This should be easy but I may be misunderstanding something fundamental.
I have ellipses (called movers) on a screen in box2d. The ellipse is represented by a body. The body has a variable r which I use to make the ellipse size.
I want to destroy the ellipse when the r=0.
This is what i have written:
for (int i = 0; i < movers.length; i++) {
if(movers[i].r<0){
box2d.destroyBody(movers[i].body);
}
}
However this gives me an assertion error at the line box2d.destroyBody(movers[i].body);
How do I correct this? Is this because I am destroying the body but not the ellipse possibly or some other subtlety?
So the answer is not intuituitive but for future reference the problem is that box2d gets confused when trying to kill bodies if it is done inside of a world timestep.
What does this mean?
It means that you have to add all the bodies you are using to an arrayList rather than an array and your code should work from that. If you do that then at the end of void draw you can add the following (where movers is an arrayList of objects which have bodies and r is an attribute which defines whether a body should be destroyed or not):
for (int i = movers.size()-1; i >= 0; i--) {
Mover p = movers.get(i);
if (p.r<0) { //r is whatever attribute of your body
movers.remove(i);
}
}
This will destroy the bodies by removing them from the arrayList you are working from
Related
Hellooooo, hope y'all are doing great.
A while ago, I asked a question about how to do particle explosions in AS3 when I was coming from AS2. Luckily, I got help from Organis (thank you so much btw), but every time I try export the animation in SWF, it keeps crashing my file and I'm not sure why?
I should probably preface that what I'm doing is specifically for animation. I'm not trying to make a game, just a simple script where the movieclip I created can explode into different objects in its timeline...if that made any sense.
In case anyone needs the actual file itself, you can download it right here: https://sta.sh/018lqswjfmp2
Here is the AS2 version in case anyone needs it: https://sta.sh/02fzsqon3ohw
Here is the code given to me by Organis:
// Allows the script to interact with the Particle class.
import Particle;
// Number of particles.
var maxparticles:int = 200;
// I imagine you will need to access the particles somehow
// in order to manipulate them, you'd better put them into
// an Array to do so rather then address them by their names.
var Plist:Array = new Array;
// Counter, for "while" loop.
var i:int = 0;
// The loop.
while (i < maxparticles)
{
// Let's create a new particle.
// That's how it is done in AS3.
var P:Particle = new Particle;
// The unique name for the new particle. Whatever you want it for.
P.name = "particle" + i;
// Enlist the newly created particle.
Plist.push(P);
// At the moment, the P exists but is not yet attached to the display list
// (or to anything). It's a new concept, there wasn't such thing in AS2.
// Let's make it a part of the display list so that we can see it.
addChild(P);
i++;
}
And in case anyone needs it, here is the code I used for AS2:
maxparticles = 200; //number of particles
i = 0; //counter, for "while" loop
while(i < maxparticles){
newparticlename = "particle" + i; //creates a new name for a new particle instance
particle.duplicateMovieClip(newparticlename, i); //duplicates our particle mc
i++;
}
I'm an Italian student and I'm new in programming. I need your help for a school project.
I'm making a blob tracking program using Daniel Shiffman's tutorials. Currently I have 2 blobs on the screen. I am identifying them with 2 IDs: number 0 and number 1.
I need to put some conditions on those blobs: if one blob is in a certain part of the screen and the other one is in another part, I need to call a function.
I don't know how to put the if conditions separately for the two ids. Below is some pseudo code of what I would like to achieve:
for (id==0)
if (...) and
for (id==1)
if(...) then {
void()
}
I would really appreciate any help!
I don't really know where you want the blobs to be when the desired function fires, but I can try to give you an example...
Blob
Assign some sort of position variable, in this case PVector, to your blob object.
class Blob {
PVector position;
Blob (PVector position) {
this.position = position;
}
void update() {
*random movements, etc...*
}
}
Create two blob objects
Create two objects and assign a position to each of them.
Blob[] blobs = new Blob[2];
void setup() {
size(400, 400);
blobs[0] = new Blob(5, new PVector(40, 40));
blobs[1] = new Blob(13, new PVector(100, 100));
}
Check if blobs is at left or right side of the screen
I check if blob[0] is at the left side of the screen and if blob[1] is at right side of the screen. If they are, at the same time, the desiredFunction(); will fire.
void draw() {
for (int i = 0; i < blobs.length; i++) {
blobs.update();
}
if (blobs[0].position.x < (width / 2) && blobs[1].position.x < (width / 2) {
desiredFunction();
}
}
Remember
This is just an example. You could of course check other parts of the screen instead of the left and right parts. You can also use IDs on your blobs instead of an array, I just thought it was better to just use an array in this case.
PS: I wrote this answer without having processing started. The code has certainly a couple of typing errors.
For the example you have described, you can achieve this using the && operator in one if statement.
