We Keep Coding

LibGDX — How to detect if 3d object was clicked on?

I'm trying to make a simple bit of code that will detect whether a model was clicked on. So far the best method I've seen is to create some sort of rectangle around the mesh and detect with Gdx.input.justTouched() to get the x,y coordinates, and then check if the rectangle contains the coordinates returned by justTouched().
I have no idea if there's a better way to do this, some kind of mesh onClick listener or something that LibGDX has in place that I'm unaware of (I've been scouring Google and the javadocs but I can't seem to find anything). I don't really need to deal with the z-axis coordinate, at least I don't think so. I only have the one PerspectiveCamera and it's not going to be moving around that much (not sure if this matters?)
Anyways, in my render() method I have:
if (Gdx.input.justTouched()) {
//this returns the correct values relative to the screen size
Vector2 pos = new Vector2(Gdx.input.getX(), Gdx.input.getY());
//I'm not sure how to get the correct rectangle to see what the
//width and height are for the model relative to the screen?
Rectangle modelBounds = new Rectangle(<<not sure what to put here>>);
if (modelBounds.contains(pos.x, pos.y) {
System.out.println("Model is being touched at: " + pos.x + ", " + pos.y);
}
}
I'm really not sure if this is the correct way to do this. I can get the position of the model with:
modelInstance.getNode("Node1").globalTransform.getTranslation(new Vector3());
but I'm not sure how to get the width and height as a rectangle relative to the screen size, if it's even possible.
I'm also unsure if this would cause massive lag, as I'm going to have about 7 nodes total that I need to detect if they're clicked on or not.
Is there a better way to do this? If not, is there a way to get the model width & height relative to the screensize (or camera, maybe)?
EDIT: Read about using Bounding Boxes, seems like what I need. Not quite sure how to implement it properly, however. I've changed my code to such:
public ModelInstance modelInstance;
public BoundingBox modelBounds;
#Override
public void create() {
...
//omitted irrelevant bits of code
modelInstance = new ModelInstance(heatExchangerModel);
modelBounds = modelInstance.calculateBoundingBox(new BoundingBox());
}
#Override
public void render() {
...
if (Gdx.input.justTouched()) {
Vector3 pos = new Vector3(Gdx.input.getX(), Gdx.input.getY(), 0);
System.out.println(pos);
if (modelBounds.contains(pos)) {
System.out.println("Touching the model");
}
}
}
I'm not really sure what the output of BoundingBox is supposed to be, or how the numbers it gives me correlates to the position in a 2d space. Hmm..
EDIT2: Think I'm getting closer.. Read about Rays and the .getPickRay method for my PerspectiveCamera. .getPickRay seems to return completely unusable numbers though, like really tiny numbers. I think I need to do something like:
if (Gdx.input.justTouched()) {
Vector3 intersection = new Vector3();
Ray pickRay = perspectiveCamera.getPickRay(Gdx.input.getX(), Gdx.input.getY());
Intersector.intersectRayBounds(pickRay, modelBounds, intersection);
}
and then intersection should give me the point where they overlap. It appears to be not working, however, giving me really small numbers like (4.8066642E-5, 2.9180354E-5, 1.0) .. hmmm..

How do I draw an interactive Graph/Lines in Java?

Solved.
I had a question before but it was very badly posted so here it goes again, according to better rules.
I want to create some style of a graph such as this image:
.
It's based on a physics law, Snell's Law. As of now I've managed to paint the graph it self with a basic Line2D.Double which you can see here (Line.java). Then all I need to do is, in the interface class, add the lines to the array in that class as so:
LinesArray.addLine(150 , 25 , 150 , 275);
And every time it adds a new one, it repaints as you can see in the code sample.
But the problem is that I have no idea how to make this interactive. I wanted to make it interactive, as in that you could actually move those lines and at the same time you move the first line, the second would move accordingly to the Snell's Law formula, which is:
n1 * sin( a1 ) = n2 * sin ( a2 )
Considering that a1 is the first (left) angle, and a2 the second (right) angle in the first image posted.
A perfect example of what I'd hope to achieve is this one.
And if interactive movement is too hard (I'm on a 2 days schedule), this example is also a possibility.
Correct me if I'm wrong but for the second one, all that I'd need to do is calculate the mouse's coordinates and draw and calculate everything from there.
Here (menu_ui.java) is my interface class, in which the method I'm currently working with the lines is "menuSnell()" and here (Snell.java is my Snell class which contains the logic. Apologies for portuguese comments but it's fairly simple code which you don't really need comments to understand, plus I've separated it into readable methods.
So basically, my question is how do I make those lines interactive in the way I've described above.
Thanks!

