Platforming and slopes

[DustyPorViva]

Anyone have any suggestions on how to accomplish this? I've tried checking for slope tiles ahead of movement, and incrementing the player.y accordingly(if a 45 degree angle, increment player.y the same as speed, if a 22.5 degree angle, half the speed)... but that's proved unreliable, especially at speeds not divisible by .25. Not only that, but it's not a solid detection(for instance, if the player falls on a slope, nothing would happen).

Right now I'm using NPC's and simply using testnpc(since an NPC inherits the shape of the image) to 'stick' the player onto the slope of the NPC in pixel precision, but this is also proving unreliable at higher speeds.