added getSize to the bufferobject

include/ACGL/OpenGL/Objects/Buffer.hh

@@ -58,6 +58,15 @@ public:
         glDeleteBuffers(1, &mObjectName);
     }
     GLuint mObjectName;
+
+    //! has the side effect of binding this buffer.
+    //! returned value is in bytes
+    GLsizei getSize( GLenum _asTarget ) {
+        glBindBuffer( _asTarget, mObjectName );
+        GLint value;
+        glGetBufferParameteriv( _asTarget, GL_BUFFER_SIZE, &value );
+        return value;
+    }
 };
 typedef ptr::shared_ptr<BufferObject> SharedBufferObject;
 
@@ -94,10 +103,11 @@ public:
      * In this case no GL wrapper calls should ever get called until one gets set!
      */
     Buffer( SharedBufferObject _pBuffer, GLenum _target )
-        : mSize(0),
-		  mBuffer( _pBuffer ),
+        : mBuffer( _pBuffer ),
 		  mTarget(_target)
-    {}
+    {
+        mSize = mBuffer->getSize( _target );
+    }
 
     virtual ~Buffer(){}
 
@@ -114,7 +124,7 @@ public:
     // ==================================================================================================== \/
 
     //! the GL buffer can get changed at any time
-    void setBufferObject( SharedBufferObject _pBuffer ) { mBuffer = _pBuffer; }
+    void setBufferObject( SharedBufferObject _pBuffer ) { mBuffer = _pBuffer; mSize = mBuffer->getSize( mTarget ); }
 
     // ===================================================================================================== \/
     // ============================================================================================ WRAPPERS \/