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,
Related
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().
So i got this problem when one - two+ players are online the countdown timer goes in minus like this 4,3,2,1,0 -1,-2,-3 etc.
Does anyone know how i can fix this, been struggling with it for quite a long time now :P
Here is my countdown class:
#Override
public void run() {
if (timeUntilStart == 0) {
if (!Game.canStart()) {
if(Bukkit.getOnlinePlayers().size() <= 2) {
plugin.restartCountdown();
ChatUtilities.broadcast(ChatColor.RED + "Not enough players to start. Countdown will");
ChatUtilities.broadcast(ChatColor.RED + "restart.");
for (Player p : Bukkit.getOnlinePlayers()) p.playSound(p.getLocation(), Sound.ENDERDRAGON_WINGS, 5, 1);
return;
}else{
if(Game.canStart()) {
if(Bukkit.getOnlinePlayers().size() >= 2) {
Game.start();
}
}
}
}
}
boolean broadcast = false;
for (Player p : Bukkit.getOnlinePlayers()) {
p.setLevel(timeUntilStart);
if (timeUntilStart < 11 || timeUntilStart == 120 ||timeUntilStart == 60 || timeUntilStart == 30) {
p.playSound(p.getLocation(), Sound.ORB_PICKUP, 5, 0);
if (timeUntilStart == 1) p.playSound(p.getLocation(), Sound.ORB_PICKUP, 5, 1);
broadcast = true;
}
}
if (broadcast) ChatUtilities.broadcast(String.valueOf(timeUntilStart) + " ยง6Seconds until the game starts!");{
}
{
timeUntilStart -= 1;
}
}
}
The only case in which your method returns and timeUtilStart is not decremented is
timeUntilStart == 0 && !Game.canStart() && Bukkit.getOnlinePlayers().size() <= 2
As defined by the first three if blocks in your code.
This explains why your countdown does not stop when you have 3 or more players around.
I believe this mistake happened because of messy {} blocks and indentation. Take a step back and closely read the code you wrote again and fix brackets as well as indentation.
Good formatting is not a pointless chore, it's an essential tool to help yourself understand what you already wrote.
Have you tried using the bukkit scheduler? People tend to forget that bukkit's API can handle countdowns very well. Just call the scheduler with this
myInteger = Bukkit's.getScheduler.scheduleSyncRepeatingTask(plugin, new runnable(), 0L, 20L)
Put your JavaPlugin extension class in as plugin, use runnable adding unimplemented methods, 0L is ticks before first run, 20L is ticks between each run.
Cancel the countdown like this
Bukkit's.getScheduler.cancelTask(myInteger)
I a writing a program using RobotC for the Lego NXT to imitate the behaviour of a puppy. This section of code is supposed to rotate the head which is connected to motor port 3 and read the value on the ultra sonic sensor. If while the head is turned, the dog is called, it will turn in the direction it was already facing. The following function is called when the ultrasonic sensor reads a value (meaning the robot has come close to a wall):
visible
void SonarSensor()
{
int sensorValleft;
int sensorValright;
bool alreadyTurned = false;
int i,j;
i = 0;
j = 0;
motor[1] = 0;
motor[2] = 0;
motor[3] = -SPEED/2;
wait10Msec(15);
motor[3] = 0;
sensorValleft = SensorValue[3];
while(i<100)
{
if(SensorValue[4] > 40)//calibrate sound sensor
{
//turn left
motor[1]=SPEED;
motor[2] = -SPEED;
wait10Msec(25);
i = 1000;
j = 1000;
alreadyTurned = true;
}
else
{
i++;
wait1Msec(5);
}
}
motor[3] = SPEED/2;
wait10Msec(30);
motor[3] = 0;
sensorValright = SensorValue[3];
while(j<100)
{
if(SensorValue[3] > 1)//calibrate sound sensor
{
//turn right
motor[1]-=SPEED;
motor[2] = SPEED;
wait10Msec(25);
j = 1000;
alreadyTurned = true;
}
else
{
j++;
wait1Msec(5);
}
}
if(alreadyTurned == false)
{
if(sensorValleft > sensorValright)
{
//turn left
motor[1]=SPEED;
motor[2] = -SPEED;
wait10Msec(25);
}
else
{
//turn right
motor[1]=-SPEED;
motor[2] = SPEED;
wait10Msec(25);
}
}
}visible
When the head (motor[3]) rotates the first time the error 0002EA Type2 appears on the NXT screen. At first we thought it was because we were over-rotating the motor causing it to be obstructed so we tried to play around with the wait times but it made no difference.
