From 318bdfb9c0cfdaf83465720f0e34a9acc6a66ce1 Mon Sep 17 00:00:00 2001
From: Bruce Hill <bruce@bruce-hill.com>
Date: Mon, 18 Mar 2019 16:48:54 -0700
Subject: [PATCH] Added zero-filled option for blank canvas.

---
 README.md |  6 +++++-
 conway.c  | 12 ++++++++----
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/README.md b/README.md
index 358a529..82c8237 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,7 @@
 # Conway
 A termbox program for running Conway's Game of Life.
-Different rulesets can be used with `conway -S23 -B3` syntax.
+
+# Usage
+Different rulesets can be provided with the `conway -S23 -B3` flags. To start
+with a blank canvas instead of a randomized canvas, use `-Z`.
+
diff --git a/conway.c b/conway.c
index 6b05a2b..4f8335c 100644
--- a/conway.c
+++ b/conway.c
@@ -29,9 +29,10 @@ static void update(const char *cells, char *future_cells)
 }
 
 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 [-S012345678] [-B012345678]\n");
+            printf("Conway's Game of Life Viewer\nUsage: conway [-Z] [-S012345678] [-B012345678]\n");
             return 0;
         } else if (strncmp(argv[i], "-B", 2) == 0) {
             memset(rules[0], 0, sizeof(rules[0]));
@@ -45,6 +46,8 @@ int main(int argc, char **argv) {
                 if ('0' <= *p && *p <= '8')
                     rules[1][*p - '0'] = 1;
             }
+        } else if (strcmp(argv[i], "-Z") == 0) {
+            randomize = 0;
         }
     }
 
@@ -62,9 +65,10 @@ 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));
-    for (int x = 0; x < W; x++)
-        for (int y = 0; y < H; y++)
-            CELL(buffers[flipflop], x, y) = random() % 2;
+    if (randomize)
+        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;
     tb_clear();