Mathf.Floor vs. (int) in performance

Question

I'm creating and translating a few algorithms when I'm wondering which is faster?

a) (int)float

or

b) Mathf.FloorToInt(float)

Thanks in advance.

EDIT: If there is a faster way than either of those, that would be helpful too.

Answer 1

Do a test with Stopwatch like I mentioned. This answer is here because I believe that the result in your answer is wrong.

Below is a simple performance test script that uses loop since your algorithm involves many loops:

void Start()
{

    int iterations = 10000000;

    //TEST 1
    Stopwatch stopwatch1 = Stopwatch.StartNew();
    for (int i = 0; i < iterations; i++)
    {
        int test1 = (int)0.5f;
    }
    stopwatch1.Stop();

    //TEST 2
    Stopwatch stopwatch2 = Stopwatch.StartNew();
    for (int i = 0; i < iterations; i++)
    {
        int test2 = Mathf.FloorToInt(0.5f);
    }
    stopwatch2.Stop();

    //SHOW RESULT
    WriteLog(String.Format("(int)float: {0}", stopwatch1.ElapsedMilliseconds));
    WriteLog(String.Format("Mathf.FloorToInt: {0}", stopwatch2.ElapsedMilliseconds));
}

void WriteLog(string log)
{
    UnityEngine.Debug.Log(log);
}

Output:

(int)float: 73

Mathf.FloorToInt: 521

(int)float is clearly faster than Mathf.FloorToInt. For stuff like this, it is really bad to use the FPS from the Editor Stats to make the judgement. You do a test with the Stopwatch. The FPS should be used when writing shader code.