OpenGL ES Smooth Zooming of Tiled Maps on Raspberry Pi and a Pixel Qi display

A short demonstration of zooming and scale switching when rendering tiled maps (like Google Maps) using OpenGL ES 2 on an older Raspberry Pi B. I'm using a Pixel Qi sunlight readable display, and also show how it switches to sunlight readable reflective grayscale when the backlight is turned off. For more information on the PiChart project, see https://hackaday.io/project/9471-Pi-chart I plan to post the source code.