For the player movement, I just used Godot's move_and_slide() function. All I have to do is to make sure the slope angle is within the accepted interval for the player to slide. If u are not using godot, then I am not quite sure, sorry!
hmm, when i try to implement quake movement, when i try and surf on a slope, my character just falls off and doesn't stick to the surface. Thanks for the tip btw
edit: I just managed to figure it out. Thank you so much for uploading your code, after going through it a few times i manage to figure it out. Again, thank you for uploading this :)))))