1 files changed, 65 insertions, 0 deletions
diff --git a/src/cave_type.hpp b/src/cave_type.hpp
new file mode 100644
index 00000000..958ace1d
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+++ b/src/cave_type.hpp
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+#pragma once
+
+#include "h-basic.h"
+
+#include <cassert>
+#include <vector>
+
+/**
+ * A single "grid" in a Cave.
+ *
+ * Note that several aspects of the code restrict the actual cave
+ * to a max size of 256 by 256.  In partcular, locations are often
+ * saved as bytes, limiting each coordinate to the 0-255 range.
+ *
+ * The "o_idx" and "m_idx" fields are very interesting.  There are
+ * many places in the code where we need quick access to the actual
+ * monster or object(s) in a given cave grid.  The easiest way to
+ * do this is to simply keep the index of the monster and object
+ * (if any) with the grid, but this takes 198*66*4 bytes of memory.
+ * Several other methods come to mind, which require only half this
+ * amound of memory, but they all seem rather complicated, and would
+ * probably add enough code that the savings would be lost.  So for
+ * these reasons, we simply store an index into the "o_list" and
+ * "m_list" arrays, using "zero" when no monster/object is present.
+ *
+ * Note that "o_idx" is the index of the top object in a stack of
+ * objects, using the "next_o_idx" field of objects to create the
+ * singly linked list of objects.  If "o_idx" is zero then there
+ * are no objects in the grid.
+ */
+struct cave_type
+{
+	u16b info = 0;	                       /* Hack -- cave flags */
+
+	byte feat = 0;                         /* Hack -- feature type */
+
+	std::vector<s16b> o_idxs { };          /* Indexes of objects in this grid */
+
+	s16b m_idx = 0;                        /* Monster in this grid */
+
+	s16b t_idx = 0;                        /* trap index (in t_list) or zero       */
+
+	s16b special = 0;                      /* Special cave info */
+	s16b special2 = 0;                     /* Special cave info */
+
+	s16b inscription = 0;                  /* Inscription of the grid */
+
+	byte mana = 0;                         /* Magical energy of the grid */
+
+	byte mimic = 0;                        /* Feature to mimic */
+
+	byte cost = 0;                         /* Hack -- cost of flowing */
+	byte when = 0;                         /* Hack -- when cost was computed */
+
+	s16b effect = 0;                       /* The lasting effects */
+
+	/**
+	 * @brief wipe the object's state
+	 */
+	void wipe() {
+		/* Reset to defaults */
+		*this = cave_type();
+	}
+
+};