$NetBSD: patch-aa,v 1.2 2008/06/02 16:57:37 drochner Exp $

--- src/map/tileitem.cpp.orig	2008-05-16 00:47:34.000000000 +0200
+++ src/map/tileitem.cpp
@@ -136,40 +136,42 @@ void TileItem_AlphaSoftware::Dig(const P
   buf += y * line_size;
 
   //Empties each line of the tile horizontaly that are in the circle
-  while ( (uint) y <= center.y + radius + EXPLOSION_BORDER_SIZE&& y < CELL_SIZE.y )
+  for (; (uint)y <= center.y + radius + EXPLOSION_BORDER_SIZE && y < CELL_SIZE.y;
+       buf += line_size, y++)
   {
     //Abscisse distance from the center of the circle to the circle
     int dac = center.y - y;
 
-    //Angle on the circle
-    float angle = asin( (float)dac / (float)radius);
+    //Darken the border of the removed ground
+    int bstart_x, bend_x, blenght;
+    blenght = lrint(sqrt((radius + EXPLOSION_BORDER_SIZE) * (radius + EXPLOSION_BORDER_SIZE)
+			 - dac * dac));
+
+    if ((uint)abs(dac) > radius) {
+	bstart_x = center.x - blenght;
+	bend_x = center.x + blenght;
+	Darken(bstart_x, bend_x, buf, bpp);
+	continue;
+    }
 
     //Zone of the line which needs to be emptied
-    int start_x, end_x, lenght;
-    lenght = (int) ((float) radius * cos (angle));
-    lenght = lenght > 0 ? lenght : - lenght;
-    start_x = center.x - lenght;
-    lenght *= 2;
-    end_x = start_x + lenght;
-    Empty(start_x, end_x, buf, bpp);
+    int lenght;
+    lenght = lrint(sqrt(radius * radius - dac * dac));
 
-    //Darken the border of the removed ground
     // Left half of the circle
-    int bstart_x, bend_x, blenght;
-    angle = asin( (float)dac / (float)(radius + EXPLOSION_BORDER_SIZE));
-    blenght = (int) ((float) (radius + EXPLOSION_BORDER_SIZE) * cos (angle));
-    blenght = blenght > 0 ? blenght : - blenght;
     bstart_x = center.x - blenght;
-    bend_x = bstart_x + (blenght - lenght/2);
+    bend_x = center.x - lenght;
     Darken(bstart_x, bend_x, buf, bpp);
 
     // Right half of the circle
-    bstart_x = center.x + lenght/2 + 1;
-    bend_x = bstart_x + (blenght - lenght/2);
+    bstart_x = center.x + lenght;
+    bend_x = center.x + blenght;
     Darken(bstart_x, bend_x, buf, bpp);
 
-    buf += line_size;
-    y++;
+    int start_x, end_x;
+    start_x = center.x - lenght;
+    end_x = center.x + lenght;
+    Empty(start_x, end_x, buf, bpp);
   }
 }