// ----------------------------------------------------------------------------------------
// Name : RectPlacement.cpp
// Description : A class that fits subrectangles into a power-of-2 rectangle
// (C) Copyright 2000-2002 by Javier Arevalo
// This code is free to use and modify for all purposes
// ----------------------------------------------------------------------------------------
/*
* You have a bunch of rectangular pieces. You need to arrange them in a
* rectangular surface so that they don't overlap, keeping the total area of the
* rectangle as small as possible. This is fairly common when arranging characters
* in a bitmapped font, lightmaps for a 3D engine, and I guess other situations as
* well.
*
* The idea of this algorithm is that, as we add rectangles, we can pre-select
* "interesting" places where we can try to add the next rectangles. For optimal
* results, the rectangles should be added in order. I initially tried using area
* as a sorting criteria, but it didn't work well with very tall or very flat
* rectangles. I then tried using the longest dimension as a selector, and it
* worked much better. So much for intuition...
*
* These "interesting" places are just to the right and just below the currently
* added rectangle. The first rectangle, obviously, goes at the top left, the next
* one would go either to the right or below this one, and so on. It is a weird way
* to do it, but it seems to work very nicely.
*
* The way we search here is fairly brute-force, the fact being that for most off-
* line purposes the performance seems more than adequate. I have generated a
* japanese font with around 8500 characters and all the time was spent generating
* the bitmaps.
*
* Also, for all we care, we could grow the parent rectangle in a different way
* than power of two. It just happens that power of 2 is very convenient for
* graphics hardware textures.
*
* I'd be interested in hearing of other approaches to this problem. Make sure
* to post them on http://www.flipcode.com
*/
public RectPacker(int _w, int _h)
{
size = new PackerRect(0, 0, _w, _h, null);
vRects = new List <PackerRect>();
vPositions = new List <PackerPos>();
vPositions.Add(new PackerPos(0, 0));
area = 0;
}
// --------------------------------------------------------------------------------
// Name : AddRect
// Description : Add the given rect and updates anchor points
// --------------------------------------------------------------------------------
public void addRect(PackerRect r)
{
vRects.Add(r);
area += r.w * r.h;
// Add two new anchor points
addPosition(new PackerPos(r.x, r.y + r.h));
addPosition(new PackerPos(r.x + r.w, r.y));
}
// --------------------------------------------------------------------------------
// Name : AddAtEmptySpot
// Description : Add the given rectangle
// --------------------------------------------------------------------------------
public bool addAtEmptySpot(PackerRect r)
{
// Find a valid spot among available anchors.
bool bFound = false;
int pos = 0;
foreach (PackerPos it in vPositions)
{
PackerRect rect = new PackerRect(it.x, it.y, r.w, r.h, r.obj);
if (isFree(rect))
{
r = rect;
bFound = true;
break; // Don't let the loop increase the iterator.
}
pos++;
}
if (bFound)
{
// Remove the used anchor point
vPositions.RemoveAt(pos);
// Sometimes, anchors end up displaced from the optimal position
// due to irregular sizes of the subrects.
// So, try to adjut it up & left as much as possible.
int x, y;
for (x = 1; x <= r.x; x++)
{
if (!isFree(new PackerRect(r.x - x, r.y, r.w, r.h, r.obj)))
{
break;
}
}
for (y = 1; y <= r.y; y++)
{
if (!isFree(new PackerRect(r.x, r.y - y, r.w, r.h, r.obj)))
{
break;
}
}
if (y > x)
{
r.y -= y - 1;
}
else
{
r.x -= x - 1;
}
addRect(r);
}
return(bFound);
}
// --------------------------------------------------------------------------------
// Name : IsFree
// Description : Check if the given rectangle is partially or totally used
// --------------------------------------------------------------------------------
public bool isFree(PackerRect r)
{
if (!size.containsRect(r))
{
return(false);
}
foreach (PackerRect it in vRects)
{
if (it.intersects(r))
{
return(false);
}
}
return(true);
}
// Greater rect area. Not as good as the next heuristic
// static bool Greater(const TRect &a, const TRect &b) { return a.w*a.h > b.w*b.h; }
// Greater size in at least one dim.
public static bool greater(PackerRect a, PackerRect b)
{
return((a.w > b.w && a.w > b.h) ||
(a.h > b.w && a.h > b.h));
}
public bool intersects(PackerRect r)
{
return(w > 0 && h > 0 && r.w > 0 && r.h > 0 &&
((r.x + r.w) > x && r.x < (x + w) &&
(r.y + r.h) > y && r.y < (y + h)));
}
public bool containsRect(PackerRect r)
{
return(r.x >= x && r.y >= y &&
(r.x + r.w) <= (x + w) && (r.y + r.h) <= (y + h));
}
// --------------------------------------------------------------------------------
// Name : AddAtEmptySpotAutoGrow
// Description : Add a rectangle of the given size, growing our area if needed
// Area grows only until the max given.
// Returns the placement of the rect in the rect's x,y coords
// --------------------------------------------------------------------------------
public bool addAtEmptySpotAutoGrow(PackerRect pRect, int maxW, int maxH)
{
if (pRect.w <= 0)
{
return(true);
}
int orgW = size.w;
int orgH = size.h;
// Try to add it in the existing space
while (!addAtEmptySpot(pRect))
{
int pw = size.w;
int ph = size.h;
// Sanity check - if area is complete.
if (pw >= maxW && ph >= maxH)
{
size.w = orgW;
size.h = orgH;
return(false);
}
// Try growing the smallest dim
if (pw < maxW && (pw < ph || ((pw == ph) && (pRect.w >= pRect.h))))
{
size.w = Math.Min(maxW, pw + 10); //*2;
}
else
{
size.h = Math.Min(maxH, ph + 10); //*2;
}
if (addAtEmptySpot(pRect))
{
break;
}
// Try growing the other dim instead
if (pw != size.w)
{
size.w = pw;
if (ph < maxW)
{
size.h = Math.Min(maxH, ph + 10); //*2;
}
}
else
{
size.h = ph;
if (pw < maxW)
{
size.w = Math.Min(maxW, pw + 10); //*2;
}
}
if (pw != size.w || ph != size.h)
{
if (addAtEmptySpot(pRect))
{
break;
}
}
// Grow both if possible, and reloop.
size.w = pw;
size.h = ph;
if (pw < maxW)
{
size.w = Math.Min(maxW, pw + 10); //*2;
}
if (ph < maxH)
{
size.h = Math.Min(maxH, ph + 10); //*2;
}
}
return(true);
}
