Super Mario World Transition

This is a post-processing shader adapted for Godot’s CanvasItem that simulates the iconic level transition or scene wipe seen in games like Super Mario World and other classic 16-bit titles.

The effect works in two distinct phases controlled by the progress_trans uniform:

Pixelation: As the transition starts (progress_trans goes from 0.0 to approx 0.66), the SCREEN_TEXTURE is rendered at an increasingly lower resolution (res), creating a blocky, pixelated look.
Color Fade: As the pixelation peaks (progress_trans goes from approx 0.66 to 1.0), the pixelated image is smoothly blended toward a solid transition_color, completing the scene change.

Adjustable Uniforms (Shader Parameters):

Parameter	Type	Description
progress_trans	`float`	The Master Control (0.0 to 1.0). Drives the entire transition from start (0.0) through pixelation to the final color fade (1.0).
transition_color	`vec4`	The final solid color the screen fades to (e.g., black, white, or a specific scene color).
SCREEN_TEXTURE	`sampler2D`	Required Input: Automatically provides the rendered view of the scene before the transition begins.

Shader code

shader_type canvas_item;
uniform sampler2D SCREEN_TEXTURE : hint_screen_texture, filter_linear_mipmap;
uniform float progress_trans : hint_range(0.0, 1.0);
uniform vec4 transition_color : source_color;


void fragment() {
    float t = progress_trans * 3.0;
    vec2 iResolution = 1.0 / SCREEN_PIXEL_SIZE;
    vec2 uv = SCREEN_UV;
    float _Speed = 15.0;
    float res = floor(pow(t, 1.4) * _Speed) * 2.0 + 0.01;
    uv *= iResolution / res;
    uv = floor(uv);
    uv /= iResolution / res;
    uv += res * 0.002;
    vec4 texture_pixelada = texture(SCREEN_TEXTURE, uv);
    float fade_start = 1.0; 
    float fade_end = 2.0;  
    float mix_factor = smoothstep(fade_start, fade_end, t);
    COLOR = mix(texture_pixelada, transition_color, mix_factor);
}