revoconner · December 22, 2025 02:54
diff --git a/README.md b/README.md
diff --git a/FBXToPrimitiveCubesColliders.cs b/FBXToPrimitiveCubesColliders.cs
 /*
 Build colliders in DCC application like maya and blender
 Export and import it as fbx,
 Run the tool to convert
 ************
 Only supports cuboids shape,
 so build your colliders with cubes.
 ***********
 Full support of transform, rotation and scale in object space
 Does not support shear
 */


 using UnityEngine;
 using UnityEditor;
 using System.Collections.Generic;

 public class FBXToPrimitiveCubes : EditorWindow
 {
    private GameObject sourceObject;
    private bool removeMeshRenderer = true;
    private bool removeMeshFilter = true;
    private bool useSelection = true;

    [MenuItem("Tools/Colliders/FBX To Primitive Cubes")]
    public static void ShowWindow()
    {
        GetWindow<FBXToPrimitiveCubes>("FBX To Cubes");
    }

    private void OnGUI()
    {
        EditorGUILayout.LabelField("FBX to Primitive Cubes", EditorStyles.boldLabel);
        EditorGUILayout.Space();

        useSelection = EditorGUILayout.Toggle("Use Selection", useSelection);
        if (useSelection)
            sourceObject = Selection.activeGameObject;
        else
            sourceObject = (GameObject)EditorGUILayout.ObjectField("Source FBX", sourceObject, typeof(GameObject), true);

        removeMeshRenderer = EditorGUILayout.Toggle("Remove Mesh Renderer", removeMeshRenderer);
        removeMeshFilter = EditorGUILayout.Toggle("Remove Mesh Filter", removeMeshFilter);

        EditorGUILayout.Space();

        GUI.enabled = sourceObject != null;
        if (GUILayout.Button("Generate Primitive Cubes"))
            GenerateCubes();
        GUI.enabled = true;

        EditorGUILayout.Space();
        EditorGUILayout.HelpBox(
            "Instructions:\n" +
            "1. Build colliders as cubes in DCC (Maya/Blender)\n" +
            "2. Group them (Maya/3ds Max) or \n Put under an empty (Blender) named \n 'Collider' or 'Colliders'\n" +
            "3. Export as FBX and import into Unity\n" +
            "4. Bring the FBX into the scene, select it, and run this tool\n\n" +
            "Note: Only cuboid shapes supported. No shear.",
            MessageType.Info);
    }

    private void GenerateCubes()
    {
        // Find child named "collider" or "colliders" (case insensitive, whole word)
        Transform colliderContainer = FindColliderContainer(sourceObject.transform);
        if (colliderContainer == null)
        {
            Debug.LogWarning("No child named 'Collider' or 'Colliders' found.");
            return;
        }

        MeshFilter[] meshFilters = colliderContainer.GetComponentsInChildren<MeshFilter>(true);
        if (meshFilters.Length == 0)
        {
            Debug.LogWarning("No MeshFilters found under collider container.");
            return;
        }

        GameObject container = new GameObject("Colliders");
        container.transform.position = sourceObject.transform.position;
        Undo.RegisterCreatedObjectUndo(container, "Create Cube Container");

        int count = 0;
        foreach (MeshFilter mf in meshFilters)
        {
            Mesh mesh = mf.sharedMesh;
            if (mesh == null) continue;

            if (!ExtractCubeTransform(mesh, out Vector3 localPos, out Quaternion localRot, out Vector3 localScale))
            {
                Debug.LogWarning($"Failed to extract transform from {mf.name}");
                continue;
            }

            Transform src = mf.transform;
            Vector3 worldPos = src.TransformPoint(localPos);
            Quaternion worldRot = src.rotation * localRot;
            Vector3 worldScale = Vector3.Scale(localScale, src.lossyScale);

            count++;
            GameObject cube = GameObject.CreatePrimitive(PrimitiveType.Cube);
            cube.name = $"Box_Collider_{count}";
            cube.transform.SetParent(container.transform, false);
            cube.transform.position = worldPos;
            cube.transform.rotation = worldRot;
            cube.transform.localScale = worldScale;

            if (removeMeshRenderer)
                DestroyImmediate(cube.GetComponent<MeshRenderer>());

            if (removeMeshFilter)
                DestroyImmediate(cube.GetComponent<MeshFilter>());

