brickcraft/Assets/Scripts/Utils/TangentSpaceVisualizer.cs

using UnityEngine;

public class TangentSpaceVisualizer : MonoBehaviour {

	public float offset = 0.01f;
	public float scale = 0.1f;

	void OnDrawGizmos () {
		MeshFilter filter = GetComponent<MeshFilter>();
		if (filter) {
			Mesh mesh = filter.sharedMesh;
			if (mesh) {
				ShowTangentSpace(mesh);
			}
		}
	}

	void ShowTangentSpace (Mesh mesh) {
		Vector3[] vertices = mesh.vertices;
		Vector3[] normals = mesh.normals;
		Vector4[] tangents = mesh.tangents;
		for (int i = 0; i < vertices.Length; i++) {
			ShowTangentSpace(
				transform.TransformPoint(vertices[i]),
				transform.TransformDirection(normals[i]),
				transform.TransformDirection(tangents[i]),
				tangents[i].w
			);
		}
	}

	void ShowTangentSpace (
		Vector3 vertex, Vector3 normal, Vector3 tangent, float binormalSign
	) {
		vertex += normal * offset;
		Gizmos.color = Color.green;
		Gizmos.DrawLine(vertex, vertex + normal * scale);
		Gizmos.color = Color.red;
		Gizmos.DrawLine(vertex, vertex + tangent * scale);
		Vector3 binormal = Vector3.Cross(normal, tangent) * binormalSign;
		Gizmos.color = Color.blue;
		Gizmos.DrawLine(vertex, vertex + binormal * scale);
	}
}