Asynchronous thread for gravity processing

2 files changed, 59 insertions, 19 deletions

diff --git a/src/air.c b/src/air.c
index 2947d93..e859e6c 100644
--- a/src/air.c
+++ b/src/air.c
@@ -4,11 +4,15 @@
 #include <defines.h>
 float kernel[9];
 
-float ogravmap[YRES/CELL][XRES/CELL];
-float gravmap[YRES/CELL][XRES/CELL];
+float gravmap[YRES/CELL][XRES/CELL];  //Maps to be used by the main thread
 float gravx[YRES/CELL][XRES/CELL];
 float gravy[YRES/CELL][XRES/CELL];
 
+float th_ogravmap[YRES/CELL][XRES/CELL]; // Maps to be processed by the gravity thread
+float th_gravmap[YRES/CELL][XRES/CELL];
+float th_gravx[YRES/CELL][XRES/CELL];
+float th_gravy[YRES/CELL][XRES/CELL];
+
 float vx[YRES/CELL][XRES/CELL], ovx[YRES/CELL][XRES/CELL];
 float vy[YRES/CELL][XRES/CELL], ovy[YRES/CELL][XRES/CELL];
 float pv[YRES/CELL][XRES/CELL], opv[YRES/CELL][XRES/CELL];
@@ -44,7 +48,7 @@ void update_grav(void)
 			break;
 		for (j=0; j<XRES/CELL; j++)
 		{
-			if(ogravmap[i][j]!=gravmap[i][j]){
+			if(th_ogravmap[i][j]!=th_gravmap[i][j]){
 				changed = 1;
 				break;
 			}
@@ -52,13 +56,13 @@ void update_grav(void)
 	}
 	if(changed)
 	{
-		memset(gravy, 0, sizeof(gravy));
-		memset(gravx, 0, sizeof(gravx));
+		memset(th_gravy, 0, sizeof(th_gravy));
+		memset(th_gravx, 0, sizeof(th_gravx));
 		for (i=0; i<YRES/CELL; i++)
 		{
 			for (j=0; j<XRES/CELL; j++)
 			{
-				if(gravmap[i][j]>0.0f) //Only calculate with populated or changed cells.
+				if(th_gravmap[i][j]>0.0f) //Only calculate with populated or changed cells.
 					for (y=0; y<YRES/CELL; y++)
 					{
 						for (x=0; x<XRES/CELL; x++)
@@ -66,15 +70,15 @@ void update_grav(void)
 							if(x == j && y == i)//Ensure it doesn't calculate with itself
 								continue;
 							float distance = sqrt(pow(j - x, 2) + pow(i - y, 2));
-							gravx[y][x] += M_GRAV*gravmap[i][j]*(j - x)/pow(distance, 3);
-							gravy[y][x] += M_GRAV*gravmap[i][j]*(i - y)/pow(distance, 3);
+							th_gravx[y][x] += M_GRAV*th_gravmap[i][j]*(j - x)/pow(distance, 3);
+							th_gravy[y][x] += M_GRAV*th_gravmap[i][j]*(i - y)/pow(distance, 3);
 						}
 					}
 			}
 		}
 	}
-	memcpy(ogravmap, gravmap, sizeof(gravmap));
-	memset(gravmap, 0, sizeof(gravmap));
+	memcpy(th_ogravmap, th_gravmap, sizeof(th_gravmap));
+	memset(th_gravmap, 0, sizeof(th_gravmap));
 }
 void update_air(void)
 {
diff --git a/src/main.c b/src/main.c
index f98e98c..c435d3b 100644
--- a/src/main.c
+++ b/src/main.c
@@ -43,6 +43,7 @@ char pygood=1;
 #include <SDL/SDL_audio.h>
 #include <bzlib.h>
 #include <time.h>
+#include <pthread.h>
 
 #ifdef WIN32
 #include <direct.h>
@@ -189,6 +190,10 @@ sign signs[MAXSIGNS];
 
 int numCores = 4;
 
+pthread_t gravthread;// = NULL;
+pthread_mutex_t gravmutex = NULL;
+int grav_ready = 0;
+
 int core_count()
 {
 	int numCPU = 1;
@@ -2559,6 +2564,24 @@ int process_command_old(pixel *vid_buf,char *console,char *console_error) {
 	return 1;
 }
 
+void update_grav_async()
+{
+	int done = 0;
+	while(1){
+		if(!done){
+			update_grav();
+			done = 1;
+			pthread_mutex_lock(&gravmutex);
+			grav_ready = done;
+			pthread_mutex_unlock(&gravmutex);
+		} else {
+			pthread_mutex_lock(&gravmutex);
+		    done = grav_ready;
+			pthread_mutex_unlock(&gravmutex);
+		}
+	}
+}
+
 #ifdef RENDERER
 int main(int argc, char *argv[])
 {
@@ -2632,15 +2655,11 @@ int main(int argc, char *argv[])
 	char heattext[256] = "";
 	char coordtext[128] = "";
 	int currentTime = 0;
-	int FPS = 0;
-	int pastFPS = 0;
-	int elapsedTime = 0;
-	int limitFPS = 60;
-	void *http_ver_check;
-	void *http_session_check = NULL;
+	int FPS = 0, pastFPS = 0, elapsedTime = 0, limitFPS = 60;
+	void *http_ver_check, *http_session_check = NULL;
 	char *ver_data=NULL, *check_data=NULL, *tmp;
 	//char console_error[255] = "";
-	int i, j, bq, fire_fc=0, do_check=0, do_s_check=0, old_version=0, http_ret=0,http_s_ret=0, major, minor, old_ver_len;
+	int result, i, j, bq, fire_fc=0, do_check=0, do_s_check=0, old_version=0, http_ret=0,http_s_ret=0, major, minor, old_ver_len;
 #ifdef INTERNAL
 	int vs = 0;
 #endif
@@ -2844,7 +2863,11 @@ int main(int argc, char *argv[])
 		http_session_check = http_async_req_start(NULL, "http://" SERVER "/Login.api?Action=CheckSession", NULL, 0, 0);
 		http_auth_headers(http_session_check, svf_user_id, NULL, svf_session_id);
 	}
+	pthread_mutexattr_t gma;
 
+	pthread_mutexattr_init(&gma);
+	pthread_mutex_init (&gravmutex, NULL);
+	pthread_create(&gravthread, NULL, update_grav_async, NULL); //Asynchronous gravity simulation //(void *) &thread_args[i]);
 	while (!sdl_poll()) //the main loop
 	{
 		frameidx++;
@@ -2881,9 +2904,22 @@ int main(int argc, char *argv[])
 			bsy = 1180;
 		if (bsy<0)
 			bsy = 0;
-		
+
+		memset(gravmap, 0, sizeof(gravmap)); //Clear the old gravmap
 		update_particles(vid_buf); //update everything
-		update_grav();
+
+		pthread_mutex_lock(&gravmutex);
+		result = grav_ready;
+		//pthread_mutex_unlock(&gravmutex);
+		if(result) //Did the gravity thread finish?
+		{
+			memcpy(th_gravmap, gravmap, sizeof(gravmap)); //Move our current gravmap to be processed other thread
+			memcpy(gravy, th_gravy, sizeof(gravy));	//Hmm, Gravy
+			memcpy(gravx, th_gravx, sizeof(gravx)); //Move the processed velocity maps to be used
+			grav_ready = 0; //Tell the other thread that we're ready for it to continue
+		}
+		pthread_mutex_unlock(&gravmutex);
+		//update_grav();
 		draw_parts(vid_buf); //draw particles
 
 		if (cmode==CM_PERS)