make show raster better
With NaN's for background and values no longer bound to 0..255 (i.e. We can rely on floating point textures from OpenGL now), let's automatically scale and bias to get something visual.
With NaN's for background and values no longer bound to 0..255 (i.e. We can rely on floating point textures from OpenGL now), let's automatically scale and bias to get something visual.