I'm trying to use join_facet() iteratively to grow a single facet starting from a given facet_handle. However, I'm running into trouble when using the Halfedge_around_facet_circulator in combination with join_facet(). My while-loop does not become false anymore which works fine if I don't use join_facet() and the circulator seems to point to something else.
I assume that the join operation is somehow changing that Halfedge_around_facet_circulator. But why and how to solve this?
Polyhedron P_out; // is a valid pure triangle Polyhedron
bool merge_next = true;
while (merge_next == true) {
Polyhedron::Halfedge_around_facet_circulator hit = facet_handle->facet_begin(); // facet_handle pointing to facet of P_out
merge_next = false;
do {
if(!(hit->is_border_edge())) {
if (coplanar(hit->facet(), hit->opposite()->facet())) {
if (CGAL::circulator_size(hit->opposite()->vertex_begin()) >= 3 && CGAL::circulator_size(hit->vertex_begin()) >= 3
&& hit->facet()->id() != hit->opposite()->facet()->id()) {
Polyhedron::Halfedge_handle hit2 = hit;
P_out->join_facet(hit2);
merge_next = true;
}
}
}
} while (++hit != facet_handle->facet_begin());
}
What this code should do:
Given the facet_handle, iterate over the corresponding halfedges of facet and merge if possible. Then taking facet_handle of created new facet again and doing the same until no neighboring facets are left to merge.
Edit:
There are areas on which the code runs fine and others where it crashes at hit->is_border_edge() after the first join_facet().
Related
I get a Null Pointer Exception, and the trace tells me it is inside a function that I have. This function runs every frame and does some calculations and stuff. Anyway, the problem is that when I go to debug, stepping through each line, the function runs fine, and the error only comes up at the end of the draw loop.
This error only recently came up, and the changes I made don't have much to do with the function in question so...
The function mentioned in the trace detects if the object touches something, and acts on it.
Also, the trace gives a line number that does not exist, I'm guessing that's because of the Processing compiling.
I am using Processing 4 if that matters.
Here's the trace:
java.lang.NullPointerException
at ants$Ant.sense(ants.java:190)
at ants$Ant.go(ants.java:220)
at ants.draw(ants.java:44)
at processing.core.PApplet.handleDraw(PApplet.java:2201)
at processing.awt.PSurfaceAWT$10.callDraw(PSurfaceAWT.java:1422)
at processing.core.PSurfaceNone$AnimationThread.run(PSurfaceNone.java:354)
Thanks!
Edit:
More info: This is an ant simulator, and it crashes at food pickup. This used to work and broke while adding (seemingly) unrelated stuff. It crashes at food pickup, which is managed by the sense() function. The Food class only has a position and a render function.
Here is some code:
void sense() { // The problematic function
if (!detectFood && !carryFood) {
float closest = viewRadius;
Food selected = null;
for (Food fd : foods){
float foodDist = position.dist(fd.position);
if(foodDist <= viewRadius) {
if(foodDist < closest) {
selected = fd;
closest = foodDist;
}
}
}
if (selected != null){
detectFood = true;
foodFocused = selected;
}
} else {
if(position.dist(foodFocused.position) < 2*r) {
takeFood();
detectFood = false;
}
}
}
void draw() { // draw loop
background(51);
for (Food food : foods) {
food.render();
}
for (Ant ant : ants) {
ant.go();
}
for (int i=0; i < trails.size(); i++) {
Trail trail = trails.get(i);
if (trail.strenght <= 0)
trails.remove(trail);
else
trail.go();
}
}
The problem is not the trail, as it still crashes without it,
I've read somewhere that a variable should be entered into the code if it is reused. But when I write my code for logic transparency, I sometimes create intermediate variables (with names reflecting what they contain) which are used only once.
How incorrect is this concept?
PS:
I want to do it right.
It is important to note that most of the time clarity takes precedence over re-usability or brevity. This is one of the basic principles of clean code. Most modern compilers optimize code anyway so creating new variables need not be a concern at all.
It is perfectly fine to create a new variable if it would add clarity to your code. Make sure to give it a meaningful name. Consider the following function:
public static boolean isLeapYear(final int yyyy) {
if ((yyyy % 4) != 0) {
return false;
}
else if ((yyyy % 400) == 0) {
return true;
}
else if ((yyyy % 100) == 0) {
return false;
}
else {
return true;
}
}
Even though the boolean expressions are used only once, they may confuse the reader of the code. We can rewrite it as follows
public static boolean isLeapYear(int year) {
boolean fourth = year % 4 == 0;
boolean hundredth = year % 100 == 0;
boolean fourHundredth = year % 400 == 0;
return fourth && (!hundredth || fourHundredth);
}
These boolean variables add much more clarity to the code.
This example is from the Clean Code book by Robert C. Martin.
I am having some trouble with programming hit detection in Processing.JS. I have tried to make a function that checks if something is touching an object and returns true and otherwise returns false. This is that here.
Snake.prototype.checkTouching = function(v){
if(v.position.x > this.position.x - this.width/2 && v.position < this.position.x + this.width/2 && v.position.y > this.positon.y - this.height/2 && v.position.y < this.position.y + this.height/2){
return true;
}else{
return false;
}
};
I am implementing it by creating a new variable "b" in my draw function that holds the value the function returned then using an if statement to check if the value "b" is holding is true. Like so
var b = snakey.checkTouching(mos);
var restarts = 0;
if(b === true){
restarts += 1;
Program.restart();
}
unfortunately even when the object the function is running on is touching the object that is running it nothing happens. I have already checked to see if the logic works and it is valid so I know it has to be my implementation I just can not seem to find out what is wrong with my implementation. Can anyone tell what I am doing wrong? Full program here.Full Program
I have a web service that interfaces with the google maps API to generate a polygon on a google map. The service takes the GPS values and stores them for retrieval.
