基于MeshFilter的3D拾取

Babybus-u3d技术交流-基于MeshFilter的3D拾取

     public static class RendererExtension

{

    public static bool Raycast(this Renderer renderer, Ray ray)

    {

        if (renderer.GetComponent<MeshFilter>() == null)

            return false;



        Mesh mesh = renderer.GetComponent<MeshFilter>().mesh;



        float t = 0, u = 0, v = 0;

        for (int i = 0; i < mesh.triangles.Length / 3; i++)

        {

            Vector3 v0 = (renderer.transform.rotation * (Matrix4x4.Scale(renderer.transform.lossyScale) * mesh.vertices[mesh.triangles[i * 3]])) + renderer.transform.position;

            Vector3 v1 = (renderer.transform.rotation * (Matrix4x4.Scale(renderer.transform.lossyScale) * mesh.vertices[mesh.triangles[i * 3 + 1]])) + renderer.transform.position;

            Vector3 v2 = (renderer.transform.rotation * (Matrix4x4.Scale(renderer.transform.lossyScale) * mesh.vertices[mesh.triangles[i * 3 + 2]])) + renderer.transform.position;



            if (IntersectTriangle(ray, v0, v1, v2, ref t, ref u, ref v))

                return true;

        }



        return false;

    }



    private static bool IntersectTriangle(Ray ray, Vector3 v0, Vector3 v1, Vector3 v2, ref float t, ref float u, ref float v, bool cullface = true)

    {

        // Find vectors for two edges sharing vert0

        Vector3 edge1 = v1 - v0;

        Vector3 edge2 = v2 - v0;



        // Begin calculating determinant - also used to calculate U parameter

        Vector3 pvec = Vector3.Cross(ray.direction, edge2);



        // If determinant is near zero, ray lies in plane of triangle

        float det = Vector3.Dot(edge1, pvec);



        if (cullface)

        {

            if (det < 0.0001f)

                return false;

        }

        else

        {

            if (det > -0.0001f && det < 0.0001f)

                return false;

        }



        Vector3 tvec = ray.origin - v0;

        // Calculate U parameter and test bounds

        u = Vector3.Dot(tvec, pvec);

        if (u < 0.0f || u > det)

            return false;



        // Prepare to test V parameter

        Vector3 qvec = Vector3.Cross(tvec, edge1);



        // Calculate V parameter and test bounds

        v = Vector3.Dot(ray.direction, qvec);

        if (v < 0.0f || u + v > det)

            return false;



        // Calculate t, scale parameters, ray intersects triangle

        t = Vector3.Dot(edge2, qvec);

        float fInvDet = 1.0f / det;

        t *= fInvDet;

        u *= fInvDet;

        v *= fInvDet;



        return true;

    }

}

使用样例

基于MeshFilter的3D拾取.png

看看就好，效率有点低，建议直接用MeshCollider。

点和三角形相交的算法来源 ——