Update

procgen.md

@@ -215,4 +215,112 @@ int main(void)
 }
 ```
 
+Now let's take a look at some iterative algorithm: an extremely simple dungeon generator. All it's going to do is just randomly choose a cardinal direction (up, right, down, left), draw a line of random length, and repeat the same from the line's endpoint, until predefined number of lines has been drawn. Here is the C code:
+
+```
+#include <stdio.h>
+
+#define W 30            // world width
+#define H 30            // world height
+
+char world[H * W];      // 2D world array
+
+unsigned int r = 12345; // random seed here
+
+unsigned int random()
+{
+  r = r * 321 + 29;
+  return r >> 4;
+}
+
+void generateWorld()
+{
+  int steps = 100;      // draw this many lines
+  int pos = 0;
+  int add = 1;          // movement offset
+  int nextLineIn = 1;
+
+  for (int i = 0; i < H * W; ++i)
+    world[i] = ' ';
+
+  while (steps)
+  {
+    world[pos] = 'X';
+    nextLineIn--;
+
+    int nextPos = pos + add;
+
+    if (nextPos < 0 || nextPos >= W * H || // going over world edge?
+      (add == 1 && nextPos % W == 0) ||
+      (add == -1 && nextPos % W == W - 1))
+      nextLineIn = 0;
+    else
+      pos = nextPos;
+
+    if (nextLineIn <= 0)
+    {
+      steps--;
+      nextLineIn = W / 5 + random() % (W / 3);
+      add = (random() & 0x10) ? W : 1;
+ 
+      if (rand() & 0x80)
+        add *= -1;
+    }
+  }
+}
+
+int main(void)
+{
+  generateWorld();
+
+  for (int i = 0; i < H * W; ++i) // draw
+  {
+    char c = world[i];
+
+    putchar(c);
+    putchar(c);
+
+    if ((i + 1) % W == 0)
+      putchar('\n');
+  }
+
+  return 0;
+}
+```
+
+And here is one possible output of the program:
+
+```
+XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
+XXXX  XXXX              XX  XXXXXXXXXXXXXXXXXXXXXXXXXXXXX
+XXXX  XXXX  XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
+XXXX  XXXX  XX          XX  XXXX  XX          XX        X
+XXXX  XXXX  XX          XX  XXXX  XX          XX        X
+XXXX  XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX          XX        X
+XXXX  XXXX  XX      XX  XX  XXXX  XX          XX        X
+XXXX  XXXX  XX      XX  XX  XXXX  XX                    X
+XXXX  XXXX  XX      XX  XX  XXXX  XX                    X
+XXXX  XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX                    X
+XX      XX  XX      XX  XX  XXXX  XX                    X
+XX      XX  XX      XX  XX  XXXX  XX                    X
+XXXXXXXXXXXXXX      XX  XX  XXXX                        X
+XX      XX  XX      XX  XX  XXXX                        X
+XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX                        X
+XXXXXXXXXXXXXXXXXXXXXX        XX                        X
+XX  XX      XX      XX        XX                        X
+XX  XX      XX      XX        XX                        X
+XX  XX      XX      XX        XX                        X
+XX  XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX                    X
+XX  XX      XX      XX        XX                        X
+XX  XX      XX      XX        XX                        X
+XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX        X
+XX  XX      XX      XX        XX              XX        X
+XX  XX      XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
+XX  XX      XX      XX        XX              XX        X
+    XX      XX      XX        XXXXXXXXXXXXXXXXXXXXXXXXXXX
+    XX      XX      XX                        XX
+            XX      XX                        XX
+            XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX  XX
+```
+
 TODO: some example with noise