Super Mario 64 slide mechanics

Does anybody know how to make a slide like in Super Mario 64:

The charater shoud not be able to go upwards but only sliding downwards.

it’s fairly simple.
You definitely need to change movement mode to a custom one or nothing.
Then you apply impulse based on the slope normal that the capsule component returns from it’s line trace.

Maybe you scale a base speed times that normal to increase or decrease your speed dependent on the slope.
Maybe you set up the W and S buttons to offset the base speed that you apply.

Either way you are relying more on physics then you are on input.

Did not work.

I did … and this was the result …

Does these mechanics work with a triggerbox? Any images would be helpful.

Hello?