Shader returns only white

[crocs]

Hi there!
I've seen some other posts that cover a similar topic to this, but none of them explain to me how to correct the issue.

Code: Select all

local pixelShader = love.graphics.newShader[[
    extern vec2 resolution;

    vec4 effect( vec4 color, Image texture, vec2 texture_coords, vec2 screen_coords ) {
        vec2 largePosition = floor(texture_coords / resolution) * resolution;

        vec4 resultant = Texel(texture, largePosition);

        
        
        return resultant;
    }
]]

The code above is supposed to pixelate the visuals. Resolution is a vector 2 that changes how many pixels it makes.

I see online that you return resultant * colour, but because resultant is always white it will always just return the original colour. Resultant itself is always 1,1,1,1. Can my shader not check the colour on love.draw (using graphics.setcolor)? If not, how can I colour my program so the shader can change it?

Thank you!!

[zorg]

Hi and welcome to the forums!

It's late and i might be wrong, but this is how i see it:

The resolution variable storing how many pixels you want to simulate in width and height is not how that works;
if resolution is {1,1}, then you'll get width x height pixels,
if resolution is {2,2}, then you'll get (width/2) x (height/2) pixels,
and so on.

I'm guessing you're passing in such a large pair of numbers to resolution, that you're basically only sampling one pixel, which happens to be fully white.

You could potentially fix this by passing in {actualwidthinpixels/wantedwidthinpixels, actualheightinpixels/wantedheightinpixels} instead.

[pgimeno]

This will only work correctly if resolution.x is 1/width and resolution.y is 1/height.

Maybe you want the opposite: vec2 largePosition = floor(texture_coords * resolution) / resolution;

[crocs]

Hi and welcome to the forums!

It's late and i might be wrong, but this is how i see it:

The resolution variable storing how many pixels you want to simulate in width and height is not how that works;
if resolution is {1,1}, then you'll get width x height pixels,
if resolution is {2,2}, then you'll get (width/2) x (height/2) pixels,
and so on.

I'm guessing you're passing in such a large pair of numbers to resolution, that you're basically only sampling one pixel, which happens to be fully white.

You could potentially fix this by passing in {actualwidthinpixels/wantedwidthinpixels, actualheightinpixels/wantedheightinpixels} instead.

Hello!
By instead returning the colour of the position (not the colour of the pixel), you can see where each pixel is supposed to go (and it looks pretty cool aswell ).

Code: Select all

local pixelShader = love.graphics.newShader[[
    extern vec2 resolution;

    vec4 effect( vec4 color, Image texture, vec2 texture_coords, vec2 screen_coords ) {
        vec2 largePosition = floor(screen_coords / resolution) * resolution;

        vec4 resultant = Texel(texture, largePosition);

        
        
        return vec4 (largePosition / love_ScreenSize.xy,1,1   );
    }
]]

The higher the vec2 resolution is, the larger the pixels (not the other way that I thought would be amount of pixels onscreen, thank you!!). Knowing this, I can see exactly what pixel that I should be copying for each square (the upper left corner of each square), but still the Texel() function will always return white. Am I using the wrong function to get the colour of a pixel on screen?
Thank you for the help so far!

[Andlac028]

If you want to make whole game look pixelated, you can just draw everything to smaller canvas than window and then upscale the canvas with nearest filter (with love.graphics.setDefaultFilter or set filter just to canvas) and draw it to full window

[ReFreezed]

Note that Texel() expects normalized coordinates which texture_coords is, but screen_coords is in pixels. If resolution is in pixels then both floor(texture_coords/resolution) and floor(screen_coords/resolution) will round to 0 most of the time, so you're sampling the same pixel.