How can I create Raycast bullet innaccuracy as a cone?

Questions & Answers
1

The earliest solutions I had come up with for having deviation from perfect accuracy involved varying the direction up and down as well as left and right by a random number. While this worked (and it was on a much earlier project that I no longer have), it produced a square pattern. While I have figured out how to make the possible area a cone, I now cannot figure out how to get it to point in the appropriate direction.

	float absDir = Random.value * Mathf.PI * 2;
	float offShoot = Random.value * accuracy;
	Vector3 Dir = new Vector3(Mathf.Cos(absDir) * offShoot,Mathf.Sin(absDir) * offShoot, 100);
	Dir.Normalize();
	RaycastHit wasShot;
	if (Physics.Raycast(Muzzle.position, Dir, out wasShot, 1000.0f))
	//Etc

I can’t multiply it by another Vector3, such as Muzzle.forward, and none of the Vector3 class functions look like they’d be of much use, either.

2

I extracted this from my scripts, it might not be what you want or work with your project, but I am sure it will help you in one way or another.

using UnityEngine;
using System.Collections;

public class Shotgun : MonoBehaviour {
	
	//These 2 controls the spread of the cone
	public float scaleLimit = 2.0f;	
	public float z = 10f;
	
	//Shoots multiple rays to check the programming
	public int count = 30;
	
	void Update () {
		for( int i = 0; i < count; ++i ) {
			ShootRay();	
		}
	}
	
	void ShootRay() {
		//  Try this one first, before using the second one
		//  The Ray-hits will form a ring
		float randomRadius = scaleLimit;     		
		//  The Ray-hits will be in a circular area
		float randomRadius = Random.Range( 0, scaleLimit );		
		
		float randomAngle = Random.Range ( 0, 2 * Mathf.PI );
		
		//Calculating the raycast direction
		Vector3 direction = new Vector3(
			randomRadius * Mathf.Cos( randomAngle ),
			randomRadius * Mathf.Sin( randomAngle ),
			z
		);
		
		//Make the direction match the transform
		//It is like converting the Vector3.forward to transform.forward
		direction = transform.TransformDirection( direction.normalized );
		
		//Raycast and debug
		Ray r = new Ray( transform.position, direction );
		RaycastHit hit;		
		if( Physics.Raycast( r, out hit ) ) {
			Debug.DrawLine( transform.position, hit.point );	
		}	
	}
}
3

This seems like a geometry problem where the center axis of the cone is where the player fires, i.e. the cross hairs, then you apply a random rotation to point that offset that direction. So, I would first tilt the center axis between zero and your max cone angle along a single axis perpendicular to the center. Then I would spin the result between zero and 360 degrees along the original center axis. So,

Quaternion GetRandomInsideCone(float conicAngle) {
	// random tilt right (which is a random angle around the up axis)
	Quaternion randomTilt = Quaternion.AngleAxis(Random.Range(0f, conicAngle), Vector3.up);
	
	// random spin around the forward axis
	Quaternion randomSpin = Quaternion.AngleAxis(Random.Range(0f, 360f), Vector3.forward);
	
	// tilt then spin
	return (randomSpin * randomTilt);
}

you can then do

	// fire in direction with random 10 degree offset
	Vector3 fireInDirection = new Vector3(3, 4, 5);
	Vector3 fireInRandomDirection = GetRandomInsideCone(10) * fireInDirection;
	
	// or rotate an object within the cone
	Transform weapon = GetSomeTransform();
	weapon.rotation = GetRandomInsideCone(conicAngle) * originalRotation;