Advanced virtual texture topics

A virtual texture is a mip-mapped texture used as cache to allow a much higher resolution texture to be emulated for real-time rendering, while only partly residing in texture memory. This functionality is already accessible with the efficient pixel shader capabilities available on the recent generations of commodity GPUs. In this chapter we will be discussing technical implications on engine design due to virtual textures use, content creation issues, results, performance and image quality. We will also cover several practical examples to highlight the challenges and to offer solutions. These include texture filtering, block compression, float precision, disk streaming, UV borders, mip-map generation, LOD selection and more.