Relative sizing in UI - bug?
by Keith Johnston · in Torque Game Engine · 02/17/2004 (5:52 am) · 2 replies
I've recently switched to using relative sizing / positioning for all the controls in the UI. However, sometimes the sizes seem to change in an odd way, even in the same resolution - buttons become skewed, for example. Is this a bug? I'm using the 1.2 release - maybe this has been fixed in a later release?
Torque Owner Andy
The cause is related to the position and extant information being stored as integers and can rapidly accumulate errors due to rounding. In my case, I discovered it while checking my layout with the Gui editor and switching resolutions.
I had 48x48 bitmap buttons at 1024x768, but after switching resolutions 1024x768 --> 800x600 --> 640x480 --> 1024x768 my buttons were various permutations ranging from 48x49 through 51x50 or so.
I have a simple patch that uses floating-point and rounding during the horizontal and vertical rescale computation. It reduces the problem somewhat, but doesn't really eliminate it.
A true fix looks like it could be rather invasive.
Here's the diff relative to 1.2.1 (sorry if it gets whitespace mangled):
Index: torque/engine/gui/guiControl.cc =================================================================== RCS file: /home/cvsroot/garagegames/torque/engine/gui/guiControl.cc,v retrieving revision 1.1.1.2 retrieving revision 1.1.1.2.2.1 diff -a -u -r1.1.1.2 -r1.1.1.2.2.1 --- torque/engine/gui/guiControl.cc 2004/02/06 21:03:44 1.1.1.2 +++ torque/engine/gui/guiControl.cc 2004/03/04 16:57:46 1.1.1.2.2.1 @@ -252,8 +252,8 @@ newPosition.x += deltaX; else if (mHorizSizing == horizResizeRelative && oldParentExtent.x != 0) { - S32 newLeft = (newPosition.x * newParentExtent.x) / oldParentExtent.x; - S32 newRight = ((newPosition.x + newExtent.x) * newParentExtent.x) / oldParentExtent.x; + S32 newLeft = (S32) (((newPosition.x * newParentExtent.x) / (F64) oldParentExtent.x) + 0.5); + S32 newRight = (S32) ((((newPosition.x + newExtent.x) * newParentExtent.x) / (F64) oldParentExtent.x) + 0.5); newPosition.x = newLeft; newExtent.x = newRight - newLeft; @@ -268,8 +268,8 @@ else if(mVertSizing == vertResizeRelative && oldParentExtent.y != 0) { - S32 newTop = (newPosition.y * newParentExtent.y) / oldParentExtent.y; - S32 newBottom = ((newPosition.y + newExtent.y) * newParentExtent.y) / oldParentExtent.y; + S32 newTop = (S32) (((newPosition.y * newParentExtent.y) / (F64) oldParentExtent.y) + 0.5); + S32 newBottom = (S32) ((((newPosition.y + newExtent.y) * newParentExtent.y) / (F64) oldParentExtent.y) + 0.5); newPosition.y = newTop; newExtent.y = newBottom - newTop;