Godot Panorama Shader

shader_type spatial;
render_mode unshaded, depth_draw_always;

uniform sampler2D background: source_color, filter_linear;

vec4 getEnvironment(vec3 rayDirection) {
    const float PIm2 = 2.0 * PI;
    rayDirection = normalize(rayDirection);
    return texture(background, vec2((atan(rayDirection.z, rayDirection.x) / PIm2) - 0.25, acos(-rayDirection.y) / PI));
}

void fragment() {
    vec4 world_view = INV_VIEW_MATRIX * vec4(VIEW, 0);
    vec4 bg_color = getEnvironment(world_view.xyz);
    ALBEDO = bg_color.rgb;
    ALPHA = bg_color.a;
}