diff --git a/doomtypes.h b/doomtypes.h
index ca5e822..36f340a 100644
--- a/doomtypes.h
+++ b/doomtypes.h
@@ -108,6 +108,17 @@ typedef enum
     RF_CLOSED   =16,     // Line blocks view
 } r_flags;
 
+
+/* Bounding box coordinate storage. */
+enum
+{
+  BOXTOP,
+  BOXBOTTOM,
+  BOXLEFT,
+  BOXRIGHT
+};  /* bbox coordinates */
+
+
 typedef struct line_s
 {
     vertex_t v1;
@@ -117,6 +128,8 @@ typedef struct line_s
 
     quint16 sidenum[2];        // Visual appearance: SideDefs.
 
+    fixed_t bbox[4];        //Line bounding box.
+
     quint16 flags;           // Animation related.
     qint16 special;
     qint16 tag;
diff --git a/wadprocessor.cpp b/wadprocessor.cpp
index 99fb8da..616922f 100644
--- a/wadprocessor.cpp
+++ b/wadprocessor.cpp
@@ -174,6 +174,12 @@ bool WadProcessor::ProcessLines(quint32 lumpNum)
         newLines[i].sidenum[0] = oldLines[i].sidenum[0];
         newLines[i].sidenum[1] = oldLines[i].sidenum[1];
 
+        newLines[i].bbox[BOXLEFT] = (newLines[i].v1.x < newLines[i].v2.x ? newLines[i].v1.x : newLines[i].v2.x);
+        newLines[i].bbox[BOXRIGHT] = (newLines[i].v1.x < newLines[i].v2.x ? newLines[i].v2.x : newLines[i].v1.x);
+
+        newLines[i].bbox[BOXTOP] = (newLines[i].v1.y < newLines[i].v2.y ? newLines[i].v2.y : newLines[i].v1.y);
+        newLines[i].bbox[BOXBOTTOM] = (newLines[i].v1.y < newLines[i].v2.y ? newLines[i].v1.y : newLines[i].v2.y);
+
         newLines[i].lineno = i;
 
     }