CODEWITHSUNDEEP
c#unity-game-engine
Gleb Markovski
Gleb Markovski

Reputation: 1

Cant convert double to float c#, even thought using cast and no doubles in equasion. Unity

Ok so I was searching the internet for the answer and couldnt find it. I am extremely new, started 4 days ago.

I have some code to make the player rotate to where they moving, like in flappy bird, you know.

using UnityEngine;
using System;

public class PlayerAngle : MonoBehaviour
{
    public Rigidbody rb;

    // Update is called once per frame
    void Update()
    {

        float x = transform.rotation.x;
        float y = transform.rotation.y;
        float xvel = (float)rb.velocity.x;
        float yvel = (float)rb.velocity.y;

        x = Math.Sin(yvel);
        y = Math.Sin(xvel);

        transform.Rotate(x, y, 0);
    }
}

It doesn't want to accept xvel and yvel which are supposed to be floats in Math.Sin.

Here is the exact error it gives me:

Error CS0266 Cannot implicitly convert type 'double' to 'float'. An explicit conversion exists (are you missing a cast?)

Please help me, I have spent hours trying to figure this out.

Thank you.

Upvotes: 0

Views: 1468

Answers (4)

Milan Egon Votrubec
Milan Egon Votrubec

Reputation: 4049

This is a Unity related question, so we can assume that you were trying to use the Mathf static class. The System.Math class uses double by default.

Your code actually has a lot of extraneous operations. For example, you don't need to read the transform.rotation values.

With all that in mind, your updated code would look like:

void Update()
{
    var x = Mathf.Sin(rb.velocity.y);
    var y = Mathf.Sin(rb.velocity.x);
    transform.Rotate(x, y, 0);
}

Upvotes: 0

Rufus L
Rufus L

Reputation: 37020

The error is telling you there is no implicit conversion from a double to a float.

The reason for this is that the double type is a 64-bit (double-precision) number, and the float type is only a 32-bit (single precision) number, so there is the potential for a loss of precision when converting from double to float, and the authors didn't want that loss to happen "accidentally" during an assignment.

However, you can always explicitly cast the values to the correct type:

x = (float) Math.Sin(yvel);
y = (float) Math.Sin(xvel);

Or, better yet, just use double types all the way through:

void Update()
{
    double xVel = rb.velocity.x;
    double yVel = rb.velocity.y;

    double x = Math.Sin(yVel);
    double y = Math.Sin(xVel);

    transform.Rotate(x, y, 0);
}

Or, more precicely:

void Update()
{
    transform.Rotate(Math.Sin(rb.velocity.y), Math.Sin(rb.velocity.x), 0);
}

Upvotes: 0

Guru Stron
Guru Stron

Reputation: 142038

One of the options is casting result of Math.Sin to float:

    x = (float)Math.Sin(yvel);
    y = (float)Math.Sin(xvel);

.NET Math.Sin accepts and returns double, implicit conversion from float to dobule exists but in reverse you need to use explicit cast.

Upvotes: 2

Efraim Newman
Efraim Newman

Reputation: 1041

You can also use unity's Mathf.Sin() which returns a float

Upvotes: 1

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