Making Sprites Flash in a 2D Game...

Unity Engine
1

I was wanting to make my sprites flash in a 2D game when a character takes damage. A long time ago, I made an XNA game in which I created an alternate white sprite for the player’s sprite (programatically I think) then blended this with the original player sprite so as to make it look “whiter”.

I was asking about how to do this programatically in Unity, though someone suggested I might try setting the color attribute of a shader instead. The standard shader seems to assume a lighting system is present, and the other shaders I tried either don’t support tiling or don’t allow the color to be set. Is there an existing shader that will blend a white color into my sprites without lighting?

Someone also suggested just coding this in a new GLSL shader. I could go ahead and do this if it is preferable, though can it be layered on top of a 2D lighting system (separate shader) if I do add one later?

2

Why don’t u just change the Sprite Renderers color for a like half a second when hit then change it back to white?

So like u for example if you wanted to make it flash red then you could make a bool called “hit” and set “hit” to be true when hit then do somethin like -

if (hit == true) {
            GetComponent<SpriteRenderer> ().color = Color.red;
            StartCoroutine(whitecolor());
        }

Then u can like make a Coroutine like this -

IEnumerator whitecolor() {
        yield return new WaitForSeconds(0.5);
        GetComponent<SpriteRenderer> ().color = Color.white;
        hit = false;
    }

So your player would flash red then go back to normal and it wont make the entire sprite red itll just like make it like tinted red i think thats easier then making a GLSL shader to do it lol

1 Like
3

@datahead8888 or u could instantiate a white light that only affects your sprite over the player when hit but i think i like the other way i said above this

4

The sprite renderer already has a color of white by default, which causes the sprites to show up normally. I can only change it to other colors, which are really “darker” than white. This is the sort of thing that led a couple people to suggest writing a shader (Unity actually uses a language other than GLSL it turns out, though you can embed GLSL).

I just checked in BatMan on the NES, though, and the characters don’t appear to flash using a white sprite - it was either orange or yellow. I probably should try both of these colors a bit first, since they can easily be done using the sort of technique you outlined above.

5

You can use a shader, there’s a brilliant Unity Answer here with an example: Shader to flash a 2d sprite to white? - Questions & Answers - Unity Discussions

You create a new material with that shader and apply it to your sprites, either on the Editor or programmatically.

Here’s a simple co-routine to switch the flashAmount on the material:

public IEnumerator Flash()
    {
        while(isInvulnerable) {
  
            if(MathHelper.IsTimeEven())
            {
                GetComponent<Renderer>().material.SetFloat("_FlashAmount",0.8f);
            }
            else
            {
                GetComponent<Renderer>().material.SetFloat("_FlashAmount",0);
            }
      
            yield return null;
        }
    }
6

I may add a 2D lighting system later, which would certainly require a shader. If I decide to use a shader in order to allow sprites to be “whitified”, is it advisable to try to get the two different shaders to run in sequence? I understand it is possible by using multiple passes, though some people have recommended combining them for performance. This, however, is not at all modular, especially if I borrow code for the 2D lighting system. My game in only 2D, anyways.

7

in that case just swap the material when you want the sprite to flash, and swap it back after.

    Material originalMaterial;
    bool flashing;
    public Material flashMaterial;

    void Start () {
        if (GetComponent<SpriteRenderer>().material != null)
            originalMaterial = GetComponent<SpriteRenderer>().material;
    }

    public void FlashWrapper() {
        if (!flashing)
            StartCoroutine("Flash");
    }

    IEnumerator Flash() {
    
        flashing = true;
        GetComponent<SpriteRenderer>().material = flashMaterial;
        yield
        return new WaitForSeconds(1f);
        GetComponent<SpriteRenderer>().material = originalMaterial;
        yield
        return new WaitForSeconds(1f);
        flashing = false;
    }

You’d want to load the material from resources if adding classes dynamically.