Feature Level 9.1 texture question

Question

This doc only said, Feature Level 9.1

 - Max Texture Dimension:  2048

 - Nonpowers-of-2: Yes

Are non-square and  Nonpowers-of-2 textures will be extend to square and powers-of-2 texture inside graphic card , so that the memory is not saved?

So is it a bad idea to create a long and narrow texture?

Answer 1

The chart actually reads for FL 9.1 "Nonpowers-of-2 conditionally(3)" as "Yes"; Nonpowers-of-2 unconditionally" is "No"

Footnote 3 says:

At feature levels 9_1, 9_2 and 9_3, the display device supports the use of 2-D textures with dimensions that are not powers of two under two conditions. First, only one MIP-map level for each texture can be created, and second, no wrap sampler modes for textures are allowed (that is, the AddressU, AddressV, and AddressW members of D3D11_SAMPLER_DESC cannot be set to D3D11_TEXTURE_ADDRESS_WRAP).

Basically you are free to use non-power-of-2 textures to save memory, but you can only render them on FL 9.1 without mipmapping and using only wrap modes other than "WRAP". As such, they are probably fine to use if you are rendering '1:1' pixel textures such as UI, but they are not good choices for textures on 3D objects since mipmapping is essentially to quality filtering and texture performance.