径向模糊

对x方向周围像素进行权重混合

shader_type canvas_item;

uniform int SAMPLES = 6;
uniform float WIDTH = 4.0;
uniform vec4 OUTLINE_COLOR = vec4(0.,0.,0.,1.);

uniform vec2 TEXTURE_SCALE = vec2(0.94);

float scurve(float x){
    x = x*2. - 1.;
    return -x*abs(x)*.5+x+.5;
}

vec4 gaussian_blur_h(sampler2D src, vec2 size, vec2 uv, float radius){
    if(radius>=1.0){
        vec4 c = vec4(0.);
//      float width = 1./size.x;
        float divsor = 0.;
        float weight = 0.;
        float radius_multiplier = 1./radius;
        
        for(float x=-10.; x<=10.;x++){
            weight = smoothstep(-1.,1.,1.-abs(x)*radius_multiplier);
            c+=texture(src, uv+vec2(x*size.x,0.))*weight;
            divsor+=weight;
        }
        return vec4(c.r/divsor, c.g/divsor, c.b/divsor, 1.0);
    }
    return texture(src,uv);
}

void fragment(){
    COLOR = gaussian_blur_h(TEXTURE ,TEXTURE_PIXEL_SIZE ,UV , 5.);
}

源码：
https://www.shadertoy.com/view/Mtl3Rj

高斯模糊

shader_type canvas_item;

float normpdf(in float x, in float sigma){
    return 0.39894*exp(-.5*x*x/(sigma*sigma))/sigma;
}

vec4 gaussian_blur(sampler2D src, vec2 size, vec2 uv, int m_size){
    vec4 cc = texture(src, uv);
    vec3 c = cc.rgb;
    int k_size = (m_size-1)/2;
    float sigma = 7.;
    vec3 final_color = vec3(0.);
    float z = 0.;
    for(int i=-k_size;i<=k_size;i++){
        float n = normpdf(float(i), sigma);
        z+=n;
        for(int j=-k_size;j<=k_size;j++){
            final_color+=n*n*texture(src,uv+size*vec2(float(i),float(j))).rgb;
        }
    }
    return vec4(final_color/z/z,1.);
}

void fragment(){
    COLOR = gaussian_blur(TEXTURE ,TEXTURE_PIXEL_SIZE ,UV , 10);
}

https://www.shadertoy.com/view/XdfGDH