Desaturation Shader
Very simple 2D Desaturation Shader based on color perception that keep the overal “brightness” of the sprite. You can adjust the desaturation using the “saturation” uniform.
Shader code
shader_type canvas_item;
uniform float saturation;
void fragment() {
vec4 tex_color = texture(TEXTURE, UV);
COLOR.rgb = mix(vec3(dot(tex_color.rgb, vec3(0.299, 0.587, 0.114))), tex_color.rgb, saturation);
COLOR.a = tex_color.a;
}