Qt Quick 3D - Custom Materials Example

 void MAIN()
 {
     vec2 size = vec2(textureSize(SCREEN_TEXTURE, 0));
     vec2 uv = FRAGCOORD.xy / size;

     vec3 view = normalize(VIEW_VECTOR);
     vec3 projection = view - view * normalize(NORMAL);
     vec3 refraction = projection * projection;
     uv += refraction.xy * 0.5;

     vec3 col = texture(SCREEN_TEXTURE, uv).rgb;
     col = col * 0.8 + vec3(0.2);

     BASE_COLOR = vec4(col, 1.0);
 }