I am not a graphic expert, but I had similar work a long time ago. I had an object that I need to repaint. I created my own JPanel, which holds my objects that should be paint. Whenever something changed, I call repaint method on JPanel. It looked like this
http://sourceforge.net/p/scribbler-cvut/code/132/tree/Tuzka/src/cz/cvut/scribbler/panel/RewritableGlassPane.java.
private LinkedList<ColoredArea> background = new LinkedList<ColoredArea>();
/**
* Vykreslí všechny položky v senamu vykreslených obrazců
* #param g2d grafika k vykreslení
*/
public void paintShape(Graphics2D g2d) {
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
for (ColoredArea area : background) {
area.fill(g2d);
}
if (mouse != null && !block) {
g2d.setColor(mouse_color);
g2d.draw(mouse);
}
if (point!=null){
SetPointsDialog.paintPoints(point, maxPoint, parent.getChildsSize(), g2d);
}
}
#Override
public void paint(Graphics g) {
paintShape((Graphics2D) g);
}
#Override
protected void paintComponent(Graphics g) {
paintShape((Graphics2D) g);
}
Everything I need to paint was stored in background variable. When something I LinkedList changed, I invoke repaint () method on the window.
I have a full source code store here: http://sourceforge.net/projects/scribbler-cvut/ but it was my long term project, so it is a little bit big.

Slick2d, How can i draw a string on screen for a few seconds?

I've been trying to figure this out, all I want to do is be able to draw a string for longer than just a frame, but when I call it in the method I want it to flash up then disappear immediately, any advice would be appreciated :) I'm using something like this:
g.drawString("You got a Key!", 100, 100);
I'm doing this in a method which is called after an Item is picked up
public void addItemFound(Graphics g){
ip.mainInventory[ip.getFirstEmptyStack()] = getItemStackFound();
System.out.println(this.getItemFound() + " added");
g.drawString("You Got a Key!", 100, 100);
}
That's the full method if you were interested :) Thanks!Also apologies for the dumb question, i'm a newbie to this :P

I believe that the best way to do this project would be to draw the scene at regular intervals e.g. 10 milliseconds using a Thread.sleep(). This way, you can simply add a variable to show the message for, say, 100 loops (1 second) like this:
private LinkedList<String> drawStringList= new LinkedList<>();
private LinkedList<Integer> drawStringTimeout= new LinkedList<>();
private LinkedList<Integer[]> drawStringPos= new LinkedList<>();
public void addText(String stringToWrite, int posX, int posY, int timeOut) {
drawStringList.add(stringToWrite);
int[] pos = new int[2];
pos[0] = posX;
pos[1] = posY;
drawStringPos.add(pos);
drawStringTimeout.add(timeOut);
}
private void mainLoop() {
...items to be drawn here...
for(int i=0;i<drawStringList.size();i++){
g.drawString(drawStringList.get(i),drawStringPos.get(i)[0],drawStringPos.get(i)[1]);
drawStringTimeout.set(i,drawStringTimeout.get(i)-1);
if(drawStringTimeout.get(i)<=0) {
drawStringList.remove(i);
drawStringTimeout.remove(i);
drawStringPos.remove(i);
}
}
try { Thread.sleep(10); } catch (Exception e) {}
}
In this code, you must add the string you want to draw to drawStringList, add the number of loops you want it to stay for to drawStringTimeout and add the position you would like to draw it in to drawStringPos as an array (you could use a point if you wanted to). I have made a method to do this.

