Blur shader for Godot 4.x?

xyz

CryptoMares it does not blur the environment skybox

It should. Post a screenshot and your scene setup.

CryptoMares

xyz It's a debug panel inside of my character controller:

Also as you can see, the blurred image is misaligned slightly:

xyz

CryptoMares Misalignment likely just a trivial issue of uv transformation. I'm more interested in environment not being affected, although that's not really visible in the screenshots.

Where did you get that shader code?

CryptoMares

xyz On Shadertoy.

This is the result of a few attempts to convert it for Godot 4 with AI. This is the original code:

const int samples = 32,
          LOD = 2,         // gaussian done on MIPmap at scale LOD
          sLOD = 1 << LOD; // tile size = 2^LOD
const float sigma = float(samples) * 0.25;
float gaussian(vec2 i) {
    return exp( -.5* dot(i/=sigma,i) ) / ( 6.28 * sigma*sigma );
}
vec4 blur(sampler2D sp, vec2 U, vec2 scale) {
    vec4 O = vec4(0);  
    int s = samples/sLOD;
    
    for ( int i = 0; i < s*s; i++ ) {
        vec2 d = vec2(i%s, i/s)*float(sLOD) - float(samples)/2.;
        O += gaussian(d) * textureLod( sp, U + scale * d , float(LOD) );
    }
    
    return O / O.a;
}
void mainImage(out vec4 O, vec2 U) {
    O = blur( iChannel0, U/iResolution.xy, 1./iChannelResolution[0].xy );
}

xyz

CryptoMares If this is for backgrounds, you may even not need to do any gaussian averaging. Just sample a small mipmap and let the bilinear filtering do the blur. Might be good enough.

xyz

CryptoMares

shader_type canvas_item; uniform sampler2D t: hint_screen_texture, filter_linear_mipmap;
void fragment(){COLOR.rgb *= textureLod(t, SCREEN_UV, 4.0).rgb;}

CryptoMares

xyz

I'm pretty happy with the blur here:

shader_type canvas_item;

uniform float blur_strength = 1.0; // Blur strength

uniform float blur_amount : hint_range(0.0, 5.0) = 2.0;
uniform sampler2D SCREEN_TEXTURE : hint_screen_texture, filter_linear_mipmap;

// Gaussian weight calculation
float gaussian(vec2 i, float sigma) {
    return exp(-0.5 * dot(i/sigma, i/sigma)) / (6.28318530718 * sigma * sigma);
}

void fragment() {
    vec2 pixel_size = blur_strength / SCREEN_PIXEL_SIZE;
    vec4 blur_color = vec4(0.0);
    float total_weight = 0.0;
    
    // Sample size - adjust for quality vs performance
    const int SAMPLE_COUNT = 15;
    float sigma = blur_amount;
    
    // Perform blur
    for (int x = -SAMPLE_COUNT; x <= SAMPLE_COUNT; x++) {
        for (int y = -SAMPLE_COUNT; y <= SAMPLE_COUNT; y++) {
            vec2 offset = vec2(float(x), float(y)) / pixel_size;
            float weight = gaussian(offset, sigma);
            blur_color += texture(SCREEN_TEXTURE, SCREEN_UV + offset) * weight;
            total_weight += weight;
        }
    }
    
    // Normalize the result
    COLOR = blur_color / total_weight;
}

The only problem now is misalignment:

You said it would be easy to correct?

EDIT: It turns out that the misalignment occurs because of the lens distortion post processing shader I have applied to the whole screen. I wonder if it's possible to make this blur shader to affect the already post-processed frames?

xyz

CryptoMares I'm pretty happy with the blur here:

Why use 3 lines of code when you can use 30 eh? 😃

CryptoMares

xyz It didn't work on my end, unfortunately. Don't know why.

This is the effect of your 3 line shader I'm getting:

xyz

CryptoMares It didn't work
CryptoMares Don't know why

If you want success in making computer programs, you need to cultivate active curiosity and hands-on problem solving skills.
The above statements reflect an attitude that's kinda opposite of that 🙁

xyz

CryptoMares This is the effect of your 3 line shader I'm getting:

How about now?

shader_type canvas_item; uniform sampler2D t: hint_screen_texture, filter_linear_mipmap;
void fragment(){COLOR = vec4(textureLod(t, SCREEN_UV, 4.0).rgb, 1.0);}

CryptoMares

xyz If you want success in making computer programs, you need to cultivate active curiosity and hands-on problem solving skills. The above statements reflect an attitude that's kinda opposite of that 🙁

My brain is small - I'm simply working with what I've got 🤤

How about now?

Yes, this works well:

Thank you!