Godot: Slicer shader by Nozomu

shader_type canvas_item;

uniform vec4 first_color : hint_color = vec4(1.0);
uniform vec4 second_color : hint_color = vec4(0.0, 0.0, 0.0, 1.0);
uniform float position : hint_range(-1, 1) = 0.0;
uniform float shrink : hint_range(0.5, 8) = 4;
uniform bool flipped = false;

uniform float left_limit : hint_range(0.0, 1280.0) = 0.0;
uniform float right_limit : hint_range(0.0, 1280.0) = 1280.0;

uniform float ribbon_width : hint_range(0.0, 100.0) = 50.0;
uniform float ribbon_angle : hint_range(0.0, 1.5) = 0.0;
uniform vec2 ribbon_position = vec2(640, 360);

varying vec2 world_pos;

void vertex() {
    world_pos = VERTEX.xy;
}


void fragment() {
    if (world_pos.x < left_limit || world_pos.x > right_limit) {
        COLOR = vec4(0,0,0,0);
    }
    else if (world_pos.y < ribbon_position.y - ribbon_width - tan(ribbon_angle)*(world_pos.x - ribbon_position.x)) {
        COLOR = vec4(0,0,0,0);
    }
    else if (world_pos.y > ribbon_position.y  - tan(ribbon_angle)*(world_pos.x - ribbon_position.x)) {
        COLOR = vec4(0,0,0,0);
    }
    else {
        float pivot = position + 0.5;
        vec2 uv = UV - pivot;

        if ((uv.x < 0.0 && !flipped) || (uv.x > 0.0 && flipped)) {
            COLOR = vec4(0,0,0,0);
        } else {
            float shift = abs(uv.x) * shrink;
            COLOR = mix(first_color, second_color, shift);
        }
    }
}