// Netting for the goal pocket.
//
// Applied to a box viewed from the inside (cull_front), so one mesh gives a
// five-sided pocket of netting rather than a flat panel across the back. The
// strand pattern is driven from model-space position rather than UV so spacing
// stays physical and continuous across all five faces — a box's UV layout
// would stretch it differently on each.
//
// Cut with discard rather than alpha blending on purpose: an alpha-scissor net
// still writes depth, so it sorts against the pocket, the frame and the
// arena's containment field like ordinary solid geometry. A blended net would
// join the transparent queue and sort per-object against the boundary shell,
// which is the class of artefact this whole pass removed.
shader_type spatial;
render_mode cull_front, diffuse_burley;

uniform vec3 net_color : source_color = vec3(0.65, 0.78, 1.0);
uniform float cell_size = 0.13;
uniform float strand_width = 0.011;
uniform float emission_strength : hint_range(0.0, 4.0) = 0.35;

varying vec3 v_local;
varying vec3 v_local_normal;

void vertex() {
	v_local = VERTEX;
	v_local_normal = NORMAL;
}

// Distance to the nearest strand centre line of a square lattice.
float strand(vec2 p) {
	vec2 d = abs(fract(p / cell_size) - 0.5) * cell_size;
	return min(d.x, d.y);
}

void fragment() {
	vec3 n = abs(normalize(v_local_normal));
	// Project onto whichever plane this face lies in.
	float d = n.x > max(n.y, n.z)
		? strand(v_local.zy)
		: (n.y > n.z ? strand(v_local.xz) : strand(v_local.xy));
	if (d > strand_width) {
		discard;
	}
	// Only back faces survive cull_front, and their normals point out of the
	// pocket rather than into it, so flip them or the netting lights from
	// behind and reads flat black.
	if (!FRONT_FACING) {
		NORMAL = -NORMAL;
	}
	ALBEDO = net_color * 0.25;
	EMISSION = net_color * emission_strength;
	ROUGHNESS = 0.65;
	METALLIC = 0.1;
}