public static void GetCullingPlanesAndSphere(out SPlanes planes, out AABB aabb, Matrix4x4 frustumMatrix, Matrix4x4 objTrans)
{
// From the objects that we are rendering from this camera.
// Cull it further to the objects that overlap with the Projector frustum
Matrix4x4 finalMatrix = frustumMatrix * objTrans;
planes = ExtractProjectionPlanes(finalMatrix);
aabb = ExtracetProjectionAABB(finalMatrix);
}
static SPlanes ExtractProjectionPlanes(Matrix4x4 finalMatrix)
{
//https://www.zhihu.com/question/46377273/answer/101213293
SPlanes outPlanes = new SPlanes();
const int kPlaneFrustumLeft = 0;
const int kPlaneFrustumRight = 1;
const int kPlaneFrustumBottom = 2;
const int kPlaneFrustumTop = 3;
const int kPlaneFrustumNear = 4;
const int kPlaneFrustumFar = 5;
//const int kPlaneFrustumNum = 6;
Vector4 tmpVec = new Vector4();
Vector4 otherVec = new Vector4();
tmpVec[0] = finalMatrix[3, 0];
tmpVec[1] = finalMatrix[3, 1];
tmpVec[2] = finalMatrix[3, 2];
tmpVec[3] = finalMatrix[3, 3];
otherVec[0] = finalMatrix[0, 0];
otherVec[1] = finalMatrix[0, 1];
otherVec[2] = finalMatrix[0, 2];
otherVec[3] = finalMatrix[0, 3];
// left & right
outPlanes[kPlaneFrustumLeft] = NormalizeUnsafe(new Vector3(otherVec[0] + tmpVec[0], otherVec[1] + tmpVec[1], otherVec[2] + tmpVec[2]), otherVec[3] + tmpVec[3]);
outPlanes[kPlaneFrustumRight] = NormalizeUnsafe(new Vector3(-otherVec[0] + tmpVec[0], -otherVec[1] + tmpVec[1], -otherVec[2] + tmpVec[2]), -otherVec[3] + tmpVec[3]);
// bottom & top
otherVec[0] = finalMatrix[1, 0];
otherVec[1] = finalMatrix[1, 1];
otherVec[2] = finalMatrix[1, 2];
otherVec[3] = finalMatrix[1, 3];
outPlanes[kPlaneFrustumBottom] = NormalizeUnsafe(new Vector3(otherVec[0] + tmpVec[0], otherVec[1] + tmpVec[1], otherVec[2] + tmpVec[2]), otherVec[3] + tmpVec[3]);
outPlanes[kPlaneFrustumTop] = NormalizeUnsafe(new Vector3(-otherVec[0] + tmpVec[0], -otherVec[1] + tmpVec[1], -otherVec[2] + tmpVec[2]), -otherVec[3] + tmpVec[3]);
otherVec[0] = finalMatrix[2, 0];
otherVec[1] = finalMatrix[2, 1];
otherVec[2] = finalMatrix[2, 2];
otherVec[3] = finalMatrix[2, 3];
// near & far
outPlanes[kPlaneFrustumNear] = NormalizeUnsafe(new Vector3(otherVec[0] + tmpVec[0], otherVec[1] + tmpVec[1], otherVec[2] + tmpVec[2]), otherVec[3] + tmpVec[3]);
outPlanes[kPlaneFrustumFar] = NormalizeUnsafe(new Vector3(-otherVec[0] + tmpVec[0], -otherVec[1] + tmpVec[1], -otherVec[2] + tmpVec[2]), -otherVec[3] + tmpVec[3]);
return(outPlanes);
}
bool IntersectAABBPlaneBounds(AABB a, SPlanes ps)
{
Vector3 m = a.m; // GetCenter(a.Min, a.Max);// a.GetCenter();// center of AABB
Vector3 extent = a.extent; // GetExtent(a.Min, a.Max);//a.GetExtent();// half-diagonal
for (int i = 0; i < 6; ++i)
{
Plane p = ps[i];
Vector3 normal = p.normal;
float dist = p.GetDistanceToPoint(m);
float radius = Vector3.Dot(extent, new Vector3(Mathf.Abs(normal.x), Mathf.Abs(normal.y), Mathf.Abs(normal.z)));
if (dist + radius <= 0)
{
return(false); // behind clip plane
}
}
return(true); // AABB intersects space bounded by planes
}
bool RightParallelepipedInFrustum(Vector4 Min, Vector4 Max, SPlanes frustum_planes)
{
bool inside = true;
//试视锥体的6个平面。
for (int i = 0; i < 6; i++)
{
//从8点找到最靠近平面的那个点，然后测试它是否在平面之后。
//如果是的话 - 那么对象不在视锥体的内部。
float d = Mathf.Max(Min.x * frustum_planes[i].normal.x, Max.x * frustum_planes[i].normal.x) +
Mathf.Max(Min.y * frustum_planes[i].normal.y, Max.y * frustum_planes[i].normal.y) +
Mathf.Max(Min.z * frustum_planes[i].normal.z, Max.z * frustum_planes[i].normal.z) +
frustum_planes[i].distance;
inside &= d > 0;
//return false; //with flag works faster
}
return(inside);
}