shader_type spatial;
render_mode unshaded, fog_disabled, depth_draw_never, depth_test_disabled, cull_disabled;

// Screen-space ink outline: detects depth and normal discontinuities and
// draws thin dark edges over the scene — the drawn-line pass that unifies
// every model (kit, hero, character) into the cel look. Attach to a
// fullscreen quad (POSITION override) so it runs for whatever camera renders.

uniform sampler2D screen_tex : hint_screen_texture, filter_linear;
uniform sampler2D depth_tex : hint_depth_texture, filter_nearest;
uniform sampler2D normal_tex : hint_normal_roughness_texture, filter_nearest;

uniform vec4 ink_color : source_color = vec4(0.07, 0.06, 0.09, 1.0);
uniform float depth_threshold : hint_range(0.0, 4.0) = 1.1;
uniform float normal_threshold : hint_range(0.0, 1.0) = 0.55;
uniform float edge_strength : hint_range(0.0, 1.0) = 0.8;
uniform float max_distance : hint_range(10.0, 500.0) = 220.0;

float linear_depth(vec2 uv, mat4 inv_proj) {
	float d = texture(depth_tex, uv).r;
	vec4 ndc = vec4(uv * 2.0 - 1.0, d, 1.0);
	vec4 view = inv_proj * ndc;
	return -view.z / view.w;
}

void vertex() {
	POSITION = vec4(VERTEX.xy, 1.0, 1.0);
}

void fragment() {
	vec2 px = 1.0 / VIEWPORT_SIZE;
	vec2 uv = SCREEN_UV;

	float dc = linear_depth(uv, INV_PROJECTION_MATRIX);
	float dl = linear_depth(uv - vec2(px.x, 0.0), INV_PROJECTION_MATRIX);
	float dr = linear_depth(uv + vec2(px.x, 0.0), INV_PROJECTION_MATRIX);
	float du = linear_depth(uv - vec2(0.0, px.y), INV_PROJECTION_MATRIX);
	float dd = linear_depth(uv + vec2(0.0, px.y), INV_PROJECTION_MATRIX);

	// Depth edge: neighbor difference scaled by distance so far geometry
	// doesn't dissolve into noise.
	float ddiff = abs(dl - dr) + abs(du - dd);
	float depth_edge = step(depth_threshold * (0.5 + dc * 0.08), ddiff);

	// Normal edge: crease lines on same-depth corners.
	vec3 nc = texture(normal_tex, uv).xyz * 2.0 - 1.0;
	vec3 nl = texture(normal_tex, uv - vec2(px.x, 0.0)).xyz * 2.0 - 1.0;
	vec3 nu = texture(normal_tex, uv - vec2(0.0, px.y)).xyz * 2.0 - 1.0;
	float ndiff = length(nc - nl) + length(nc - nu);
	float normal_edge = step(normal_threshold, ndiff) * step(ddiff, depth_threshold);

	float fade = 1.0 - smoothstep(max_distance * 0.6, max_distance, dc);
	float edge = max(depth_edge, normal_edge * 0.6) * edge_strength * fade;

	vec3 scene = texture(screen_tex, uv).rgb;
	ALBEDO = mix(scene, ink_color.rgb, edge);
}