Babybus-u3d技術(shù)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;
}
}
使用樣例
基于MeshFilter的3D拾取.png
看看就好识脆，效率有點低，建議直接用MeshCollider虐拓。
點和三角形相交的算法來源 ——
