1 files changed, 40 insertions, 0 deletions

diff --git a/simloop/include/simloop.h b/simloop/include/simloop.h
new file mode 100644
index 0000000..6a83b23
--- /dev/null
+++ b/simloop/include/simloop.h
@@ -0,0 +1,40 @@
+#pragma once
+
+#include <stdint.h>
+
+typedef uint64_t simloop_time_t; ///< Time delta in nanoseconds.
+
+typedef struct SimloopArgs {
+  int update_fps;     ///< Update frame rate. Must be >0.
+  int max_render_fps; ///< Render frame rate cap. 0 to disable.
+} SimloopArgs;
+
+typedef struct SimloopOut {
+  uint64_t       frame;          ///< Frame counter.
+  simloop_time_t update_elapsed; ///< Amount of time elapsed in the simulation.
+  simloop_time_t update_dt;      ///< Delta time for simulation updates.
+  simloop_time_t throttle;      ///< Render throttle if max render fps is given.
+  double         percent_frame; ///< Percent progress between this frame and
+                                ///< the next. Used for smooth animation.
+  bool should_update;           ///< Whether the simulation should update.
+} SimloopOut;
+
+typedef struct SimloopTimeline {
+  simloop_time_t ddt;  ///< Desired delta time.
+  simloop_time_t time; ///< Time point of the last simulation step.
+} SimloopTimeline;
+
+typedef struct Simloop {
+  simloop_time_t  clock;      ///< Tracks simulation time.
+  uint64_t        frame;      ///< Frame counter, number of updates done.
+  SimloopTimeline update;     ///< Update timeline.
+  simloop_time_t  render_ddt; ///< Desired render delta time.
+} Simloop;
+
+/// Create a simulation loop.
+Simloop simloop_make(const SimloopArgs*);
+
+/// Step the simulation loop.
+///
+/// The simulation always triggers a render of the initial state of simulation.
+void simloop_update(Simloop*, simloop_time_t dt, SimloopOut*);