which texture filter can get the best grayscale image magnify effect

my app overlay some grayscale images(a coverage black & white image) to a texture to simulate light effect,the grayscale images’ size are all 256x256,but the dest texture are all large than it,so I had to magnify the grayscale.I want to know which texture filter or technology can get the best grayscale image magnify effect,I heard the “Hardware Shadow Mapping” extern is the one I want,but I how use it?I just want the best grayscale image magnify effect.


You need GL_LINEAR for your purposes, there’s not a lot of choice, there may be better filters that give better results on rare hardware.

Hardware shadow mapping refers to percentage closer filtering but that involves testing a depth texture against an interpolated texture coordinate and producing a binary value then interpolating the results of multiple such tests (typically 4) it does not give great quality in hardware given the number of samples even if hardware supports multiple tests. Some game developers (including Carmack) are experimenting with multiple such tests in a shader using multiple texture probes). I don’t think this is what you’re looking for.