thread experiment

src/draw.c

@@ -1,4 +1,5 @@
 #include "draw.h"
+#include <SDL2/SDL_mutex.h>
 
 Vect viewport_pos;
 int width, height;
@@ -58,13 +59,9 @@ void draw_player(SDL_Renderer * ren, int x, int y, bool red) {
     player_rect.w = 20;
     player_rect.h = 20;
 
-    if (red) {
-        SDL_SetRenderDrawColor(ren, 255, 0, 0, 255);
-    } else {
-        struct colour c = get_scene_at(viewport_pos, level).colours.bg;
+    struct colour c = get_scene_at(viewport_pos, level).colours.bg;
 
-        SDL_SetRenderDrawColor(ren, c.r, c.g, c.b, 255);
-    }
+    SDL_SetRenderDrawColor(ren, c.r, c.g, c.b, 255);
 
     SDL_RenderDrawRect(ren, &player_rect);
     SDL_RenderFillRect(ren, &player_rect);
@@ -73,8 +70,8 @@ void draw_player(SDL_Renderer * ren, int x, int y, bool red) {
         if (!player.physics->strings[i].attached) {
             continue;
         }
-        Vect B;
-        B = in_view(player.physics->position);
+        Vect B = {x, y};
+        B = in_view(B);
         Vect E;
         E = in_view(player.physics->strings[i].end_point);
         SDL_RenderDrawLine(ren, B.x, B.y, E.x, E.y);
@@ -393,9 +390,17 @@ void redraw_buffer(SDL_Renderer * ren) {
     /*}*/
 
     int col = 0;
+    Body lplayer;
+
+    if (SDL_LockMutex(player.physics->lock) == 0){
+        lplayer = *player.physics;
+        SDL_UnlockMutex(player.physics->lock);
+    } else {
+        return;
+    }
 
 	//SDL_GetMouseState(&newmousex, &newmousey);
-    update_viewport(player.physics->position.x, player.physics->position.y);
+    update_viewport(lplayer.position.x, lplayer.position.y);
 
     struct environment scene = get_scene_at(viewport_pos, level);
     draw_environment(ren, &scene);
@@ -405,11 +410,6 @@ void redraw_buffer(SDL_Renderer * ren) {
         thing = world.get(i);
 
         switch (thing.kind) {
-            case PLAYER:
-                draw_player(ren, (*thing.player).physics->position.x, (*thing.player).physics->position.y, thing.player->colliding);
-                draw_collision_poly(ren, thing.player->physics);
-                draw_forces(ren, thing.player->physics);
-                continue;
             case STATIC_WALL_W:
                 draw_wall(ren, thing.wall);
                 draw_collision_poly(ren, thing.wall->physics);
@@ -438,6 +438,12 @@ void redraw_buffer(SDL_Renderer * ren) {
         }
     }
 
+    draw_player(ren, lplayer.position.x, lplayer.position.y, 
+            lplayer.colliding);
+    draw_collision_poly(ren, &lplayer);
+    draw_forces(ren, &lplayer);
+
+
 	/*if (newmousex != mousex || newmousey != mousey) {*/ /*mousey = newmousey;*/
 		/*mousex = newmousex;*/
         /*for (int i = 0; i < 256; i++) {*/

src/game.c

@@ -1,4 +1,5 @@
 #include "game.h"
+#include <SDL2/SDL_mutex.h>
 
 #define FLOOR_THICKNESS 200 
 #define MAX_ROPE_GRAB_LEN 80000
@@ -211,6 +212,7 @@ player_st get_player(int x, int y) {
     // physics settings
     get_new_physics(&player.physics);
     player.physics->dynamics = true;
+    player.physics->lock = SDL_CreateMutex();
 
     player.physics->position.x = x;
     player.physics->position.y = y;
@@ -1051,9 +1053,9 @@ void advance_thing(Body * thing) {
     // get time delta
     struct timespec now = get_now();
     clock_gettime(CLOCK_MONOTONIC, &now);
-    if (now.tv_nsec >= 1000000000) {
-        now.tv_nsec -= 1000000000;
-    }
+    /*if (now.tv_nsec >= 1000000000) {*/
+        /*now.tv_nsec -= 1000000000;*/
+    /*}*/
 
     double time_delta = now.tv_nsec - thing->last_advance_time.tv_nsec;
 
