Why does changing the scale of my object break its child's shader?

Question

I have a player game object. Whenever I change direction, I flip the player's x scale, so it's 1 when he's facing right and -1 when he's facing left.

This code is responsible for flipping the player scale and moving the player horizontally:

void FlipScale()
{
    facingRight = !facingRight;
    transform.localScale = new Vector2(transform.localScale.x * -1, transform.localScale.y);
}

void MoveHorizontally()
{
    if (wantsToMoveLeft && wantsToMoveRight) { return; }

    if (wantsToMoveRight)
    {
        rb.velocity = new Vector2(runVelocity, rb.velocity.y);
        if (!facingRight) { FlipScale(); }
    }
    else if (wantsToMoveLeft)
    {
        rb.velocity = new Vector2(-runVelocity, rb.velocity.y);
        if (facingRight) { FlipScale(); }
    }
}

The player object has a child object, which has the main sprite renderer that uses this shader material:

Continuously changing the Fade from 1 to 0 creates an effect of the player dissolving, finally disappearing completely at 0. Here is what it looks like half-way:

However, when I flip the player using the script above, the shader breaks, and the player disappears. Additionally, when I change the Fade value from 1 to exactly less than 0.1, the player suddenly appears to be glowing:

Flipping the sprite again does not fix the issue. Furthermore, flipping the sprite through the inspector does not break the shader, only when I do it through code. I used this tutorial to create this shader: https://www.youtube.com/watch?v=WiDVoj5VQ4c. This is my current shader graph:

I have just started using shaders, so I apologise if the problem is very obvious. I tried a lot of fixes on stack overflow and other websites, but nothing has worked so far. If I didn't include enough information, please ask.

EDIT 1: Found out that, when the shader breaks, the player starts glowing whenever the Fade value is below the Edge value. If it's the same or above, the player looks normal, but the dissolve effect still doesn't work.

EDIT 2: Changing to an unlit shader doesn't fix the issue.

score 1 · Accepted Answer · answered Sep 06 '20 at 12:55

1

So I recently came back to the project and after testing for about an hour, I facepalmed myself really hard when I found out the problem.

I was using Vector2 to flip the scale!!! Vector2 defaults the z value to 0. That's why flipping it in the inspector didn't break anything...

The solution is to simply use Vector3 like so:

transform.localScale = new Vector3(-transform.localScale.x, transform.localScale.y, tranform.localScale.z);

or:

transform.localScale = new Vector3(-transform.localScale.x, transform.localScale.y, 1f);

answered Sep 06 '20 at 12:55

Seminix

97
9

1

I had the same problem. Thank you very much! May I ask why Vector2 would break it while Vector3 doesn't? – Tom Xuan Aug 30 '21 at 05:20
If you set the `localScale` of an object to a Vector2, it will default `localScale`'s Z value to 0. This can cause all sorts of problems including shader bugs. I don't know the exact reason for it though. With a Vector3 you can set the Z value to whatever you want. The first example I gave keeps the original Z value. The second example just sets it to 1. – Seminix Sep 29 '21 at 19:13

Why does changing the scale of my object break its child's shader?

1 Answers1