Question about Linear Filtering

[Danyal Zia]

So, I was wondering is Linear Filtering in PPSSPP same as GL_LINEAR mode instead of GL_NEAREST? If enabling Linear Filtering changes it to GL_LINEAR then how devs were able to do texture mapping using it without experiencing usual black borders around moving textures/objects? Do real PSP have texture filtering mode (Linear Filtering) unlike Nintendo DS? I could see it in source of github of PPSSPP but I can't understand the procedure of github, too bad!