void reorderList(ListNode *head) {
if(head == NULL)
return ;
ListNode * oneStep = head, * twoStep = head;
while(twoStep->next && twoStep->next->next)
{
oneStep = oneStep->next;
twoStep=twoStep->next->next;
}
ListNode * firstHalf = head;
ListNode * lastHalf = oneStep->next;
oneStep->next = NULL;
lastHalf = reverse(lastHalf,NULL);
ListNode dummyNode(INT_MAX);
ListNode * pre = & dummyNode;
while(firstHalf)
{
pre->next = firstHalf;
ListNode * tmp = firstHalf->next;
firstHalf->next = lastHalf;
pre = lastHalf;
firstHalf = tmp;
if(lastHalf!=NULL)
lastHalf = lastHalf->next;
}
}
//-----------------------------------------------------------------------------
const Matrix4& AutoParamDataSource::getSpotlightViewProjMatrix(size_t index) const
{
if (index < OGRE_MAX_SIMULTANEOUS_LIGHTS)
{
const Light& l = getLight(index);
if (&l != &mBlankLight &&
l.getType() == Light::LT_SPOTLIGHT &&
mSpotlightViewProjMatrixDirty[index])
{
Frustum frust;
SceneNode dummyNode(0);
dummyNode.attachObject(&frust);
frust.setProjectionType(PT_PERSPECTIVE);
frust.setFOVy(l.getSpotlightOuterAngle());
frust.setAspectRatio(1.0f);
// set near clip the same as main camera, since they are likely
// to both reflect the nature of the scene
frust.setNearClipDistance(mCurrentCamera->getNearClipDistance());
// Calculate position, which same as spotlight position, in camera-relative coords if required
dummyNode.setPosition(l.getDerivedPosition(true));
// Calculate direction, which same as spotlight direction
Vector3 dir = - l.getDerivedDirection(); // backwards since point down -z
dir.normalise();
Vector3 up = Vector3::UNIT_Y;
// Check it's not coincident with dir
if (Math::Abs(up.dotProduct(dir)) >= 1.0f)
{
// Use camera up
up = Vector3::UNIT_Z;
}
// cross twice to rederive, only direction is unaltered
Vector3 left = dir.crossProduct(up);
left.normalise();
up = dir.crossProduct(left);
up.normalise();
// Derive quaternion from axes
Quaternion q;
q.FromAxes(left, up, dir);
dummyNode.setOrientation(q);
// The view matrix here already includes camera-relative changes if necessary
// since they are built into the frustum position
mSpotlightViewProjMatrix[index] =
PROJECTIONCLIPSPACE2DTOIMAGESPACE_PERSPECTIVE *
frust.getProjectionMatrixWithRSDepth() *
frust.getViewMatrix();
mSpotlightViewProjMatrixDirty[index] = false;
}
return mSpotlightViewProjMatrix[index];
}
else
return Matrix4::IDENTITY;
}
ListNode *removeNthFromEnd(ListNode *head, int n) {
if( n == 0 )
return head;
ListNode dummyNode(0);
dummyNode.next = head;
ListNode * last = &dummyNode;
ListNode * before = &dummyNode;
for(int i = 0 ;i < n ;i++)
{
last = last->next;
}
while(last->next)
{
last = last->next;
before = before->next;
}
before->next = before->next->next;
return dummyNode.next;
}