Portal shader inspired by Portal 1

[created in Godot 4.6.2]

A fully procedural, unlit portal shader for Godot 4.x. No external textures are required!

This shader is highly customizable.

How to use:

Create a MeshInstance3D in your scene.
Assign a QuadMesh to it.
Create a new ShaderMaterial and assign this shader.
Tweak the uniform parameters in the inspector to create your unique portal!

Compatible with Godot 4.x.

Can easily be converted to a canvas_item shader for 2D games by changing shader_type spatial; to shader_type canvas_item; and replacing ALBEDO with COLOR.rgb and ALPHA with COLOR.a.

Shader code

shader_type spatial;
render_mode blend_mix, depth_draw_opaque, cull_disabled, unshaded, shadows_disabled, specular_disabled;

uniform vec3  portal_color      : source_color = vec3(0.15, 0.6, 1.0);
uniform vec3  ring_color_bottom : source_color = vec3(1.0, 1.0, 1.0);
uniform vec3  ring_color_top    : source_color = vec3(0.15, 0.6, 1.0);
uniform vec3  halo_color        : source_color = vec3(0.15, 0.6, 1.0);
uniform vec3  cloud_color_dark  : source_color = vec3(0.0, 0.1, 0.3);
uniform vec3  cloud_color_light : source_color = vec3(0.15, 0.6, 1.0);

uniform float brightness         : hint_range(0.5, 10.0) = 3.0;
uniform float ring_brightness    : hint_range(0.5, 10.0) = 2.5;
uniform float halo_brightness    : hint_range(0.0, 5.0)  = 0.7;
uniform float cloud_brightness   : hint_range(0.0, 5.0)  = 1.5;

uniform float oval_ratio         : hint_range(0.1, 1.0)  = 0.6;
uniform float body_edge_inner    : hint_range(0.5, 1.0)  = 0.92;
uniform float body_edge_outer    : hint_range(0.5, 1.0)  = 1.0;

uniform float ring_inner_start   : hint_range(0.5, 1.0)  = 0.83;
uniform float ring_inner_end     : hint_range(0.5, 1.0)  = 0.95;
uniform float ring_outer_start   : hint_range(0.8, 1.2)  = 0.97;
uniform float ring_outer_end     : hint_range(0.8, 1.5)  = 1.02;
uniform float ring_top_brightness: hint_range(0.0, 5.0)  = 1.2;

uniform float vertical_split_top : hint_range(-0.5, 0.5) = 0.15;
uniform float vertical_split_bot : hint_range(-0.5, 0.5) = -0.15;

uniform float halo_outer         : hint_range(1.0, 2.0)  = 1.12;
uniform float halo_inner         : hint_range(0.5, 1.2)  = 0.96;
uniform float halo_alpha_mult    : hint_range(0.0, 1.0)  = 0.7;

uniform float speed              : hint_range(0.0, 3.0)  = 1.0;
uniform float turbulence         : hint_range(0.5, 3.0)  = 1.0;

uniform float noise1_scale       : hint_range(1.0, 20.0) = 6.0;
uniform float noise1_speed_x     : hint_range(-1.0, 1.0) = 0.07;
uniform float noise1_speed_y     : hint_range(-1.0, 1.0) = 0.13;
uniform float noise1_weight      : hint_range(0.0, 1.0)  = 0.6;

uniform float noise2_scale       : hint_range(1.0, 20.0) = 12.0;
uniform float noise2_speed_x     : hint_range(-1.0, 1.0) = -0.11;
uniform float noise2_speed_y     : hint_range(-1.0, 1.0) = 0.09;
uniform float noise2_weight      : hint_range(0.0, 1.0)  = 0.4;

uniform float distort_strength   : hint_range(0.0, 0.5)  = 0.1;

uniform float cloud_threshold_low  : hint_range(0.0, 0.5)  = 0.15;
uniform float cloud_threshold_high : hint_range(0.5, 1.0)  = 0.9;
uniform float cloud_dark_level     : hint_range(0.0, 1.0)  = 0.05;

uniform int   fbm_octaves        : hint_range(1, 8)      = 5;

float hash(vec2 p){
    return fract(sin(dot(p, vec2(127.1, 311.7))) * 43758.5453);
}

float vnoise(vec2 p){
    vec2 i = floor(p);
    vec2 f = fract(p);
    f = f * f * (3.0 - 2.0 * f);
    return mix(mix(hash(i),             hash(i + vec2(1,0)), f.x),
               mix(hash(i + vec2(0,1)), hash(i + vec2(1,1)), f.x), f.y);
}

float fbm(vec2 p){
    float v = 0.0;
    float a = 0.5;
    for (int i = 0; i < 8; i++){
        if (i >= fbm_octaves) break;
        v += a * vnoise(p);
        p *= 2.0;
        a *= 0.5;
    }
    return v;
}

void fragment(){
    vec2 uv = UV - 0.5;

    vec2 e = uv * vec2(1.0 / oval_ratio, 1.0);
    float r = length(e) * 2.0;

    vec2 t1 = vec2(TIME * noise1_speed_x, TIME * noise1_speed_y) * speed;
    vec2 t2 = vec2(TIME * noise2_speed_x, TIME * noise2_speed_y) * speed;
    float n  = fbm(uv * noise1_scale * turbulence + t1) * noise1_weight
             + fbm(uv * noise2_scale * turbulence + t2) * noise2_weight;

    float dr = r + (n - 0.5) * distort_strength;

    float body   = 1.0 - smoothstep(body_edge_inner, body_edge_outer, dr);

    float ring   = smoothstep(ring_inner_start, ring_inner_end, dr)
                 - smoothstep(ring_outer_start, ring_outer_end, dr);

    float clouds = smoothstep(cloud_threshold_low, cloud_threshold_high, n);

    float bottom_mask = smoothstep(vertical_split_top, vertical_split_bot, uv.y);

    vec3 r_bottom = ring_color_bottom * brightness * ring_brightness;
    vec3 r_top    = ring_color_top    * brightness * ring_top_brightness;
    vec3 ring_col = mix(r_top, r_bottom, bottom_mask);

    vec3 inside_col = mix(cloud_color_dark * brightness,
                          cloud_color_light * cloud_brightness * brightness,
                          clouds);

    vec3 col = inside_col * body + ring_col * ring;

    float halo = smoothstep(halo_outer, halo_inner, r) * (1.0 - body) * clouds;
    col += halo_color * halo * brightness * halo_brightness;

    ALBEDO = col;
    ALPHA  = clamp(body + ring + halo * halo_alpha_mult, 0.0, 1.0);
}