// Roblox in Godot 4.4 - part surface shader

shader_type spatial;

uniform sampler2D image : source_color;

uniform vec3 size = vec3(1.0, 1.0, 2.0);
uniform vec3 color = vec3(1.0, 1.0, 1.0);

uniform int back_surface = 3;
uniform int bottom_surface = 3;
uniform int front_surface = 3;
uniform int left_surface = 3;
uniform int right_surface = 3;
uniform int top_surface = 3;

varying vec3 face_normal;


void SetOffsetAndSize(int surface_type, inout vec2 offset)
{
	// smooth
	if (surface_type == 0) {
		discard;
	// glue
	} else if (surface_type == 1) {
		offset = vec2(0.0, 0.7);
	// weld
	} else if (surface_type == 2) {
		offset = vec2(0.0, 0.5);
	// studs
	} else if (surface_type == 3) {
		offset = vec2(0.0, 0.0);
	// inlet
	} else if (surface_type == 4) {
		offset = vec2(0.0, 0.3);
	// universal
	} else if (surface_type == 5) {
		offset = vec2(0.0, 0.9);
	} else {
		discard;
	}
}

void vertex() {
	face_normal = NORMAL;
}

void fragment() {
	vec3 normal_dir = normalize(face_normal);
	vec2 offset = vec2(0, 0);
	vec2 uv_size = vec2(0, 0);
	int surface_type = 0;
	
	// top
	if (normal_dir.y > 0.5) {
	
		surface_type = top_surface;
		uv_size = vec2(size.x, size.z);
		
	// right (+x)
	} else if (normal_dir.x > 0.5) {
	
		surface_type = right_surface;
		uv_size = vec2(size.z, size.y);
		
	// backward (+z)
	} else if (normal_dir.z > 0.5) {
	
		surface_type = back_surface;
		uv_size = vec2(size.x, size.y);
		
	// left (-x)
	} else if (normal_dir.x < 0.0) {
	
		surface_type = left_surface;
		uv_size = vec2(size.z, size.y);
		
	// bottom
	} else if (normal_dir.y < 0.0) {
	
		surface_type = bottom_surface;
		uv_size = vec2(size.x, size.z);
		
	// forward (-z)
	} else if (normal_dir.z < 0.0) {
	
		surface_type = front_surface;
		uv_size = vec2(size.x, size.y);
		
	} else {
		discard;
	}
	
	vec2 base_uv = (UV / vec2((64.0 / uv_size.x / 100.0), 10.0 / uv_size.y));
	
	base_uv += vec2(-0.025 * uv_size.x, 0.0);
	base_uv = mod(base_uv, vec2(1.0, 0.1));
	
	SetOffsetAndSize(surface_type, offset);
	base_uv += offset;
	
	vec4 albedo_tex = texture(image, base_uv);
	ALBEDO = albedo_tex.rgb;
	ALPHA = albedo_tex.a * 1.0;
}