1 files changed, 44 insertions, 0 deletions

diff --git a/simloop/include/simloop.h b/simloop/include/simloop.h
new file mode 100644
index 0000000..f267d40
--- /dev/null
+++ b/simloop/include/simloop.h
@@ -0,0 +1,44 @@
+/* Simulation loop module.
+ *
+ * This implements a simulation loop but in a way that the client retains
+ * control flow. The client steps the loop and then checks whether the
+ * simulation must be updated and/or the result rendered.
+ */
+#pragma once
+
+#include <timer.h>
+
+#include <stdint.h>
+
+typedef struct SimloopArgs {
+  int    update_fps;     ///< Update frame rate. Must be >0.
+  int    max_render_fps; ///< Render frame rate cap. 0 to disable.
+  Timer* timer;          ///< Timer that drives the simulation.
+} SimloopArgs;
+
+typedef struct SimloopOut {
+  uint64_t   frame;          ///< Frame counter.
+  time_delta render_elapsed; ///< Amount of time elapsed in the rendering.
+  time_delta update_elapsed; ///< Amount of time elapsed in the simulation.
+  time_delta update_dt;      ///< Delta time for simulation updates.
+  int  updates_pending; ///< Number of frames the simulation should produce.
+  bool should_render;   ///< Whether the simulation should be rendered.
+} SimloopOut;
+
+typedef struct SimloopTimeline {
+  time_delta ddt;       ///< Desired delta time.
+  time_point last_step; ///< Time of the last simulation step.
+} SimloopTimeline;
+
+typedef struct Simloop {
+  SimloopTimeline update; ///< Update timeline.
+  SimloopTimeline render; ///< Render timeline.
+  uint64_t        frame;  ///< Frame counter.
+  Timer*          timer;
+} Simloop;
+
+/// Create a simulation loop.
+Simloop simloop_make(const SimloopArgs*);
+
+/// Step the simulation loop.
+void simloop_update(Simloop*, SimloopOut*);