Cannot detect input in void OnCollisionEnter()

Question

Code:

void OnCollisionEnter()
{
    if (Input.GetMouseButton(0))
       {
            // do something
       }
}

Of course, this code does not work. What I intend to do: "After collision, if the user is pressing down, do something". How can we write this another way? I can't figure it out.

Answer 1

Do something like this:

var timeSinceCollision = 999;

void Update() {
    timeSinceCollision += Time.deltaTime;
    if(timeSinceCollision < 0.5 && Input.GetMouseButtonDown(0)) {
        // do something
    }
}

void OnCollisionEnter() {
    timeSinceCollision = 0;
}

The 0.5 makes it so that there's a bit of allowable tolerance for when the player collides with whatever and them being able to perform the action (no one is going to be able to press the button the same frame the collision occurs on: ideally that would be 1/60th of a second!).

Edit: Also use GetMouseButtonDown, which will only be true on the frame that the button is first pressed and false thereafter. It prevents the player from holding down the button, then bumping into something, and getting the effect despite doing things out of order.

Answer 2

I think you scenario is to stand over a special block then do something or open up the door from side panel. In block type case OnCollision is OK but in door type case I'd recommend OnTrigger, well according to your code, use OnCollisionStay instead of OnCollisionEnter

void OnCollisionStay(Collision col)
{
    if (Input.GetMouseButton(0))
       {
            // do something
       }
}