From 8b7846e46ebcd43a4196d834e93332a3acc5ac1e Mon Sep 17 00:00:00 2001
From: Bruce Hill <bruce@bruce-hill.com>
Date: Mon, 18 Mar 2019 17:37:37 -0700
Subject: [PATCH] Now 'c' can clear instead of command line argument '-Z'

---
 README.md | 10 +++++++---
 conway.c  | 27 +++++++++++++--------------
 2 files changed, 20 insertions(+), 17 deletions(-)

diff --git a/README.md b/README.md
index c8449ae..b75a68c 100644
--- a/README.md
+++ b/README.md
@@ -6,11 +6,15 @@ Command line flags:
 
 * `-S[0-8]*` the rules for when an alive cell survives
 * `-B[0-8]*` the rules for when a new cell is born
-* `-Z` start the canvas with all dead cells (zeroed out)
 * `-A[0-256]` provide a color for alive cells
 * `-D[0-256]` provide a color for dead cells
 
 Some interesting rulesets can be found in [this list](http://psoup.math.wisc.edu/mcell/rullex_life.html).
 
-You can draw with the mouse and press space to toggle drawing mode (default: create living cells).
-Pressing `p` will toggle play/pause and pressing escape or `q` will quit.
+Actions:
+
+* Mouse: draw (by default: create new cells)
+* Space: toggle mouse mode between create/destroy
+* `p`: toggle play/pause
+* `q` or Escape: quit
+* `c`: clear the world
diff --git a/conway.c b/conway.c
index 023c7a7..ad03eb8 100644
--- a/conway.c
+++ b/conway.c
@@ -9,7 +9,7 @@
 #define CELL(cells, x, y) cells[((y) % H)*W + ((x) % W)]
 
 static char rules[2][9] = {{0,0,0,1,0,0,0,0,0}, {0,0,1,1,0,0,0,0,0}};
-static int W, H, DEAD = 0, ALIVE = 8;
+static int W, H, DEAD = 0, ALIVE = 7;
 
 static void update(const char *cells, char *future_cells)
 {
@@ -20,19 +20,17 @@ static void update(const char *cells, char *future_cells)
                 + CELL(cells,x-1,y) + CELL(cells,x+1,y)
                 + CELL(cells,x-1,y+1) + CELL(cells,x,y+1) + CELL(cells,x+1,y+1);
             CELL(future_cells, x, y) = rules[CELL(cells, x, y)][neighbors];
-            if (CELL(future_cells, x, y) != CELL(cells, x, y)) {
-                tb_change_cell(2*x, y, ' ', 0, CELL(future_cells, x, y) ? ALIVE : DEAD);
-                tb_change_cell(2*x+1, y, ' ', 0, CELL(future_cells, x, y) ? ALIVE : DEAD);
-            }
+            tb_change_cell(2*x, y, ' ', 0, CELL(future_cells, x, y) ? ALIVE : DEAD);
+            tb_change_cell(2*x+1, y, ' ', 0, CELL(future_cells, x, y) ? ALIVE : DEAD);
         }
     }
 }
 
 int main(int argc, char **argv) {
-    int randomize = 1;
     for (int i = 1; i < argc; i++) {
         if (strcmp(argv[i], "--help") == 0) {
-            printf("Conway's Game of Life Viewer\nUsage: conway [-Z] [-S012345678] [-B012345678]\n");
+          usage:
+            printf("Conway's Game of Life Viewer\nUsage: conway [-S<survival rules>] [-B<birth rules>] [-A<alive color>] [-D<dead color>]\n");
             return 0;
         } else if (strncmp(argv[i], "-B", 2) == 0) {
             memset(rules[0], 0, sizeof(rules[0]));
@@ -58,8 +56,8 @@ int main(int argc, char **argv) {
                 fprintf(stderr, "Colors must be between 0-255\n");
                 return 1;
             }
-        } else if (strcmp(argv[i], "-Z") == 0) {
-            randomize = 0;
+        } else {
+            goto usage;
         }
     }
 
@@ -78,13 +76,12 @@ int main(int argc, char **argv) {
     W = tb_width()/2, H = tb_height();
     buffers[0] = calloc(W*H, sizeof(char));
     buffers[1] = calloc(W*H, sizeof(char));
-    if (randomize)
-        for (int x = 0; x < W; x++)
-            for (int y = 0; y < H; y++)
-                CELL(buffers[flipflop], x, y) = random() % 2;
+    for (int x = 0; x < W; x++)
+        for (int y = 0; y < H; y++)
+            CELL(buffers[flipflop], x, y) = random() % 2;
 
     int draw_mode = 1, paused = 0;
-    tb_set_clear_attributes(ALIVE, DEAD);
+    tb_set_clear_attributes(0, DEAD);
     tb_clear();
     while (1) {
         if (!paused) {
@@ -110,6 +107,8 @@ int main(int argc, char **argv) {
                         goto done;
                     else if (ev.ch == 'p')
                         paused = !paused;
+                    else if (ev.ch == 'c')
+                        memset(buffers[flipflop], 0, W*H);
                     else if (ev.key == TB_KEY_SPACE)
                         draw_mode = !draw_mode;
                     break;