I don't know what Dan300 is trying to tell you to do but that's way, way, way over complicated. Slick2D works on gamestates:
http://slick.ninjacave.com/javadoc/org/newdawn/slick/state/GameState.html
The gamestate has a method called render(). The render() is called every single cycle of the loop to update your screen with drawing information. If you want to draw the text on the screen for a longer time you should be drawing the text somewhere within the stack space of this render() function.
What is happening now is you have a function with one specific purpose that only exists every so briefly: add an item to the player. The game comes across this statement and when adding an item within that 1 cycle the text will be drawn. But the next cycle when the player isn't picking up an item it won't come by that drawString statement and you won't have your string on your screen longer than 1 game cycle.

Java Application : mouseDragged Event isn't Executed Often Enough

Is there a way to make the mouseDragged Event be called more Often ( In my Case, Drawing a Color? I need it for Smooth Drawing, because right now, if you move too fast, it doesn't Draw All my Path. Also, I have an 2D Array Storing the Color of the Pixel, so that's also Problematic if I try to solve by problem by another Way, that's why I thought Increasing the mouseDragged Frequency would be the Best thing to Do
Thanks

If you want smooth drawing, you'd likely have to interpolate the data yourself. If you get an event at (3,3) and another at (10,10) you can figure the slope between the two, and iterate through the logical points that the mouse must have been dragged to get from (3,3) to (10,10)
I don't know of a way to force mouseDragged to update faster, and if, for instance the system was under high load, or someone used a touch screen, you might get huge jumps anyhow.

If you are drawing ovals to as color lines, change to lines:
ArrayList<> colors;
mousepressed(Event e) {
startPoint = e.getPoint();
}
mousedragged(Event e) {
colors.add(new Color(startPoint, e.getPoint);
startPoint = e.getPoint();
}
class Color() {
Color(Point start, Point end) {
// ...
}
paint(Graphics g) {
g.drawLine(start, end);
}
}

Sprite Animation Management Using Threads

I'm in the process of creating my own two-dimensional game. Every object in the game world has a Sprite object, and when the screen is drawn, the object's sprite is drawn in the object's location.
The sprite class can be either a single image or a series of images used to make an animates sprite.
import java.awt.image.BufferedImage;
import java.awt.Graphics2D;
public class Sprite implements Runnable{
private int currentImage;
private BufferedImage[] sprites;
private int delayMS;
private Thread animation;
public Sprite(BufferedImage sprite){
sprites = new BufferedImage[1];
sprites[0] = sprite;
}
public Sprite(BufferedImage[] spriteAnimation,int delay){
this.sprites = spriteAnimation;
currentImage = 0;
delayMS = delay;
//start a thread to time animation
animation = new Thread(this);
animation.start();
}
private void next(){
if(currentImage < sprites.length - 1)
currentImage++;
else
currentImage = 0;
}
public void run() {
while (Thread.currentThread() == animation) {
//delay the animation for delayMS
try {
Thread.sleep(delayMS);
} catch (InterruptedException e) {
break;
}
//next image
next();
}
}
public void draw(Graphics2D g,int x,int y){
g.drawImage(sprites[currentImage],null,x,y);
}
}
I couldn't find any reliable information on the subject of using threads to run many animations, and I was wondering whether this was the best approach.
Everything works great until I throw 200ish identical objects into the world. FPS begins to lower and some animated sprites begin to change frames at different times. This would make sense since the threads would start to delay when instantiated.
My questions is whether there is a more efficient way to handle this, allowing me to use more objects without significant FPS loss, and synchronize the thread/threads so that the animations switch frames together.

The usual way of doing this is to have a game loop that knows all the sprites and calls a draw method on them (or preferably only those that needs be redrawn) for each frame. This way, whenever a sprite decides it wants to animate, it will not do so until the next frame. Just do the animating the the draw method, e.i. the next() part.
And of course, in the game loop you put your delay, which will determine the fps.
To get frame rate independent animation you do the same but add an argument to the draw method which says how much time has passed since the last draw, then calculate the amount of animation based on this.

Instead of running every sprite on its own thread, you could put the sprites on a container, and on a rendering thread iterate through all visible sprites and draw them (you could even implement sprite priorities, render background layers before sprites, ...).

if you use more threads for sprites (i.e, one thread for one sprite) then it will eat your cpu and it will hang the best way to implement animation in games is for every run loop of thread do change the animation sequences ( like next image or previous upon key Presses) and paint the sprites at the end.
Here if it is more sprites and paint will take more time then FPS will drop at the time two or three threads max with synchronization