Is it possible to fill transparency with white in a texture in code ?

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I have some textures containing some transparency parts (a donut, for example, which would show a transparent center). What I want to do is fill the middle of the donut (or anything else) with a plain white, in code (I don't want to have a double of all my assets that need this tweak in one part of my game).

Is there a way to do this ? Or do I really have to have 2 of each of my assets ?

Thanks for the help !

Answer 1

Answer by Owen-Reynolds · Jun 04, 2014 at 08:46 PM

Yes, this is simple (assuming you know loops and color formats.) Texture2D should have all the info you need (getPixels, setPixels... ) to read the old texture, and create/write/save the new. Reading alpha is no different than reading RGB.

Probably use: Color c2=Color.Lerp(c1, Color.White, c1.alpha); c2.a=1; to get the white to fade in with the alpha.

Or, if you just happen to have alpha==white in the original image, simply use a non-transparent shader (with the original image.) It will show all the RGB, ignoring the alpha.

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Bypp · Jun 04, 2014 at 09:48 PM 0

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But this will make all of my alpha become white right ? I want only the middle of said donut to be white ! This will make the whole "square" of my texture white, which is something I don't want. Am I missing something else here ?

tanoshimi · Jun 04, 2014 at 10:22 PM 0

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No, it will make the transparent parts to white, and leave the nontransparent pixels as they were. Isn't that what you wanted?

Owen-Reynolds · Jun 05, 2014 at 12:18 AM 1

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Well, sure, if the inside and edges are transparent, this would change all. A cheap "center only" is to hand-do math to say "if within a radius of the center." Can use (x-halfPixelWd)/pixelWd to get a -0.5 to 0.5 for how far a pixel on x is from the center. Can probably also look up how to make a circle texture, and s$$anonymous$$l that.

tn7111 · Sep 03, 2021 at 01:56 PM 0

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Umm, I'd say rather something like that:

 Color c2 = Color.Lerp(Color.White, c1, c1.alpha/255f);
 c2.a=255;

then you get an image as if you put png onto totally white background layer in Photoshop or similar soft.

Owen-Reynolds tn7111 · Sep 03, 2021 at 03:12 PM 1

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No need to divide by 255. Colors in Unity are scaled into range 0-1. Color.white is (1,1,1,1), ca.alpha is 1 (for a solid image), and so on.

Answer 2

Answer by Nerevar · Jun 04, 2014 at 04:06 PM

Hello,

I think you would need to write an editor script for that.

using a custom TextureImporter

Then you may be able to access variables you need

alt text

if you can set AlphaFromGrayscale and AlpaIsTransparency booleans (which I did no test) problem would be solved.

regards

alpha.png (15.0 kB)

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Bypp · Jun 04, 2014 at 04:58 PM 0

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Thing is, I need to do this on the fly (in code), not change the texture or import settings !

Nerevar · Jun 05, 2014 at 08:27 AM 0

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Yes well you can do it with Texture importer on an editor script

Answer 3

Answer by Jeff-Kesselman · Jun 04, 2014 at 09:10 PM

Another way to do it is to create an all white RenderTexture of the same size and then use http://docs.unity3d.com/ScriptReference/Graphics.Blit.html to copy your original ontop of it.

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Bypp · Jun 04, 2014 at 09:49 PM 0

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I only want to fill the middle part of my texture, not the entire thing !

Is it possible to fill transparency with white in a texture in code ?

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