Color.Lerp not lerping

Questions & Answers
1

I’m trying to lerp the alpha channel of a sprite renderer but it isn’t lerping, it just changes the alpha value so it instantly disappears instead of fading, I’ve searched everywhere but I can’t find a solution, here’s my code, please help.

(c#)

using UnityEngine;
using System.Collections;

public class MagicWalk : MonoBehaviour
{
	Color fullAlpha = new Color (1f, 1f, 1f, 1f);
	Color emptyAlpha = new Color (1f, 1f, 1f, -1f);
	float speed;
	SpriteRenderer magicCircle;
	ParticleSystem magicPar;
	
	void Awake ()
	{
		magicCircle = GetComponent<SpriteRenderer> ();
		magicPar = GetComponentInChildren<ParticleSystem> ();
	}
	
	void Update ()
	{
		float h = Input.GetAxis("Horizontal");
		speed = Mathf.Abs(h);
		
		if (speed <= 0)
		{
			magicCircle.color = Color.Lerp (fullAlpha, emptyAlpha, 0.5f);
			magicPar.enableEmission = false;
		}
		else if (speed > 0)
		{
			magicCircle.color = fullAlpha;
			magicPar.enableEmission = true;
		}
	}
}
3

Lerp basically is that you have 2 values, Value A and value B. In the third parameter you specify the time. This value should be a value between 0 and 1.

A timeValue of 0 means value A will be reurned. A timeValue of 1 means value B will be returned. A timeValue of 0.5 means a value halfway in between value A and B is returned.

So in your current setup, sinse fullAlpha and emptyAlpha are constant, you will always return the same value (A value between [1,1,1,1] and [1,1,1,-1]).

There are 2 ways of making this work.

1:

float smooth = 1f; // Increase this for higher speed
magicCircle.color = Color.Lerp(magicCircle.color, emptyAlpha, Time.deltaTime * smooth);

Also, see this tutorial, stating at 4:20 for the Color.

2:

private float currentValue = 0f;

void Update ()
{
    float h = Input.GetAxis("Horizontal");
    speed = Mathf.Abs(h);

    if (speed <= 0)
    {
        currentValue = Mathf.Clamp01(currentValue - Time.deltaTime);
        magicPar.enableEmission = false;
    }
    else if (speed > 0)
    {
        currentValue = 1f;
        magicPar.enableEmission = true;
    }
    magicCircle.color = Color.Lerp(fullAlpha, emptyAlpha, currentValue);
}

You’ll notice that the second method’s speed stays constant, while the first method slows down at the end.

On a sidenote, Color values are values between 0 and 1. So setting alpha to -1 is normally somethig you don’t want to do.

2

R,G,B, and A color components range from 0 to 1. So:

Color emptyAlpha = new Color (1f, 1f, 1f, -1f);

should be:

Color emptyAlpha = new Color (1f, 1f, 1f, 0);

Your second problem is a logic problem (well, depends on what you’re trying to do). Your current code says, “if the speed is less than or equal to zero, pick a colour that’s halfway inbetween fullAlpha and emptyAlpha” - is that really what you meant? There’s no “fading” as such.