Balatro Foil card effect
Foil card effect ported to Godot 4.4, might not be perfect.
Best effects achieved by adding a Sprite2D (or ColorRect) node as a child of the card and applying the shader to it.
Shader code
shader_type canvas_item;
uniform highp vec2 offset;
uniform highp float speed : hint_range(0, 1) = 1.;
vec4 effect(sampler2D tex, vec2 texture_coords) {
vec4 texel = texture(tex, texture_coords);
vec2 uv = texture_coords;
vec2 adjusted_uv = uv - vec2(0.5, 0.5);
float low = min(texel.r, min(texel.g, texel.b));
float high = max(texel.r, max(texel.g, texel.b));
float delta = min(high, max(0.5, 1. - low));
vec2 foil = vec2(TIME / (1. / speed) + offset.x, offset.y);
float fac = max(min(2. * sin((length(90. * adjusted_uv) + foil.r * 2.) + 3. * (1. + 0.8 * cos(length(113.1121 * adjusted_uv) - foil.r * 3.121))) - 1. - max(5. - length(90. * adjusted_uv), 0.), 1.), 0.);
vec2 rotater = vec2(cos(foil.r * 0.1221), sin(foil.r * 0.3512));
float angle = dot(rotater, adjusted_uv) / (length(rotater) * length(adjusted_uv));
float fac2 = max(min(5. * cos(foil.g * 0.3 + angle * 3.14*(2.2 + 0.9*sin(foil.r * 1.65 + 0.2 * foil.g))) - 4. - max(2.-length(20.*adjusted_uv), 0.), 1.), 0.);
float fac3 = 0.3 * max(min(2. * sin(foil.r * 5. + uv.x * 3. + 3. * (1. + 0.5 * cos(foil.r * 7.))) - 1., 1.), -1.);
float fac4 = 0.3 * max(min(2. * sin(foil.r * 6.66 + uv.y * 3.8 + 3. * (1. + 0.5 * cos(foil.r * 3.414))) - 1., 1.), -1.);
float maxfac = max(max(fac, max(fac2, max(fac3, max(fac4, 0.0)))) + 2.2 * (fac + fac2 + fac3 + fac4), 0.);
texel.r = texel.r - delta + delta * maxfac * 0.3;
texel.g = texel.g - delta + delta * maxfac * 0.3;
texel.b = texel.b + delta * maxfac * 1.9;
texel.a = min(texel.a, 0.3 * texel.a + 0.9 * min(0.5, maxfac * 0.1));
return texel;
}
void fragment() {
COLOR *= effect(TEXTURE, UV.xy);
}