Making image white

[Gunroar:Cannon()]

Is there any easy way without shaders to make an image completely white? Like how to make an image be black the color can be set to (0,0,0).

[EngineerSmith]

Replace the area it's being drawn with a rectangle that's white, is the best way I can think of if you don't want to use a shader. Otherwise you could look into blend modes, but none of them can do that off the top of my head.

[MrFariator]

Another approach I suppose would be to use stencils, but ultimately using shaders would be the better option.

[grump]

without shaders

*sigh*

You can make the pixels in an ImageData white and preserve the alpha channel:

Code: Select all

local imgd = love.image.newImageData('theimage.png')
imgd:mapPixel(function(x, y, r, g, b, a)
	return 1, 1, 1, a
end)
local whiteImage = love.graphics.newImage(imgd)

[Gunroar:Cannon()]

Replace the area it's being drawn with a rectangle that's white

Won't that just draw a white rectangle?

Okay, for the sake of comparison how would one go about it with shaders?

[grump]

Won't that just draw a white rectangle?

To be fair, "How to make an image white" is not a very clear question and open to interpretation. An example image would have been helpful. An image without alpha channel would become a white rectangle, so it's a valid suggestion.

Okay, for the sake of comparison how would one go about it with shaders?

Code: Select all

vec4 effect(vec4 color, Image img, vec2 tc, vec2 fc) {
	return vec4(color.rgb, color.a * Texel(img, tc).a);
}

That's for any color and alpha set with love.graphics.setColor, not just white.

[Gunroar:Cannon()]

Code: Select all

vec4 effect(vec4 color, Image img, vec2 tc, vec2 fc) {
	return vec4(color.rgb, color.a * Texel(img, tc).a);
}

That's for any color and alpha set with love.graphics.setColor, not just white.

Nice, it worked out
I was scwared it won't work with all OSs
Just 2 notes (I observed, not facts):
1) It doesn't work with love.graphics.setBlendMode("alpha", "premultiplied") (Giant white block)
2) Doesn't work with setColor, though I fixed it by changing it

Code: Select all

return vec4(1,1,1,color.a * Texel(img, tc).a);

Yay, *shaida*

All in all, it works! Thank you all.
Oh, and I was trying to do a flashing white effect for damage taking

#gamejuice #gamefeel

[grump]

I was scwared it won't work with all OSs

That's unreasonable. There's always shaders running. If you don't use a custom one then a default shader is used that does pretty much the same calculations as this one, just in a slightly different way. This is a pretty basic thing that'll run on a potato.

1) It doesn't work with love.graphics.setBlendMode("alpha", "premultiplied") (Giant white block)

In that case the shader should return premultiplied colors.

Code: Select all

vec4 effect(vec4 color, Image img, vec2 tc, vec2 fc) {
  float a = color.a * Texel(img, tc).a;
  return vec4(color.rgb * a, a);
}

Are you sure you have an Image that is premultiplied? Or is it a Canvas?

2) Doesn't work with setColor

I don't believe you. You did it wrong.

[Gunroar:Cannon()]

To make it clear, what I mean by doesn't work with setColor is that setColor makes the image not white? Is this still wrong? I honestly don't know. I'll check it later...

Edit: Oh, yes. I use premultiplied on an image. Any bad side effects? Any other simple but cool (and maybe more useless) shader tricks? E.g. rainbow? (I dunno, just thought of that off top of head)

[grump]

To make it clear, what I mean by doesn't work with setColor is that setColor makes the image not white?

The shader + setColor makes all pixels that color. No reason why it shouldn't. Hardcoded white is the same as setColor(1, 1, 1).

Edit: Oh, yes. I use premultiplied on an image. Any bad side effects?

Yeah, blending will give wrong results unless the Image has premultiplied alpha, which is unlikely. If it looks okay with your images then go for it.