@@ -1066,6 +1068,7 @@ void advance_thing(Body * thing) {
 
     // cap the time delta: simulatino will slow down
 //    printf("delta: %f\n", time_delta);
+    printf("ERROR too slow: %f\n", time_delta);
     if (time_delta > 19) {
         printf("ERROR too slow: %f\n", time_delta);
         time_delta = 19;
@@ -1122,7 +1125,6 @@ void advance_thing(Body * thing) {
             } else {
                 thing->vel.y += thing->obj_friction * friction.y; 
             }
-
         }
 
         /*double norm = 9.81 * thing->obj_mass;*/
@@ -1188,7 +1190,6 @@ void advance_thing(Body * thing) {
     
     // motors
     for (int i = 0; i < thing->num_motors; i++) {
-
         if (!get_motor_active(thing, i)) {
             continue;
         }
@@ -1247,11 +1248,16 @@ void advance_thing(Body * thing) {
         (*thing).vel.y = 0; 
     }
 
-    double oldx = thing->position.x;
-    double oldy = thing->position.y;
     thing->next_position.x +=  (thing->vel.x * 1/2 * (double)time_delta); 
     thing->next_position.y += (thing->vel.y * 1/2 * (double)time_delta); 
-    thing->position = thing->next_position;
+    if (thing->lock) {
+        if (SDL_LockMutex(thing->lock) == 0) {
+            thing->position = thing->next_position;
+            SDL_UnlockMutex(thing->lock);
+        }
+    } else {
+        thing->position = thing->next_position;
+    }
 
     if (!thing->collision_poly[0].y) {
         thing->updateCollisionPoly(thing);

src/game.h

@@ -1,6 +1,7 @@
 #ifndef _DEFGAME
 #define _DEFGAME 
 
+#include <time.h>
 #include "environment.h"
 #include "datastructures/datatypes.h"
 #include "vect.h"

src/main.c

@@ -20,7 +20,7 @@ struct SDL_Window* make_window(void) {
     } 
 
 
-    return SDL_CreateWindow("sdl_tester", 
+    return SDL_CreateWindow("space game", 
                                        SDL_WINDOWPOS_CENTERED, 
                                        SDL_WINDOWPOS_CENTERED, 
                                        0, 0, 
@@ -39,8 +39,8 @@ void redraw(struct SDL_Renderer * ren) {
 
 int physics_loop(void *ptr) {
     while (true) {
-        SDL_Delay(10);
         step(10);
+        SDL_Delay(2);
     }
 }
 
@@ -49,12 +49,12 @@ int game(void) {
     LOGLEVEL = DEBUG;
     STDOUTLEVEL = DEBUG;
 
-    SDL_SetHint( SDL_HINT_RENDER_SCALE_QUALITY, "2" );
+//    SDL_SetHint( SDL_HINT_RENDER_SCALE_QUALITY, "2" );
 
     logwrite(INFO, "Starting\n");
     SDL_Window * win = make_window();
-    SDL_Renderer * ren = SDL_CreateRenderer(win, -1, SDL_RENDERER_ACCELERATED);
-//            | SDL_RENDERER_PRESENTVSYNC);
+    SDL_Renderer * ren = SDL_CreateRenderer(win, -1, SDL_RENDERER_ACCELERATED
+            | SDL_RENDERER_PRESENTVSYNC);
 
     queue_for_cleanup(win, WINDOW);
     queue_for_cleanup(ren, RENDERER);
@@ -72,10 +72,12 @@ int game(void) {
     
     SDL_Thread *physics_thread;
     int ignore;
-//    physics_thread = SDL_CreateThread(physics_loop, "Physics", (void *)NULL);
 
     bool once = true;
     startgame(ren);
+
+    physics_thread = SDL_CreateThread(physics_loop, "Physics", (void *)NULL);
+
     while (!close)  {
 
         SDL_Event event; 
@@ -92,7 +94,7 @@ int game(void) {
             }
         }
         /* Redraw Screen */
-        step(10);
+//        step(10);
         redraw(ren);
     }
 

src/types.h

@@ -126,7 +126,7 @@ typedef struct BodyStruct{
     int num_strings;
     int max_strings;
     String *strings;
-
+    SDL_mutex *lock;
 } Body;
 
 typedef struct {