Godot Shader - proximity fade with alpha clip

shader_type spatial;
render_mode blend_mix,depth_draw_always, cull_disabled,diffuse_burley,specular_schlick_ggx;

uniform vec4 albedo : hint_color;
uniform sampler2D texture_albedo : hint_albedo;
uniform float specular = 0.5;
uniform float metallic = 0;
uniform float proximity_fade_distance = 0.85;
uniform float roughness : hint_range(0,1) = 1;
uniform float alpha_clip : hint_range(0,1) = 0.85;
uniform float point_size : hint_range(0,128) = 1;
uniform vec4 transmission : hint_color;
uniform sampler2D texture_transmission : hint_black;
uniform vec3 uv1_scale = vec3(1,1,1);
uniform vec3 uv1_offset = vec3(0,0,0);
uniform vec3 uv2_scale = vec3(1,1,1);
uniform vec3 uv2_offset = vec3(0,0,0);

void vertex() {
	UV=UV*uv1_scale.xy+uv1_offset.xy;
}

void fragment() {
	vec2 base_uv = UV;
	vec4 albedo_tex = texture(texture_albedo,base_uv);
	float alpha_tex = albedo_tex.a;
	if(alpha_tex < alpha_clip)
		alpha_tex = 0f;
	ALBEDO = albedo.rgb * albedo_tex.rgb;
	METALLIC = metallic;
	ROUGHNESS = roughness;
	SPECULAR = specular;
	float opacity = albedo.a * alpha_tex;
	float depth_tex = textureLod(DEPTH_TEXTURE,SCREEN_UV,0.0).r;
	vec4 world_pos = INV_PROJECTION_MATRIX * vec4(SCREEN_UV*2.0-1.0,depth_tex*2.0-1.0,1.0);
	world_pos.xyz/=world_pos.w;
	opacity*=clamp(1.0-smoothstep(world_pos.z+proximity_fade_distance,world_pos.z,VERTEX.z),0.0,1.0);
	vec3 transmission_tex = texture(texture_transmission,base_uv).rgb;
	TRANSMISSION = (transmission.rgb+transmission_tex);
 
	ALPHA = opacity;
	// skip drawing all pixels below this limit
	if (opacity < 0.001f)
		discard;
}