Frame budgets now in nanoseconds, game runs okayish on 5 % CPU

game/src/chunk/chunkman.c

@@ -11,7 +11,6 @@ static GHashTable *chunks;
 static GHashTable *chunk_meshes;
 
 static bool bound = false;
-static int frame_chunks = 0;
 
 guint
 chunkman_ivec2_hash (gconstpointer key)
@@ -113,22 +112,25 @@ chunkman_tick (vec3 position)
   int cx, cz;
   chunkman_world_to_chunk (position[0], position[2], &cx, &cz);
 
-  unsigned int frame_time = SDL_GetTicks ();
-  frame_chunks = 0;
+  uint64_t start = SDL_GetPerformanceCounter ();
+  uint64_t freq = SDL_GetPerformanceFrequency ();
+  double elapsed_us = 0;
   
   for (int z = cz - RENDER_DISTANCE - 1; z <= cz + RENDER_DISTANCE + 1; ++z)
     {
       for (int x = cx - RENDER_DISTANCE - 1; x <= cx + RENDER_DISTANCE + 1; ++x)
         {
+	  uint64_t now = SDL_GetPerformanceCounter ();
+	  elapsed_us = (double) (now - start) * 1000000.0 / (double) freq;
+	  
+	  if (elapsed_us > CHUNK_FRAME_BUDGET_US)
+	    {
+	      return;
+	    }
+	  
 	  if (chunkman_get_Chunk_at (x, z) == NULL)
 	    {
 	      chunkman_generate_Chunk_at (x, z);
-	      ++frame_chunks;
-	    }
-
-	  if (frame_chunks > CHUNKS_PER_FRAME || SDL_GetTicks () - frame_time > CHUNK_FRAME_BUDGET)
-	    {
-	      return;
 	    }
         }
     }
@@ -137,15 +139,17 @@ chunkman_tick (vec3 position)
     {
       for (int x = cx - RENDER_DISTANCE; x <= cx + RENDER_DISTANCE; ++x)
         {
+	  uint64_t now = SDL_GetPerformanceCounter ();
+	  elapsed_us = (double) (now - start) * 1000000.0 / (double) freq;
+
+	  if (elapsed_us > CHUNK_FRAME_BUDGET_US)
+	    {
+	      return;
+	    }
+	  
 	  if (chunkman_get_ChunkMesh_at (x, z) == NULL)
 	    {
 	      chunkman_generate_ChunkMesh_at (x, z);
-	      ++frame_chunks;
-	    }
-
-	  if (frame_chunks > CHUNKS_PER_FRAME || SDL_GetTicks () - frame_time > CHUNK_FRAME_BUDGET)
-	    {
-	      return;
 	    }
 	}
     }

game/src/chunk/chunkman.h

@@ -12,8 +12,7 @@
 #define RENDER_DISTANCE 5
 #define RENDER_SQR (RENDER_DISTANCE*RENDER_DISTANCE)
 #define TERRAIN_HEIGHT 8.0
-#define CHUNK_FRAME_BUDGET 5
-#define CHUNKS_PER_FRAME 1
+#define CHUNK_FRAME_BUDGET_US 100
 
 void chunkman_init ();
 void chunkman_tick (vec3 position);

game/src/entity/entity.h

@@ -1,9 +1,11 @@
 #pragma once
 
-#include <stdbool.h>
+/* TODO: In the future, if entities are out of the tick radius, when
+   they reappear, calculate what would happen to them during the time
+   they were out of the radius. Useful for growing plants and
+   whatnot. */
 
-/* There should also be an entity mesh type of QUAD1, as billboards
-   always face the camera, thus the back side need not be rendered. */
+#include <stdbool.h>
 
 typedef struct Entity
 {
@@ -20,6 +22,9 @@ typedef struct Entity
   void *userdata;
   
   void (*on_tick) (struct Entity *self);
+  bool tick_me_i_dont_care;	/* Tick this entity regardless of the
+				   distance and other
+				   predicates. Useful for NPCs. */
   
   vec3 position;
   vec3 rotation;

game/src/entity/entman.c

@@ -16,8 +16,6 @@ int n_frame_ents;
 static GArray *entities;
 static GQueue *spawn_requests;
 
-static int frame_ents = 0;
-
 static SimpleMesh mesh_quad1, mesh_quad2, mesh_quad_x, mesh_cube;
 static unsigned int last_program = -1;
 static unsigned int last_type = -1;
@@ -90,15 +88,19 @@ spawn_queue_process_one ()
 void
 entman_tick ()
 {
-  /* Handle spawn requests. */
-  unsigned int frame_time = SDL_GetTicks ();
-  frame_ents = 0;
+  uint64_t start = SDL_GetPerformanceCounter ();
+  uint64_t freq = SDL_GetPerformanceFrequency ();
+  double elapsed_us = 0;
 
-  while (!g_queue_is_empty (spawn_requests) && SDL_GetTicks () - frame_time < ENTITY_FRAME_BUDGET
-	 && frame_ents < ENTITIES_PER_FRAME)
+  while (!g_queue_is_empty (spawn_requests))
     {
+      uint64_t now = SDL_GetPerformanceCounter();
+      elapsed_us = (double) (now - start) * 1000000.0 / (double) freq;
+
+      if (elapsed_us > ENTITY_FRAME_BUDGET_US)
+	break;
+      
       spawn_queue_process_one ();
-      ++frame_ents;
     }
   
   /* Handle on tick events. */

game/src/entity/entman.h

@@ -17,8 +17,7 @@
 
 #define ENTADD(entity) (entman_add_entity (entity))
 
-#define ENTITY_FRAME_BUDGET 2
-#define ENTITIES_PER_FRAME 16
+#define ENTITY_FRAME_BUDGET_US 100
 
 typedef struct SpawnRequest
 {

game/src/main.c

@@ -52,8 +52,8 @@ SDL_AppIterate (void *appstate)
   UNUSED (appstate);
 
   game_state_tick (SDL_GetTicks ());
-  entman_tick ();
   chunkman_tick (camera_position);
+  entman_tick ();
   uiman_tick ();
   graphics_render ();