optimized drawing of player and balls, fixing flickering on some terminals

.gitignore

@@ -0,0 +1,2 @@
+snek
+*.o

ball.c

@@ -9,6 +9,8 @@
 void init_ball(BALL* b, int x, int y, char dir, int value) {
 	b -> position.x = x;
 	b -> position.y = y;
+	b -> old_position.x = x;
+	b -> old_position.y = y;
 	b -> direction = dir;
 	b -> value = value;
 	b -> color = value + 2;
@@ -80,6 +82,9 @@ void move_ball(FIELD* f, int i) {
 	POINT direction_vector;
 	direction_to_point(&direction_vector, b -> direction);
 	add_to_point(&direction_vector, pos); 
+
+	b -> old_position.x = b -> position.x;
+	b -> old_position.y = b -> position.y;
 	
 	bounce(b, f);
 	

field.c

@@ -96,3 +96,25 @@ void redraw_field(FIELD* f) {
 	draw_player(f);
 	wrefresh(f -> win);
 }
+
+void update_ballpos(FIELD* f) {
+	for (int i = 0; i < f -> ball_count; i++) {
+		BALL* b = f -> balls[i];
+		wattrset(f -> win, COLOR_PAIR(7));
+		mvwprintw(f -> win, b -> old_position.y, b -> old_position.x * 2, "  ");
+		wattrset(f -> win, COLOR_PAIR(b -> color));
+		mvwprintw(f -> win, b -> position.y, b -> position.x * 2, "  ");
+	}
+	wrefresh(f -> win);
+}
+void update_playerpos(FIELD* f) {
+	PLAYER* player = f -> player;
+	wattrset(f -> win, COLOR_PAIR(7));
+	mvwprintw(f -> win, player -> old_tail -> y, player -> old_tail -> x * 2, "  ");
+	wattrset(f -> win, COLOR_PAIR(2));
+	mvwprintw(f -> win,
+			player -> body[player -> head_ptr] -> y,
+			player -> body[player -> head_ptr] -> x * 2,
+			"  ");
+	wrefresh(f -> win);
+}

field.h

@@ -5,6 +5,8 @@ void redraw_field(FIELD* f);
 void init_field(FIELD* f, int width, int height, GAME_STATE* state);
 void add_ball(FIELD* f, int max_value);
 void destroy_field(FIELD* f);
+void update_ballpos(FIELD* f);
+void update_playerpos(FIELD* f);
 
 
 #endif

game.c

@@ -54,7 +54,6 @@ void play_game(GAME_STATE* state) {
 	FD_ZERO(&inputs);
 	FD_SET(0, &inputs);
 	
-	int redraw = 0;
 	char player_tick = 0;
 	while(1) {
 		if (state -> status) {
@@ -69,23 +68,19 @@ void play_game(GAME_STATE* state) {
 		
 		int sel_ret = select(FD_SETSIZE, &test_fds, (fd_set *) 0, (fd_set *) 0, &timeout);
 		
-		redraw = 0;
 		if (sel_ret == 0) {
 			player_tick = (player_tick + 1) % 3;
-			redraw = 1;
 			move_balls(f);
+			update_ballpos(f);
 			
 			if (!player_tick) {
 				move_player(f);
-				redraw = 1;
+				update_playerpos(f);
 			}
 			timeout.tv_sec = 0;
 			timeout.tv_usec = 50000;
 		}
 		
-		if (redraw) {
-			redraw_field(f);
-		}
 	}
 	
 	free(f);

game.h

@@ -10,6 +10,7 @@ typedef struct {
 typedef struct {
 	char direction;
 	POINT position;
+	POINT old_position;
 	int value;
 	char color;
 	int move_tick;
@@ -21,6 +22,8 @@ typedef struct {
 	
 	int next_head_dir_x;
 	int next_head_dir_y;
+
+	POINT* old_tail;
 	
 	POINT** body;
 	int head_ptr;

main.c

@@ -20,6 +20,7 @@ int main(int argc, char** argv) {
 	init_pair(4, COLOR_WHITE, COLOR_RED);
 	init_pair(5, COLOR_WHITE, COLOR_BLUE);
 	init_pair(6, COLOR_WHITE, COLOR_YELLOW);
+	init_pair(7, COLOR_WHITE, COLOR_BLACK);
 	
 	srandom(time( (time_t *) 0 ));
 	

player.c

@@ -64,7 +64,8 @@ void move_player(FIELD* field) {
 	
 	POINT* oldhead = player -> body[player -> head_ptr];
 	player -> head_ptr = (player -> head_ptr + 1) % player -> length;
-	free(player -> body[player -> head_ptr]);
+	free(player -> old_tail);
+	player -> old_tail = player -> body[player -> head_ptr];
 	POINT* newhead = malloc(sizeof(POINT));
 	newhead -> x = oldhead -> x + player -> head_dir_x;
 	newhead -> y = oldhead -> y + player -> head_dir_y;