            Undo.RegisterCreatedObjectUndo(cube, "Create Primitive Cube");
        }

        // Delete the collider container
        Undo.DestroyObjectImmediate(colliderContainer.gameObject);

        Debug.Log($"Generated {count} cubes.");
    }

    private Transform FindColliderContainer(Transform parent)
    {
        foreach (Transform child in parent)
        {
            string name = child.name.ToLowerInvariant();
            if (name == "collider" || name == "colliders")
                return child;
        }
        return null;
    }

    private bool ExtractCubeTransform(Mesh mesh, out Vector3 position, out Quaternion rotation, out Vector3 scale)
    {
        position = Vector3.zero;
        rotation = Quaternion.identity;
        scale = Vector3.one;

        Vector3[] verts = mesh.vertices;
        if (verts.Length == 0) return false;

        // Cube mesh has 24 verts (4 per face), reduce to 8 unique corners
        List<Vector3> unique = GetUniqueVertices(verts, 0.0001f);

        if (unique.Count != 8)
        {
            Debug.LogWarning($"Expected 8 vertices, got {unique.Count}. Using bounds fallback.");
            position = mesh.bounds.center;
            scale = mesh.bounds.size;
            return true;
        }

        // Center is average of all corners
        foreach (var v in unique)
            position += v;
        position /= 8f;

        Vector3 corner = unique[0];
        List<Vector3> others = new List<Vector3>();
        foreach (var v in unique)
        {
            if (v != corner)
                others.Add(v);
        }
        others.Sort((a, b) => Vector3.Distance(corner, a).CompareTo(Vector3.Distance(corner, b)));

        // Find 3 edges from corner using orthogonality (dot product ~0), not just distance
        // Avoids picking face diagonal when it's shorter than longest edge
        Vector3 e1 = others[0] - corner;

        Vector3 e2 = Vector3.zero;
        foreach (var v in others)
        {
            Vector3 candidate = v - corner;
            if (candidate == e1) continue;
            if (Mathf.Abs(Vector3.Dot(e1.normalized, candidate.normalized)) < 0.1f)
            {
                e2 = candidate;
                break;
            }
        }

        Vector3 e3 = Vector3.zero;
        Vector3 expectedDir = Vector3.Cross(e1, e2).normalized;
        foreach (var v in others)
        {
            Vector3 candidate = v - corner;
            if (Mathf.Abs(Mathf.Abs(Vector3.Dot(expectedDir, candidate.normalized)) - 1f) < 0.1f)
            {
                e3 = candidate;
                break;
            }
        }

        if (e2 == Vector3.zero || e3 == Vector3.zero)
        {
            Debug.LogWarning("Could not find orthogonal edges. Using bounds fallback.");
            position = mesh.bounds.center;
            scale = mesh.bounds.size;
            return true;
        }

        // Build rotation matrix from edge directions
        float s1 = e1.magnitude;
        float s2 = e2.magnitude;
        float s3 = e3.magnitude;

        Vector3 ax1 = e1 / s1;
        Vector3 ax2 = e2 / s2;
        Vector3 ax3 = e3 / s3;

        if (Vector3.Dot(Vector3.Cross(ax1, ax2), ax3) < 0)
            ax3 = -ax3;

        Matrix4x4 rotMat = new Matrix4x4();
        rotMat.SetColumn(0, new Vector4(ax1.x, ax1.y, ax1.z, 0));
        rotMat.SetColumn(1, new Vector4(ax2.x, ax2.y, ax2.z, 0));
        rotMat.SetColumn(2, new Vector4(ax3.x, ax3.y, ax3.z, 0));
        rotMat.SetColumn(3, new Vector4(0, 0, 0, 1));

        rotation = rotMat.rotation;
        scale = new Vector3(s1, s2, s3);

