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Added convenience method worldToLocal(Quaternion) to spatial. #2559

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Added convenience method worldToLocal(Quaternion) to spatial. #2559

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234545d
Added `worldToLocal` method to `Spatial` for quaternion transformatio…
zzuegg Sep 19, 2025
3a43016
Fixed `worldToLocal` method to correctly handle store parameter for q…
zzuegg Sep 19, 2025
baae9df
Replaced `Assert.assertEquals` with `isSimilar` in `SpatialTest` for …
zzuegg Sep 20, 2025
aae6052
removed the need to allocate a temporary object.
zzuegg Sep 20, 2025
3048352
Formatted multiline method call in `Spatial` for improved readability.
zzuegg Sep 20, 2025
726ea52
Formatted multiline method call in `Spatial` for improved readability.
zzuegg Sep 20, 2025
2eb11cf
Refactored `worldToLocal` in `Spatial` to utilize `TempVars` for opti…
zzuegg Sep 23, 2025
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32 changes: 32 additions & 0 deletions jme3-core/src/main/java/com/jme3/scene/Spatial.java
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Original file line number Diff line number Diff line change
Expand Up @@ -986,6 +986,38 @@ public Vector3f worldToLocal(final Vector3f in, final Vector3f store) {
return worldTransform.transformInverseVector(in, store);
}

/**
* Transforms the given quaternion from world space to local space relative to this object's transform.
*
* @param in the input quaternion in world space that needs to be transformed
* @param store an optional Quaternion to store the result; if null, a new Quaternion will be created
* @return the transformed quaternion in local space, either stored in the provided Quaternion or a new one
*/
public Quaternion worldToLocal(final Quaternion in, Quaternion store){
checkDoTransformUpdate();
if(store == null){
store=new Quaternion(in);
}else{
store.set(in);
}
Quaternion rotation = worldTransform.getRotation();
//can we be sure if the quaternion is normalized?
//if yes, the conjugate could be used, and the normalizing procedure skipped
//store.multLocal(-rotation.getX(), -rotation.getY(), -rotation.getZ(), rotation.getW();

//Second option is to normalize manually
float norm = rotation.norm();
store.multLocal(rotation.getX()*-norm, rotation.getY()*-norm,
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This doesn't look right to me if you're trying to normalize and invert the rotation. From looking at Quaternion, it seems like norm should be changed like this:

norm = FastMath.invSqrt(norm) / norm;

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Generally i agree, using jme math i have not yet managed to create a non normalized quaternion.

        for (int i = 0; i < 1000000; i++) {
            Quaternion quaternion=new Quaternion().fromAngles(FastMath.nextRandomFloat()*-360,FastMath.nextRandomFloat()*360,FastMath.nextRandomFloat()*360);
            Quaternion inverse = quaternion.inverse();
            float norm = quaternion.norm();
            //norm = FastMath.invSqrt(norm)/norm;
            System.out.println(norm);
            quaternion.set(quaternion.getX()*-norm, quaternion.getY()*-norm, quaternion.getZ()*-norm, quaternion.getW()*norm);
            if(!quaternion.isSimilar(inverse,0.000001f)){
                System.out.println("Fail");
                System.out.println(quaternion);
                System.out.println(inverse);
                System.exit(1);
            }
        }

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I could use temp vars and use the existing math functions. I probably prefer that. Considering that this code is probably never executed in the "hot loop"

rotation.getZ()*-norm, rotation.getW()*norm);
return store;

//Third option is to temporarily change the parent's quaternion. More expensive then option 2,
//but produces more accurate results. compared to option 2. (Error still below 1e-6f)
//store.multLocal(rotation.inverseLocal());
//rotation.inverseLocal();
//return store;
}

/**
* <code>getParent</code> retrieves this node's parent. If the parent is
* null this is the root node.
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32 changes: 32 additions & 0 deletions jme3-core/src/test/java/com/jme3/scene/SpatialTest.java
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Expand Up @@ -31,6 +31,9 @@
*/
package com.jme3.scene;

import com.jme3.math.FastMath;
import com.jme3.math.Quaternion;
import com.jme3.math.Vector3f;
import com.jme3.scene.control.UpdateControl;
import org.junit.Assert;
import org.junit.Test;
Expand Down Expand Up @@ -119,4 +122,33 @@ public void testAddControlAt() {
Assert.assertEquals(testSpatial, control1.getSpatial());
Assert.assertEquals(testSpatial, control2.getSpatial());
}

@Test
public void testTransferToOtherNode(){
Node nodeA = new Node("nodeA");
Node nodeB = new Node("nodeB");
Node testNode=new Node("testNode");
nodeA.setLocalTranslation(-1,0,0);
nodeB.setLocalTranslation(1,0,0);
nodeB.rotate(0,90* FastMath.DEG_TO_RAD,0);
testNode.setLocalTranslation(1,0,0);
nodeA.attachChild(testNode);
Vector3f worldTranslation = testNode.getWorldTranslation().clone();
Quaternion worldRotation = testNode.getWorldRotation().clone();

Assert.assertTrue(worldTranslation.isSimilar(testNode.getWorldTranslation(),1e-6f));
Assert.assertTrue(worldRotation.isSimilar(testNode.getWorldRotation(),1e-6f));

nodeB.attachChild(testNode);

Assert.assertFalse(worldTranslation.isSimilar(testNode.getWorldTranslation(),1e-6f));
Assert.assertFalse(worldRotation.isSimilar(testNode.getWorldRotation(),1e-6f));

testNode.setLocalTranslation(nodeB.worldToLocal(worldTranslation,null));
Assert.assertTrue(worldTranslation.isSimilar(testNode.getWorldTranslation(),1e-6f));

testNode.setLocalRotation(nodeB.worldToLocal(worldRotation,null));
System.out.println(testNode.getWorldRotation());
Assert.assertTrue(worldRotation.isSimilar(testNode.getWorldRotation(),1e-6f));
}
}
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