Not detecting a simple collision?

Questions & Answers
1

Hey, folks! I might be crazy, but…for me, the first print statement will print “Normal was: (0,1,0)”, but the second print statement then prints nothing. What am I doing wrong, here? I’m not really sure what the heck is up. Why would it print that statement, but then not respond to the conditional?

function OnCollisionEnter(collision: Collision)
    {
    	for (var contact : ContactPoint in collision.contacts) 
    	{	
    		print("Normal was:" + contact.normal);
    		if(contact.normal == Vector3(0.0, 1.0, 0.0))
    		{
    			print("Detected collision!");
    	        }
    	}
    		
    }
3

It’s a float issue. The normal is a computed value, so is probably something like (0, 0.999999, 0.00001). The inspector only shows 1 decimal. You can print contact.normal.x*100000 to see more. But, even regular prints often “round to the nearest” on the screen.

The official computery way is to check: if(Mathf.Approximately(contact.normal.x, 0) && Mathf.Approximately(contact.normal.y, 1) ...)

An example of float rounding: 1/3 is 0.3333 with 3’s forever. The computer can only store about seven of them. So (1/3)*3 is 0.9999999. Additionally, the computer uses binary, so really stores the 1/2’s place, the 1/4ths place, the 1/8ths place … . One fifth is the non-repeating decimal 0.2 for us, but 1/5th in binary is 1/8 + 1/16 + 1/128 … and repeats, so has to be rounded to the nearest.

2

Check if that damned Collapse button in the Console pane isn’t pressed: if you click this SOB button by mistake, the Console doesn’t show repeated lines, driving us crazy.