// procedure rmToFloor(int $pc)
// Move the lowest point of all objects in the selection so they sit exactly on the 
// top of the grid (global Y=0).
//
// params:
// int $pc - pivot control - (0 | 1 | 2)
// 0 = maintain object space (relative) pivot position
// 1 = maintain world space (global) pivot position
// 2 = center the pivot
// 
// usage: rmToFloor( 0 | 1 | 2);
// Copy this script to your maya scripts folder and source it and then make a selection of all
// the objects you want to move so they are sitting on the grid and enter the command
// rmToFloor 0 | 1 | 2;. 
//
// notes: 
//(1) This procedure depends on the mel command "exactWorldBoundingBox $obj" which 
// returns a float[] xmin ymin zmin xmax ymax zmax.  I use ymin to temporarily set
// the Y position of $obj's pivot so I can move it along Y such that it sits on the grid. 
// Moving each object to the grid has a constant complexity O(1).  This procedure has a 
// complexity of O(n), where n is the number of objects in the selection.
//
// [strike](2) this procedure moves the object but leaves the objects pivot in the same worldspace
// location.  I am not sure of the value of doing this and may want to either keep the
// local (relative) pivot location or just center the pivot.
//
// [strike](3) changed the script to maintain the relative pivot when the object is moved.
//
// (4) changed script to accept a pivot control parameter to control if the object object
// space or world space pivot is maintained or if the pivot is simply centered.
// 
// author: ctbram with valuable input from nextdesign
// date: 05292012
//
// change log:
// 05292012 - 
// (1) changed the program so the relative pivot of the object is maintained rather
// then the world pivot
// (2) added $pc (pivot control) parameter to control how the pivot is handled when the 
// object is moved.  0 = maintain object space, 1 = maintain world space, 2 = center pivot
//
// 05302012 -
// (1) Before computing the lower pivot using the bounding box I had to freetransformation
// on each object to zero out the rotation and align the bounding box to the global axis.
// Until I can find a better solution this is going to have to be lived with.
//
// (2) solved the freezetransform problem by simply executing an undo command after getting
// the $lowest value.  Only Commands are placed into the undo queue so exactWorldBoundingBox
// is a function and is not queued.  So once I have $lowest simply running undo, undoes the
// FreeTransformation.
//
global proc rmToFloor(int $pc)
{
    string $sel[] = `ls -sl`;
    string $obj;
    int $undoFlag = false;   // keep track of toggling the undo queue
    
    // make sure the pivot control parameter is 0 | 1 | 2.
    if (!(($pc == 0) || ($pc == 1) || ($pc == 2)))
         error("pivot control parameter must be (0 | 1 | 2).");

    for($obj in $sel)
    {
         float $osPivot[] = `xform -q -os -rp $obj`;            // save the object space (relative) pivot
         
    	 float $wsPivot[] = `xform -q -ws -rp $obj`;            // save world space $obj pivot
         
         // if the undo queue is off turn it on
         if (!(`undoInfo -q -st`))
         {
             $undoFlag = true;
             undoInfo -st true;
         } 
              
         select $obj; FreezeTransformations;    	        // ensure the bounding box is not rotated

         float $bbox[] = `exactWorldBoundingBox $obj`;          // get bounding box world space coords
         float $lowest = $bbox[1];                              // get lowest vert (ymin)
         
         undo;                                                  // undo the FreezeTransformation command

         // if the undo queue was off, turn it back off
         if ($undoFlag)
         {
             $undoflag = false;
             undoInfo -st false;
         }
         
         xform -ws -rp $wsPivot[0] $lowest $wsPivot[2] $obj;    // reset the pivot to the lowest point in world space
         move -rpr $wsPivot[0] 0 $wsPivot[2] $obj;              // move the object to the grid
         
         // handle the pivot based on the pivot control parameter $pc
    	 if ($pc == 0)
    	     xform -os -rp $osPivot[0] $osPivot[1] $osPivot[2] $obj;    // restore the object space (relative) pivot
    	 else if ($pc == 1)
    	     xform -ws -rp $wsPivot[0] $wsPivot[1] $wsPivot[2] $obj;    // restore the world space (relative) pivot
    	 else
    	     xform -cp $obj;    // center the pivot
    }
    
    select $sel;  // retore the original selection
}