shader_type canvas_item;

global uniform float time;

const int SCRIBBLES = 4;

uniform sampler2D albedo_texture;
uniform bool use_linear_color_space = false;
uniform float scribble_switch_speed = 3.0;
uniform float scribble_intensity = 0.05;

group_uniforms ScribbleTextures;
uniform sampler2D scribbles_1 : hint_normal;
uniform sampler2D scribbles_2 : hint_normal;
uniform sampler2D scribbles_3 : hint_normal;
uniform sampler2D scribbles_4 : hint_normal;


void fragment() {
	// Called for every pixel the material is visible on.
	float wrapped_time = mod(time * scribble_switch_speed, float(SCRIBBLES));
	vec2 uv = UV;

	vec3 scribbles;
	switch (int(wrapped_time))
	{
		case 0:
			scribbles = texture(scribbles_1, uv).rgb;
			break;
		case 1:
			scribbles = texture(scribbles_2, uv).rgb;
			break;
		case 2:
			scribbles = texture(scribbles_3, uv).rgb;
			break;
		case 3:
			scribbles = texture(scribbles_4, uv).rgb;
			break;
	}

	uv.x += (scribbles.x - 0.5) * scribble_intensity;
	uv.y += (scribbles.y - 0.5) * scribble_intensity;

	vec4 tex = texture(albedo_texture, uv);

	if (use_linear_color_space)
		tex.rgb = pow(tex.rgb, vec3(2.0)); // sRGB to linear
		// linear to sRGB: tex.rgb =  pow(tex.rgb, vec3(1.0 / 2.2));

	COLOR = tex;
	//COLOR.rgb = scribbles;
}