Any ideas on what causes this error or how to fix it would be appreciated.
Thanks,
Dominique
The answer as to why only motor[3] causes an error is actually quite simple. The motorA, motorB, and motorC values are defined in an enum, where motorA=0, motorB=1, and motorC=2. So, motor[1] and motor[2] are equivalent to calling motor[motorB] and motor[motorC]. However, motor[3] isn't equivalent to anything. It's trying to set the power of a motor that doesn't exist. motor[0] would be ok, however, and would correspond to motor[motorA].
While debugging, I started putting break points in to see where the error was and it alwas occurred on the line motor[3] = -SPEED/2; it turns out that with the third motor the proper syntax is to use motor[motorA]=-SPEED/2;. I am not sure why only this motor returns this error as I am using two other motors which I set new speeds using
motor[1]=SPEED;
motor[2]=SPEED;
However, this was the way to abolish the error.
Im needing to use local variables but when i use them for a timer (decreases time until conditions are met) it doesnt work
for (int i = 0; i < Weapons.Count; i++)
{
if (Weapons[i].ItemType == 6)
{
if (standard.IsKeyDown(Keys.G))
{
Cannons.Add(new CannonFire(this));
}
}
else if (Weapons[i].ItemType == 7)
{
float Recharge = Weapons[i].Laser.Rate;
Recharge -= (float)gametime.ElapsedGameTime.Seconds;
if (standard.IsKeyDown(Keys.G) && Recharge < 0)
{
laser.Add(new LaserFire(this, new Vector3(Weapons[i].Laser.range, 1, 1) ));
Recharge = Weapons[i].Laser.Rate;
}
}
}
other relevant code is where im getting the rate from
public class LaserItem
{
float Damage;
float Range;
float Last;
float RechargeRate;
public float damage
{
get { return Damage; }
set { Damage = value; }
}
public float Rate
{
get { return RechargeRate; }
set { RechargeRate = value; }
}
public float Life
{
get { return Last; }
set { Last = value; }
}
it works without the timer but i cant have it like that because i dont want 300 lasers to be built every time someone hits the key. as far as i can tell the timer is set to the laser rate every frame so it never reaches 0 (this section it in the update function)
for this piece of code its fine but when i need it in a loop i have to use local variables;
From what I can understand, what you are doing in the code is that you're creating a new local variable with the value set to the recharge rate of the laser every single update, firing it when the time from the last update is longer than the recharge rate - this would occur only on a very slow update.
Taking into account the automatic Update (the main loop one) calling of XNA, what would help you is setting some class variable for the Weapon, e.g. RemainingRecharge and when you fire, set it to the recharge rate and substract the elapsed time every update until it reaches zero or less. The only difference from your code is that the recharge is moved to the class instance and thus preserved between updates.
Recharge isn't a reference or a pointer; it's a copy (as float and double are immutable types). So, assigning a value to Recharge at the end of the if() block does absolutely nothing. (I'd bet that it even gets removed by the compiler).
Try this:
else if (Weapons[i].ItemType == 7)
{
float recharge = Weapons[i].Laser.Rate;
recharge -= (float)gametime.ElapsedGameTime.Seconds;
if (standard.IsKeyDown(Keys.G) && recharge < 0)
{
laser.Add(new LaserFire(this, new Vector3(Weapons[i].Laser.range, 1,1)));
/// changed the the next line:
Weapons[i].Laster.Rate = recharge;
}
}
i figured it out, XNA has a TimeSpan thing you can use its easier to work with and you can tell it if it reaches a number reset and do what you want
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.