Items don't have ResourceLocations. They have a IIcon object which holds the UV-coordinates of the texture on a giant image of which the ResourceLocation is located at
TextureMap.locationItemsTexture
. If you want to use this in a GUI, you have to get the IIcon of the Item first, bind the
TextureMap.locationItemsTexture
, and then call the
drawTexturedModelRectFromIcon(x,y,IIcon,width,height)
to draw the IIcon of the item.