Collision without physics

Zoff · October 12, 2010, 5:28pm

Hy,

sorry I come back on the subject because i didn t found yet the way to do it

I would like for exemple to listen the collision of 3 spheres (a,b & c)

when the touch each other i would like to know, “a” touch “b”, or “b” touch “c” etc…

CollisionResult ?

Sorry for being slow on this subject !

Zoff

Zoff · October 12, 2010, 7:20pm

like how to know with this code, who’s touching who…

[java]package jme3test.helloworld;

import com.jme3.app.SimpleApplication;

import com.jme3.material.Material;

import com.jme3.math.ColorRGBA;

import com.jme3.math.FastMath;

import com.jme3.math.Vector3f;

import com.jme3.scene.Geometry;

import com.jme3.scene.shape.Sphere;

public class ThreeBallsCollision extends SimpleApplication{

private Geometry a, b, c;

private int cpt = 0;

public static void main(String[] args){

ThreeBallsCollision app = new ThreeBallsCollision();

//app.setShowSettings(false);

app.start();

}

public void simpleInitApp() {

cam.setLocation(new Vector3f(0,-20,0));

cam.lookAt(Vector3f.ZERO, new Vector3f(0, 1,0));

Sphere sphereA = new Sphere(32, 32, 1);

a = new Geometry(“sphere A (blue)”, sphereA);

Material matA = new Material(assetManager, “Common/MatDefs/Misc/WireColor.j3md”);

matA.setColor(“m_Color”, ColorRGBA.Blue);

a.setMaterial(matA);

rootNode.attachChild(a);

Sphere sphereB = new Sphere(32, 32, 1);

b = new Geometry(“sphere B (red)”, sphereB);

Material matB = new Material(assetManager, “Common/MatDefs/Misc/WireColor.j3md”);

matB.setColor(“m_Color”, ColorRGBA.Red);

b.setMaterial(matB);

rootNode.attachChild(b);

Sphere sphereC = new Sphere(32, 32, 1);

c = new Geometry(“sphere C (green)”, sphereC);

Material matC = new Material(assetManager, “Common/MatDefs/Misc/WireColor.j3md”);

matC.setColor(“m_Color”, ColorRGBA.Green);

c.setMaterial(matC);

rootNode.attachChild©;

}

public void simpleUpdate(float tpf) {

a.setLocalTranslation(5FastMath.cos(cpt/1000.0f), 0, 0);

b.setLocalTranslation(0, 0, 5FastMath.cos(cpt/1000.0f));

c.setLocalTranslation(5FastMath.cos(cpt/500.0f), 0, 5FastMath.sin(cpt/500.0f));

rootNode.updateGeometricState();

cpt++;

}

}[/java]

Zoff · October 12, 2010, 8:48pm

I tried something… but i got an exeption

here is the code :

[java]package jme3test.helloworld;

import com.jme3.app.SimpleApplication;

import com.jme3.bounding.BoundingSphere;

import com.jme3.collision.CollisionResults;

import com.jme3.font.BitmapText;

import com.jme3.material.Material;

import com.jme3.math.ColorRGBA;

import com.jme3.math.FastMath;

import com.jme3.math.Ray;

import com.jme3.math.Vector3f;

import com.jme3.scene.Geometry;

import com.jme3.scene.Node;

import com.jme3.scene.Spatial;

import com.jme3.scene.shape.Sphere;

public class ThreeBallsCollision extends SimpleApplication{

private Spatial a, b, c;

private int cpt = 0;

public static void main(String[] args){

ThreeBallsCollision app = new ThreeBallsCollision();

//app.setShowSettings(false);

app.start();

}

public void simpleInitApp() {

cam.setLocation(new Vector3f(0,-20,0));

cam.lookAt(Vector3f.ZERO, new Vector3f(0, 1,0));

Sphere sphereA = new Sphere(32, 32, 1);

a = new Geometry(“sphere A (blue)”, sphereA);

Material matA = new Material(assetManager, “Common/MatDefs/Misc/WireColor.j3md”);

matA.setColor(“m_Color”, ColorRGBA.Blue);

a.setMaterial(matA);

//rootNode.attachChild(a);

Sphere sphereB = new Sphere(32, 32, 1);

b = new Geometry(“sphere B (red)”, sphereB);

Material matB = new Material(assetManager, “Common/MatDefs/Misc/WireColor.j3md”);

matB.setColor(“m_Color”, ColorRGBA.Red);

b.setMaterial(matB);

//rootNode.attachChild(b);

