As a follow up to cover the small details-
The gun sight bitmap probably should be the same size as the main 2D panel bitmap. Because you usually won't know where the VC poly is located a full sized bitmap will catch it somewhere anyway. That is, if in fact the image needs a polygon to match with - I am totally unclear on this part.
The bitmaps used for panels are a regular windows bitmap format BUT it must be 256 colors or less. Pure black RGB 0,0,0 will be translated as clear, so no alpha channel is required.
The gun sight bitmap probably should be the same size as the main 2D panel bitmap. Because you usually won't know where the VC poly is located a full sized bitmap will catch it somewhere anyway. That is, if in fact the image needs a polygon to match with - I am totally unclear on this part.
The bitmaps used for panels are a regular windows bitmap format BUT it must be 256 colors or less. Pure black RGB 0,0,0 will be translated as clear, so no alpha channel is required.