The problem is that when I try and use these values on my iPhone app the MKPolyline is just either a mess or a bunch of zig-zag lines.
Is there a way to make sense of these values so I can reconstruct the polygon?
My current code looks like this
private void GenerateMap()
{
var latCoord = new List<double>();
var longCoord = new List<double>();
var pad = AppDelegate.Self.db.GetPaddockFromCrop(crop);
mapMapView.MapType = MKMapType.Standard;
mapMapView.ZoomEnabled = true;
mapMapView.ScrollEnabled = false;
mapMapView.OverlayRenderer = (m, o) =>
{
if (o.GetType() == typeof(MKPolyline))
{
var p = new MKPolylineRenderer((MKPolyline)o);
p.LineWidth = 2.0f;
p.StrokeColor = UIColor.Green;
return p;
}
else
return null;
};
scMapType.ValueChanged += (s, e) =>
{
switch (scMapType.SelectedSegment)
{
case 0:
mapMapView.MapType = MKMapType.Standard;
break;
case 1:
mapMapView.MapType = MKMapType.Satellite;
break;
case 2:
mapMapView.MapType = MKMapType.Hybrid;
break;
}
};
if (pad.Boundaries != null)
{
var bounds = pad.Boundaries.OrderBy(t => t.latitude).ThenBy(t => t.longitude).ToList();
foreach (var l in bounds)
{
double lat = l.latitude;
double lon = l.longitude;
latCoord.Add(lat);
longCoord.Add(lon);
}
if (latCoord.Count != 0)
{
if (latCoord.Count > 0)
{
var coord = new List<CLLocationCoordinate2D>();
for (int i = 0; i < latCoord.Count; ++i)
{
var c = new CLLocationCoordinate2D();
c.Latitude = latCoord[i];
c.Longitude = longCoord[i];
coord.Add(c);
}
var line = MKPolyline.FromCoordinates(coord.ToArray());
mapMapView.AddOverlay(line);
mapMapView.SetVisibleMapRect(line.BoundingMapRect, true);
}
}
}
}
MKPolygon / MKPolygonRenderer gives the same sort of random line mess. The OrderBy LINQ makes no difference other than to make the random lines a zig-zag going up or down the view.
Since you don't know the order the points were captured in, you can't trace the actual path traveled around the perimeter of the paddock; this is why your polylines are turning into silly-walks all over the map. Lacking that information, you can at best make an educated guess.
Some possible heuristics you might want to try:
Take the average of all the points to get a "somewhere in the middle" point, then order by atan2(l.latitude - middle.latitude, l.longitude - middle.longitude). (Be careful, atan2 is undefined at (0, 0)!)
Take the convex hull of the points captured: for a relatively small number of points you can get away with the simple quadratic time Jarvis's march. This has the approximate effect of wrapping a notional rubber band around the outside of the map push-pins by discarding points that would form concavities, and should also give you the order of the remaining points.
I'm messing around with the PushSource sample filter shipped with the DirectShow SDK and I'm having the following problem:
When I call IMediaControl::Run(), it returns S_FALSE which means "the graph is preparing to run, but some filters have not completed the transition to a running state". MSDN suggests to then call IMediaControl::GetState() and wait for the transition to finish.
And so, I call IMediaControl::GetState(INFINITE, ...) which is supposed to solve the problem.
However, to the contrary, it returns VFW_S_STATE_INTERMEDIATE even though I've specified an infinite waiting time.
I've tried all three variations (Bitmap, Bitmap Set and Desktop) and they all behave the same way, which initially lead me to believe there is a bug in there somewhere.
However, then, I tried using IFilterGraph::AddSourceFilter to do the same and it did the same thing, which must mean it's my rendering code that is the problem:
CoInitialize(0);
IGraphBuilder *graph = 0;
assert(S_OK == CoCreateInstance(CLSID_FilterGraph, 0, CLSCTX_INPROC_SERVER, IID_IGraphBuilder, (void**)&graph));
IBaseFilter *pushSource = 0;
graph->AddSourceFilter(L"sample.bmp", L"Source", &pushSource);
IPin *srcOut = 0;
assert(S_OK == GetPin(pushSource, PINDIR_OUTPUT, &srcOut));
graph->Render(srcOut);
IMediaControl *c = 0;
IMediaEvent *pEvent;
assert(S_OK == graph->QueryInterface(IID_IMediaControl, (void**)&c));
assert(S_OK == graph->QueryInterface(IID_IMediaEvent, (void**)&pEvent));
HRESULT hr = c->Run();
if(hr != S_OK)
{
if(hr == S_FALSE)
{
OAFilterState state;
hr = c->GetState(INFINITE, &state);
assert(hr == S_OK );
}
}
long code;
assert(S_OK == pEvent->WaitForCompletion(INFINITE, &code));
Anyone knows how to fix this?
IBaseFilter *pushSource = 0;
graph->AddSourceFilter(L"sample.bmp", L"Source", &pushSource);
AddSourceFilter adds a default source filter, I don't think it will add your pushsource samplefilter.
I would recommend to add the graph to the ROT, so you can inspect it with graphedit.
And what happens if you don't call GetState()?
hr = pMediaControl->Run();
if(FAILED(hr)) {
/// handle error
}
long evCode=0;
while (evCode == 0)
{
pEvent->WaitForCompletion(1000, &evCode);
/// other code
}
Open GraphEditPlus, add your filter, render its pin and press Run. Then you'll see states of each filter separately, so you'll see what filter didn't run and why.