Sphere sphereC = new Sphere(32, 32, 1);

c = new Geometry(“sphere C (green)”, sphereC);

Material matC = new Material(assetManager, “Common/MatDefs/Misc/WireColor.j3md”);

matC.setColor(“m_Color”, ColorRGBA.Green);

c.setMaterial(matC);

//rootNode.attachChild©;

shootables = new Node(“Shootables”);

rootNode.attachChild(shootables);

shootables.attachChild(a);

shootables.attachChild(b);

shootables.attachChild©;

}

Node shootables;

public void simpleUpdate(float tpf) {

a.setLocalTranslation(5FastMath.cos(cpt/1000.0f), 0, 0);

b.setLocalTranslation(0, 0, 5FastMath.cos(cpt/1000.0f));

c.setLocalTranslation(5FastMath.cos(cpt/500.0f), 0, 5FastMath.sin(cpt/500.0f));

rootNode.updateGeometricState();

CollisionResults results = new CollisionResults();

a.collideWith(b, results);

a.collideWith(c, results);

b.collideWith(c, results);

if (results.size()!=0){

System.out.println("

Collisions? " + results.size() + "

");
}

cpt++;
}
}
[/java]

here is the console error

Oct 12, 2010 4:44:24 PM com.jme3.app.Application handleError
SEVERE: Uncaught exception thrown in Thread[LWJGL Renderer Thread,5,main]
com.jme3.collision.UnsupportedCollisionException
at com.jme3.collision.bih.BIHTree.collideWith(BIHTree.java:479)
at com.jme3.scene.Mesh.collideWith(Mesh.java:478)
at com.jme3.scene.Geometry.collideWith(Geometry.java:232)
at jme3test.helloworld.ThreeBallsCollision.simpleUpdate(ThreeBallsCollision.java:79)
at com.jme3.app.SimpleApplication.update(SimpleApplication.java:209)
at com.jme3.system.lwjgl.LwjglAbstractDisplay.runLoop(LwjglAbstractDisplay.java:144)
at com.jme3.system.lwjgl.LwjglDisplay.runLoop(LwjglDisplay.java:133)
at com.jme3.system.lwjgl.LwjglAbstractDisplay.run(LwjglAbstractDisplay.java:198)
at java.lang.Thread.run(Thread.java:619)

Zoff · October 12, 2010, 8:49pm

The error in my file is notge at the line 79 but 69 (i removed some coments at the last post)

a.collideWith(b, results);

Zoff · October 12, 2010, 11:47pm

i posted an exemple of the same kind of test, but with physics http://hub.jmonkeyengine.org/groups/contribution-depot-jme3/forum/topic/exemple-of-collision-detection-with-ghost-wphysics/

I still do not know how to do without them

matnicgri · January 29, 2012, 10:12pm

This example uses the class is in jme3, for I have seen several classes that can not be used anymore? I have such CollideWIth accesiblesolo the method. Long ago I’m trying to capture the collision of two cubes of type geometry but I fail, I get the same exception you mention.

The section of code is something like this:

private void createPlayer(){

Box b = new Box(new Vector3f(0f,0f,0f), 1, 1, 1);

player = new Geometry(“Player”, b);

Material mat = new Material(assetManager, “Common/MatDefs/Misc/Unshaded.j3md”);

//mat.setColor(“Color”, ColorRGBA.Blue);

mat.setTexture(“ColorMap”, assetManager.loadTexture(“Blender/2.4x/WoodCrate_lighter - Height Map.png”));

//mat.setTexture(“ColorMap”, assetManager.loadTexture(“Textures/ColoredTex/Monkey.png”));

player.setMaterial(mat);

rootNode.attachChild(player);

}

private void createBox(){

Box b1 = new Box(new Vector3f(1f,1f,0f), 1, 1, 1);

box = new Geometry(“Box”, b1);

Material mat1 = new Material(assetManager, “Common/MatDefs/Misc/Unshaded.j3md”);

//mat.setColor(“Color”, ColorRGBA.Blue);

mat1.setTexture(“ColorMap”, assetManager.loadTexture(“Blender/2.4x/WoodCrate_lighter.png”));

box.setMaterial(mat1);

rootNode.attachChild(box);

}

CollisionResults cr=new CollisionResults();

player.collideWith(box, cr);

System.out.println(cr.size());

WASD · January 30, 2012, 9:11am

If it’s spheres you can simply check their distance to each other. If a two spheres are 1 meter in diameter each and their centers are closer than 1 meter then they are touching.