        return true;
    }

    private List<Vector3> GetUniqueVertices(Vector3[] verts, float tolerance)
    {
        List<Vector3> unique = new List<Vector3>();
        foreach (var v in verts)
        {
            bool found = false;
            foreach (var u in unique)
            {
                if (Vector3.Distance(v, u) < tolerance)
                {
                    found = true;
                    break;
                }
            }
            if (!found)
                unique.Add(v);
        }
        return unique;
    }
 }
	/*
	Build colliders in DCC application like maya and blender
	Export and import it as fbx,
	Run the tool to convert
	************
	Only supports cuboids shape,
	so build your colliders with cubes.
	***********
	Full support of transform, rotation and scale in object space
	Does not support shear
	*/


	using UnityEngine;
	using UnityEditor;
	using System.Collections.Generic;

	public class FBXToPrimitiveCubes : EditorWindow
	{
	private GameObject sourceObject;
	private bool removeMeshRenderer = true;
	private bool removeMeshFilter = true;
	private bool useSelection = true;

	[MenuItem("Tools/Colliders/FBX To Primitive Cubes")]
	public static void ShowWindow()
	{
	GetWindow<FBXToPrimitiveCubes>("FBX To Cubes");
	}

	private void OnGUI()
	{
	EditorGUILayout.LabelField("FBX to Primitive Cubes", EditorStyles.boldLabel);
	EditorGUILayout.Space();

	useSelection = EditorGUILayout.Toggle("Use Selection", useSelection);
	if (useSelection)
	sourceObject = Selection.activeGameObject;
	else
	sourceObject = (GameObject)EditorGUILayout.ObjectField("Source FBX", sourceObject, typeof(GameObject), true);

	removeMeshRenderer = EditorGUILayout.Toggle("Remove Mesh Renderer", removeMeshRenderer);
	removeMeshFilter = EditorGUILayout.Toggle("Remove Mesh Filter", removeMeshFilter);

	EditorGUILayout.Space();

	GUI.enabled = sourceObject != null;
	if (GUILayout.Button("Generate Primitive Cubes"))
	GenerateCubes();
	GUI.enabled = true;

	EditorGUILayout.Space();
	EditorGUILayout.HelpBox(
	"Instructions:\n" +
	"1. Build colliders as cubes in DCC (Maya/Blender)\n" +
	"2. Group them (Maya/3ds Max) or \n Put under an empty (Blender) named \n 'Collider' or 'Colliders'\n" +
	"3. Export as FBX and import into Unity\n" +
	"4. Bring the FBX into the scene, select it, and run this tool\n\n" +
	"Note: Only cuboid shapes supported. No shear.",
	MessageType.Info);
	}

	private void GenerateCubes()
	{
	// Find child named "collider" or "colliders" (case insensitive, whole word)
	Transform colliderContainer = FindColliderContainer(sourceObject.transform);
	if (colliderContainer == null)
	{
	Debug.LogWarning("No child named 'Collider' or 'Colliders' found.");
	return;
	}

	MeshFilter[] meshFilters = colliderContainer.GetComponentsInChildren<MeshFilter>(true);
	if (meshFilters.Length == 0)
	{
	Debug.LogWarning("No MeshFilters found under collider container.");
	return;
	}

	GameObject container = new GameObject("Colliders");
	container.transform.position = sourceObject.transform.position;
	Undo.RegisterCreatedObjectUndo(container, "Create Cube Container");

	int count = 0;
	foreach (MeshFilter mf in meshFilters)
	{
	Mesh mesh = mf.sharedMesh;
	if (mesh == null) continue;

	if (!ExtractCubeTransform(mesh, out Vector3 localPos, out Quaternion localRot, out Vector3 localScale))
	{
	Debug.LogWarning($"Failed to extract transform from {mf.name}");
	continue;
	}

	Transform src = mf.transform;
	Vector3 worldPos = src.TransformPoint(localPos);
	Quaternion worldRot = src.rotation * localRot;
	Vector3 worldScale = Vector3.Scale(localScale, src.lossyScale);

	count++;
	GameObject cube = GameObject.CreatePrimitive(PrimitiveType.Cube);
	cube.name = $"Box_Collider_{count}";
	cube.transform.SetParent(container.transform, false);
	cube.transform.position = worldPos;
	cube.transform.rotation = worldRot;
	cube.transform.localScale = worldScale;

	if (removeMeshRenderer)
	DestroyImmediate(cube.GetComponent<MeshRenderer>());

	if (removeMeshFilter)
	DestroyImmediate(cube.GetComponent<MeshFilter>());

