Raycasting to avoid falling (FPS game)

I’m trying to make it so that the player won’t be able to walk into a place where he would fall. Meaning I want to do a raycast into the direction in which the player is moving (which isn’t necessarily forward as the player might for example strafe) and if there is a fall of more than 1 unit (no need to be this precise), prevent movement to that direction.

Due to the sheer amount of level geometry, I cannot use colliders for this. Any help would be appreciated (preferably in C#).

I searched for a similar solution and I found this thread: “Raycast to check for potential pitfalls” (http://forum.unity3d.com/threads/138406-Raycast-to-check-for-potential-pitfalls), but I seem to be unable to modify it to suit my needs.

Acknowledgement: As a basis for this script I am using “FPSWalkerEnhanced” (unifycommunity.com) by Eric Haines (Eric5h5).

A side note: I copied (or at least tried to copy) only the relevant parts from the script to this post, since the script itself is exceedingly long (with a lot of actions which have nothing to do with player movement). So if it seems there is an obvious omission, that’s probably the reason.

void Update() {

	// Get axis
float inputX = Input.GetAxis("Horizontal");
float inputY = Input.GetAxis("Vertical");

	// Prevent sidestepping speed increase
float inputModifyFactor = (inputX != 0.0f && inputY != 0.0f)? .7071f : 1.0f;

// Determine if player is moving
if(oldPos.x != transform.position.x || oldPos.z != transform.position.z) {
	isMoving = true;
}
else {
	isMoving = false;
}
oldPos = transform.position;

// If player is touching the ground		
if (grounded) {
	// If player was falling
	if (falling) {
		falling = false;

		// Give damage if fallen for too much
		if (myTransform.position.y < fallStartLevel - fallingDamageThreshold) {
			FallingDamageAlert (fallStartLevel - myTransform.position.y);	
		}
	}

	// Movement direction
	moveDirection = new Vector3(inputX * inputModifyFactor, -antiBumpFactor, inputY * inputModifyFactor);
	moveDirection = new Vector3(inputX, -antiBumpFactor, inputY);
	moveDirection = myTransform.TransformDirection(moveDirection) * speed;


		// Jumping
		if (Input.GetButtonDown("Jump")) {
			Jump();
		}
}
else {
	// If player was not falling
	if (!falling) {	
		falling = true;

		// Determine start position of fall
		fallStartLevel = myTransform.position.y;
	}

	// If airControl is allowed, allow movement while on air
	if (airControl) {
		moveDirection.x = inputX * speed * inputModifyFactor;
		moveDirection.z = inputY * speed * inputModifyFactor;
		moveDirection = myTransform.TransformDirection(moveDirection);
	}
}


// Apply gravity
moveDirection.y -= gravity * Time.deltaTime;

// Move the player
grounded = (controller.Move(moveDirection * Time.deltaTime) & CollisionFlags.Below) != 0;
}

Why don’t you just add some colliders in an empty game object and position them in the places where the player won’t be able to walk?

I guess is a pretty quick solution and will not require Raycast, which isn’t the most light thing for the CPU.

Just set your ray start point to player.position + player.GetPlanarVelocity() * (an amount of time).

Or you can make it a constant buffer distance from ‘pits’ by using player.position + player.GetPlanarVelocity.normalized() * (a distance).

Looks like your ‘moveDirection’ would work as velocity -

function GetPlanarVelocity() : Vector3 { return new Vector3(moveDirection.x, 0, moveDirection.z); }

Shoot your ray straight down from that point. If it can travel farther than [1 meter] then it’s a ‘pit’.

If you can ‘hover’ above safe ground, you might need to raycast straight down from player to find the floor, then nudge over like above, then raycast straight down from the new point.