From c234b317843200c5059c57c16621fb722f579fb0 Mon Sep 17 00:00:00 2001
From: P. J. McDermott <pj@pehjota.net>
Date: Sun, 08 Aug 2021 16:41:14 -0400
Subject: game: Implement fog of war

---
(limited to 'src')

diff --git a/src/defs.h b/src/defs.h
index a200ad1..51d76f3 100644
--- a/src/defs.h
+++ b/src/defs.h
@@ -80,6 +80,10 @@
 #define MF_COLOR_CHKM_G 0x00
 #define MF_COLOR_CHKM_B 0x00
 #define MF_COLOR_CHKM_A 0xFF
+#define MF_COLOR_FOGW_R 0x2F  /* Fog of war color */
+#define MF_COLOR_FOGW_G 0x2F
+#define MF_COLOR_FOGW_B 0x2F
+#define MF_COLOR_FOGW_A 0xFF
 #define MF_COLOR_PLYR_R 0x00  /* Player color */
 #define MF_COLOR_PLYR_G 0xAF
 #define MF_COLOR_PLYR_B 0x7F
diff --git a/src/game.c b/src/game.c
index e336c03..433227f 100644
--- a/src/game.c
+++ b/src/game.c
@@ -62,6 +62,73 @@ _mf_game_form(SDL_Renderer *renderer, TTF_Font *text_font,
 			);
 }
 
+static int
+_mf_game_fow(SDL_Renderer *renderer, struct mf_maze *maze,
+		struct mf_player *player, int cw)
+{
+	int      x1;
+	int      y1;
+	int      travel;
+	int      dx;
+	int      dy;
+	int      x2;
+	int      y2;
+	SDL_Rect rect;
+
+	if (SDL_SetRenderDrawColor(renderer,
+				MF_COLOR_FOGW_R, MF_COLOR_FOGW_G,
+				MF_COLOR_FOGW_B, MF_COLOR_FOGW_A) < 0) {
+		SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, \
+				"Couldn't render fog: %s", \
+				SDL_GetError()); \
+		return -1; \
+	}
+
+	mf_player_get_vector(player, &x1, &y1, &travel, &dx, &dy);
+	x2 = x1, y2 = y1;
+	while (!mf_maze_is_wall(maze, dx >= 0 ? x2 : x1, dy >= 0 ? y2 : y1,
+				dx, dy)) {
+		if (dx >= 0) x2 += dx;
+		else         x1 += dx;
+		if (dy >= 0) y2 += dy;
+		else         y1 += dy;
+	}
+	++x2, ++y2;
+	x1 *= cw, y1 *= cw, x2 *= cw, y2 *= cw;
+	if (dx >= 0) x1 += travel * dx;
+	else         x2 += travel * dx;
+	if (dy >= 0) y1 += travel * dy;
+	else         y2 += travel * dy;
+	++x2, ++y2;
+
+#define mf_game_w_ MF_WINDOW_H
+#define mf_game_h_ MF_WINDOW_H
+#define mf_game_render_() \
+	do { \
+		if (SDL_RenderFillRect(renderer, &rect) < 0) { \
+			SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, \
+					"Couldn't render fog: %s", \
+					SDL_GetError()); \
+			return -1; \
+		} \
+	} while (0)
+
+	rect.x=  0, rect.y= 0,  rect.w= x1,            rect.h= mf_game_h_;
+	mf_game_render_();
+	rect.x= x1, rect.y= 0,  rect.w= x2-x1,         rect.h= y1;
+	mf_game_render_();
+	rect.x= x1, rect.y= y2, rect.w= x2-x1,         rect.h= mf_game_h_-y2;
+	mf_game_render_();
+	rect.x= x2, rect.y= 0,  rect.w= mf_game_w_-x2, rect.h= mf_game_h_;
+	mf_game_render_();
+
+#undef mf_game_w_
+#undef mf_game_h_
+#undef mf_game_render_
+
+	return 0;
+}
+
 int
 mf_game(long seed, int size, int fow, int reveal, SDL_Renderer *renderer)
 {
@@ -153,15 +220,19 @@ mf_game(long seed, int size, int fow, int reveal, SDL_Renderer *renderer)
 				MF_COLOR_BACK_R, MF_COLOR_BACK_G,
 				MF_COLOR_BACK_B, MF_COLOR_BACK_A);
 		SDL_RenderClear(renderer);
-		mf_maze_render(maze, renderer, &maze_color, MF_WINDOW_H / size);
 		mf_player_render(player, renderer);
+		if (fow == SDL_TRUE && _mf_game_fow(renderer, maze, player,
+					MF_WINDOW_H / size) < 0) {
+			goto err;
+		}
+		mf_maze_render(maze, renderer, &maze_color, MF_WINDOW_H / size);
 		secs = (beg - game.beg) / 1000;
 		if (sprintf(game.time_buf, "%02d:%02d", secs / 60, secs % 60)
 				< 0) {
 			SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
 					"Couldn't allocate string: %s",
 					strerror(errno));
-			return -1;
+			goto err;
 		}
 		mftk_text_set_value(game.timer, game.time_buf);
 		mftk_window_render(win, renderer);
--
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