1 files changed, 59 insertions, 0 deletions

diff --git a/js/lib/geom/geom-obj.js b/js/lib/geom/geom-obj.js
index 2f5559a7..4efa5d60 100755
--- a/js/lib/geom/geom-obj.js
+++ b/js/lib/geom/geom-obj.js
@@ -415,6 +415,65 @@ var GeomObj = function GLGeomObj()
         }
     };
 
+
+        this.getGLCenter = function()
+        {
+                // get the normalized device coordinates (NDC) for
+                // all position and dimensions.
+                var world = this.getWorld();
+                var     vpw = world.getViewportWidth(),  vph = world.getViewportHeight();
+                var     xNDC = 2*this._xOffset/vpw,  yNDC = -2*this._yOffset/vph;
+
+                var aspect = world.getAspect();
+                var zn = world.getZNear(),  zf = world.getZFar();
+                var     t = zn * Math.tan(world.getFOV() * Math.PI / 360.0),
+                        b = -t,
+                        r = aspect*t,
+                        l = -r;
+
+                // calculate the object coordinates from their NDC coordinates
+                var z = -world.getViewDistance();
+
+                // unproject to get the position of the origin in GL
+                var x = -z*(r-l)/(2.0*zn)*xNDC,
+                        y = -z*(t-b)/(2.0*zn)*yNDC;
+                z = 0.0;
+
+                // transform by the object's transformation matrix
+                var ctr = MathUtils.transformPoint( [x, y, z], this.getMatrix() );
+
+                return ctr;
+        };
+
+        this.preViewToGL = function( preViewPt )
+        {
+                // get the normalized device coordinates (NDC) for
+                // all position and dimensions.
+                var world = this.getWorld();
+                var     vpw = world.getViewportWidth(),  vph = world.getViewportHeight();
+                var     xNDC = 2*preViewPt[0]/vpw,  yNDC = -2*preViewPt[1]/vph;
+
+                var aspect = world.getAspect();
+                var zn = world.getZNear(),  zf = world.getZFar();
+                var     t = zn * Math.tan(world.getFOV() * Math.PI / 360.0),
+                        b = -t,
+                        r = aspect*t,
+                        l = -r;
+
+                // calculate the object coordinates from their NDC coordinates
+                var z = -world.getViewDistance();
+
+                // unproject to get the position of the origin in GL
+                var x = -z*(r-l)/(2.0*zn)*xNDC,
+                        y = -z*(t-b)/(2.0*zn)*yNDC;
+                z = 0.0;
+
+                // transform by the object's transformation matrix
+                var glPt = MathUtils.transformPoint( [x, y, z], this.getMatrix() );
+
+                return glPt;
+        };
+
     this.buildBuffers = function () {
         // this function must be overridden by the base class
         alert("GLGeomObj.buildBuffers must be overridden by base class");