handling large bitmaps in OpenGL ES and Android

Question

I created a map app that uses a very large image as my map. It shows high resolution tiles when the user zooms in to a certain degree and a lower-res bitmap of the whole image when zoomed out past 50%. It works OK, on my origional droid sometimes I can see a very slight lag due to the new tiles being drawn into and from the garbage collector.

Im now thinking about how OpenGL ES would be a better way to render. Ive never touched it before, but from what ive been reading in different turoials, it seems i could create a quad that has 8 faces or so, and enable culling so it only draws the images that are currently visible on the screen.

Would this eliminate the lag completely? In my test app now I have tiles being loaded on app startup but i can tell the lag is due to those tiles being drawn for the first time. Thanks.

Answer 1

I have written an OpenGL-based map view and it's bloody awesome if I say so myself. Sadly it's for a commercial project so I can't offer code. I can however tell you that it has 1 rendering thread, a pool of 8 tile downloading threads, and (most pertinent to your question) 1 storage thread that loads and saves tiles to the NAND flash or the SD card. Rendering is done one tile at a time, each tile being 2 triangles (there are no quads in ES). It's still blisteringly quick.