	Undo.RegisterCreatedObjectUndo(cube, "Create Primitive Cube");
	}

	// Delete the collider container
	Undo.DestroyObjectImmediate(colliderContainer.gameObject);

	Debug.Log($"Generated {count} cubes.");
	}

	private Transform FindColliderContainer(Transform parent)
	{
	foreach (Transform child in parent)
	{
	string name = child.name.ToLowerInvariant();
	if (name == "collider" \|\| name == "colliders")
	return child;
	}
	return null;
	}

	private bool ExtractCubeTransform(Mesh mesh, out Vector3 position, out Quaternion rotation, out Vector3 scale)
	{
	position = Vector3.zero;
	rotation = Quaternion.identity;
	scale = Vector3.one;

	Vector3[] verts = mesh.vertices;
	if (verts.Length == 0) return false;

	// Cube mesh has 24 verts (4 per face), reduce to 8 unique corners
	List<Vector3> unique = GetUniqueVertices(verts, 0.0001f);

	if (unique.Count != 8)
	{
	Debug.LogWarning($"Expected 8 vertices, got {unique.Count}. Using bounds fallback.");
	position = mesh.bounds.center;
	scale = mesh.bounds.size;
	return true;
	}

	// Center is average of all corners
	foreach (var v in unique)
	position += v;
	position /= 8f;

	Vector3 corner = unique[0];
	List<Vector3> others = new List<Vector3>();
	foreach (var v in unique)
	{
	if (v != corner)
	others.Add(v);
	}
	others.Sort((a, b) => Vector3.Distance(corner, a).CompareTo(Vector3.Distance(corner, b)));

	// Find 3 edges from corner using orthogonality (dot product ~0), not just distance
	// Avoids picking face diagonal when it's shorter than longest edge
	Vector3 e1 = others[0] - corner;

	Vector3 e2 = Vector3.zero;
	foreach (var v in others)
	{
	Vector3 candidate = v - corner;
	if (candidate == e1) continue;
	if (Mathf.Abs(Vector3.Dot(e1.normalized, candidate.normalized)) < 0.1f)
	{
	e2 = candidate;
	break;
	}
	}

	Vector3 e3 = Vector3.zero;
	Vector3 expectedDir = Vector3.Cross(e1, e2).normalized;
	foreach (var v in others)
	{
	Vector3 candidate = v - corner;
	if (Mathf.Abs(Mathf.Abs(Vector3.Dot(expectedDir, candidate.normalized)) - 1f) < 0.1f)
	{
	e3 = candidate;
	break;
	}
	}

	if (e2 == Vector3.zero \|\| e3 == Vector3.zero)
	{
	Debug.LogWarning("Could not find orthogonal edges. Using bounds fallback.");
	position = mesh.bounds.center;
	scale = mesh.bounds.size;
	return true;
	}

	// Build rotation matrix from edge directions
	float s1 = e1.magnitude;
	float s2 = e2.magnitude;
	float s3 = e3.magnitude;

	Vector3 ax1 = e1 / s1;
	Vector3 ax2 = e2 / s2;
	Vector3 ax3 = e3 / s3;

	if (Vector3.Dot(Vector3.Cross(ax1, ax2), ax3) < 0)
	ax3 = -ax3;

	Matrix4x4 rotMat = new Matrix4x4();
	rotMat.SetColumn(0, new Vector4(ax1.x, ax1.y, ax1.z, 0));
	rotMat.SetColumn(1, new Vector4(ax2.x, ax2.y, ax2.z, 0));
	rotMat.SetColumn(2, new Vector4(ax3.x, ax3.y, ax3.z, 0));
	rotMat.SetColumn(3, new Vector4(0, 0, 0, 1));

	rotation = rotMat.rotation;
	scale = new Vector3(s1, s2, s3);

	return true;
	}

	private List<Vector3> GetUniqueVertices(Vector3[] verts, float tolerance)
	{
	List<Vector3> unique = new List<Vector3>();
	foreach (var v in verts)
	{
	bool found = false;
	foreach (var u in unique)
	{
	if (Vector3.Distance(v, u) < tolerance)
	{
	found = true;
	break;
	}
	}
	if (!found)
	unique.Add(v);
	}
	return unique;
	}
	}
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