Texture*> tex_cache_;
+};