Implement world time single-stepping

code/game/src/debug_ui.c

@@ -95,6 +95,29 @@ static debug_item items[] = {
             }
         }
     },
+    {
+        .kind = DITEM_LIST,
+        .name = "world simulation",
+        .list = {
+            .items = (debug_item[]) {
+                { .kind = DITEM_COND, .on_success = CondIsWorldRunning },
+                { .kind = DITEM_BUTTON, .name = "pause", .on_click = ActWorldToggleSim },
+                
+                { .kind = DITEM_COND, .on_success = CondIsWorldPaused, .skip = 6 },
+                { .kind = DITEM_BUTTON, .name = "resume", .on_click = ActWorldToggleSim },
+                
+                { .kind = DITEM_GAP },
+                
+                { .kind = DITEM_TEXT, .name = "step size", .proc = DrawWorldStepSize },
+                { .kind = DITEM_BUTTON, .name = "single-step", .on_click = ActWorldStep },
+                { .kind = DITEM_BUTTON, .name = "increment step size", .on_click = ActWorldIncrementSimStepSize },
+                { .kind = DITEM_BUTTON, .name = "decrement step size", .on_click = ActWorldDecrementSimStepSize },
+                
+                { .kind = DITEM_END },
+            },
+            .is_sp_only = true,
+        }
+    },
     {
         .kind = DITEM_LIST,
         .name = "debug actions",

code/game/src/debug_ui_actions.c

@@ -233,3 +233,42 @@ ActDespawnDemoNPCs(void) {
     zpl_array_free(demo_npcs);
     demo_npcs = 0;
 }
+
+// NOTE(zaklaus): world simulation controls
+#define WORLDSIM_STEPPING 0.01f
+static float sim_step_size = 0.1f;
+
+void
+ActWorldToggleSim(void) {
+    if (world_is_paused()) {
+        world_resume();
+    } else {
+        world_pause();
+    }
+}
+
+void
+ActWorldIncrementSimStepSize(void) {
+    sim_step_size += WORLDSIM_STEPPING;
+}
+
+void
+ActWorldDecrementSimStepSize(void) {
+    if (sim_step_size > WORLDSIM_STEPPING)
+        sim_step_size -= WORLDSIM_STEPPING;
+}
+
+void
+ActWorldStep(void) {
+    world_step(sim_step_size);
+}
+
+uint8_t
+CondIsWorldPaused(void) {
+    return world_is_paused();
+}
+
+uint8_t
+CondIsWorldRunning(void) {
+    return !world_is_paused();
+}

code/game/src/debug_ui_widgets.c

@@ -91,3 +91,11 @@ DrawDemoNPCCount(debug_item *it, float xpos, float ypos) {
     (void)it;
     return DrawFormattedText(xpos, ypos, TextFormat("%d", demo_npcs ? zpl_array_count(demo_npcs) : 0));
 }
+
+
+// NOTE(zaklaus): world simulation 
+static inline debug_draw_result 
+DrawWorldStepSize(debug_item *it, float xpos, float ypos) {
+    (void)it;
+    return DrawFormattedText(xpos, ypos, TextFormat("%d ms", (int16_t)(sim_step_size*1000.f)));
+}

code/game/src/world/world.c

@@ -147,6 +147,7 @@ int32_t world_init(int32_t seed, uint16_t chunk_size, uint16_t chunk_amount) {
         return 0;
     }
     
+    world.is_paused = false;
     world.seed = seed;
     world.chunk_size = chunk_size;
     world.chunk_amount = chunk_amount;
@@ -349,6 +350,26 @@ librg_world *world_tracker() {
     return world.tracker;
 }
 
+void world_pause(void) {
+    ecs_set_time_scale(world.ecs, 0.0f);
+    world.is_paused = true;
+}
+
+void world_resume(void) {
+    ecs_set_time_scale(world.ecs, 1.0f);
+    world.is_paused = false;
+}
+
+bool world_is_paused(void) {
+    return world.is_paused;
+}
+
+void world_step(float step_size) {
+    world_resume();
+    ecs_progress(world.ecs, step_size);
+    world_pause();
+}
+
 uint16_t world_chunk_size(void) {
     return world.chunk_size;
 }

code/game/src/world/world.h

@@ -30,6 +30,7 @@ typedef WORLD_PKT_READER(world_pkt_reader_proc);
 typedef WORLD_PKT_WRITER(world_pkt_writer_proc);
 
 typedef struct {
+    bool is_paused;
     uint8_t *data;
     uint32_t seed;
     uint32_t size;
@@ -63,6 +64,12 @@ ecs_world_t *world_ecs(void);
 void world_set_stage(ecs_world_t *ecs);
 librg_world *world_tracker(void);
 
+// NOTE(zaklaus): World simulation time control
+void world_pause(void);
+void world_resume(void);
+bool world_is_paused(void);
+void world_step(float step_size);
+
 uint16_t world_chunk_size(void);
 uint16_t world_chunk_amount(void);
 uint16_t world_dim(void);