First assign the conditions you want to test to boolean variables. For example, create the boolean variables id0IsThere, and id1IsThere, and set them to true if the blobs are in the locations you want them to be in. Then use the following if statement:
if (id0IsThere && id1IsThere) {
yourFunction();
}
The && operator means that the code inside the if statement that executes yourFunction() is only executed if both conditions are true. In this case, if both blobs are in the positions you want them to be in. Hope that helps. Read more about if statements and the && operator here:
https://processing.org/reference/if.html
https://processing.org/reference/logicalAND.html
I want to clone objects in quite a complex hierarchy and give each a unique xyz to assemble an even more complex hierarchy. It would be simpler to clone the last clone instance rather than pick out the originally cloned object. Recursion is handled by separate Javascript. Any foreseeable problems here?
No problem, matrices. Pseudo-code
<code>
srcRootObj.updateMatrixWorld(true);
for(var i = 0; i < srcRootObj.childrens.lenght; i++)
{
var obj = srcRootObj.childrens[i];
var m = obj.matrixWorld.clone(); // or matrix
m.applyYouTransform();
//dst[i].applyMatrix(m); // this d`t correct
dst[i].matrix.copy(m);
// & add recursive if needed
}
</code>
Simply. Why does not approach?
I'm studying Java so I'm pretty new.
I'm creating a simple 'maze' type game using GUI layouts, images, labels ect..
To create my maze layouts I used an array of strings;
mazeLayout[0] = "WWWWWWWWWW";
mazeLayout[1] = "WSSSWWSWWW";
mazeLayout[2] = "WSWSWWSSSW";
mazeLayout[3] = "WSWSWWWWSW";
mazeLayout[4] = "WSWSWWWWSW";
mazeLayout[5] = "WSWSWSSSSW";
mazeLayout[6] = "WSWSWSWWWW";
mazeLayout[7] = "WSWSWSWWWW";
mazeLayout[8] = "WSWSSSWWWW";
mazeLayout[9] = "WWWWWWWWWW";
and then converted this into a 2d array and placed a label with in image icon in it depending on the string being 'W' for wall or 'S' for space. Also the labels are an array, my thoughts behind this was for restricting movement of the player so they can't walk though walls.
int mw = 0;
int mf = 0;
for(int y = 0; y < 10; y++){
for(int x = 0; x < 10; x++){
mazeLayout2d[y][x] = mazeLayout[y].substring(x, x+1);
if (mazeLayout2d[y][x].equals("W")){
lblmazewall[mw] = new JLabel();
mazewall = new ImageIcon("mazewall.png");
lblmazewall[mw].setIcon(mazewall);
pCenter.add(lblmazewall[mw]);
mw++;
pCenter.revalidate();
}
if (mazeLayout2d[y][x].equals("S")){
lblmazefloor[mf] = new JLabel();
mazefloor = new ImageIcon("mazefloor.png");
lblmazefloor[mf].setIcon(mazefloor);
pCenter.add(lblmazefloor[mf]);
mf++;
pCenter.revalidate();
}
}
}
My problem is when i run this line
System.out.println(lblmazewall[x].getLocation()); //x being any number
I always get java.awt.Point[x=0,y=0]
I would like to know how to get the location of each wall label so i can check it against my player movement.
Is this even a valid way to do something like this?
Could someone teach me a more efficient way?
Sorry for my crude snippets and or bad programming
Thankyou Niall.
public Point getLocation()
Due to the asynchronous nature of native event handling, this method can return outdated values (for instance, after several calls of setLocation() in rapid succession). For this reason, the recommended method of obtaining a component's position is within java.awt.event.ComponentListener.componentMoved(), which is called after the operating system has finished moving the component.
The layout might not have used setLocation() internally. So that getLocation() does not return the value as expected.
I am having trouble calling EMD() in OpenCV 2.4.2 under Mac OS ML.
I have a class with an attribute Mat _signature defined like that :
Mat _signature(size,dim+1,CV_32F);
for (int i = 0; i<size; ++i){
_signature.at<float>(i,0) = weight;
for (int j = 1; j < dim+1; ++j){
_signature.at<float>(i,j) = vec[i].at<float>(0,j-1); // vec[i] is a line vector containing the position in R^dim
}
}
I then have u and v 2 instances of that class, and when I call EMD(u._signature, v._signature, CV_DIST_L2);
It fails with OpenCV Error: One of arguments' values is out of range () in icvInitEMD, file /*SOME PATH*/OpenCV-2.4.2/modules/imgproc/src/emd.cpp, line 408
I looked at the sourcecode but could not figure out what this fails. My arguments appear in correspondence to what the documentation wants. Any help will be appreciated.
Ok, it took me quite some time to figure it out, but among my data there was a component of one of my vector which was miscalculated, and ended up being NaN.
Of course this was buried deep into my data so that it would be completely lost in any amount of data reasonably observable via a debugger (or even cout)
The cryptic error from OpenCV did the rest in confusing me.
For people stumbling upon the same issue as me :
Make sure your weight vectors are not zero
Make sure none of your data is NaN