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I'm new in Cocos3D and I have two questions concerning the parts of the 3D model.

As I understood, a .POD file consits of several parts. In my example, I have a 3D Car, which has the parts: - wheel - tire - class (etc.) and these parts have submeshes. I see this, when I open the pod file with PVRShaman.

Now my questions:

  1. Is it possible for me to have access to these parts? E.g. I want to change the color of the wheel. Can I do this programmatically?

  2. When I tap on a part, I want to know, on which part I have tapped. E.g. I want to tap on the wheel, and I know, that the wheel was selected. How can I do this?

Thank you very much!

Update: after the second proposal, my method looks like this:

-(void) nodeSelected: (CC3Node*) aNode byTouchEvent: (uint) touchType at: (CGPoint) touchPoint {
     NSLog(@"Node selected: %@", aNode.name);
     CC3Ray touchRay = [camera unprojectPoint: touchPoint];
     CC3NodePuncturingVisitor* puncturedNodes = [self nodesIntersectedByGlobalRay: touchRay];

     // The reported touched node may be a parent. We want to find the descendant node that
     // was actually pierced by the touch ray, so that we can attached a descriptor to it.
     CC3Node* localNode = puncturedNodes.closestPuncturedNode;

     NSLog(@"Node local: %@", localNode.name); 
}
Kara
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tralala
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2 Answers2

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Yes this is definitely possible.

Lets say you have a POD file of a car with doors, tires, steering wheel, etc.
If you want to access the tire of the car in cocos3d, you will need the name of the tire node, this should have been set in your 3d editor (maya, blender, etc).

Lets say you used maya and that you have set all four tire nodes names to:
L_back_tire, L_front_tire, R_back_tire, R_front_tire.

Then you would do this

//load car and all the child nodes of the car 
CC3PODResourceNode *car = [CC3PODResourceNode nodeFromFile:@"Car.pod"];
[self addChild:car];

//the car and all its child node (tires,doors,etc.) have been loaded into the scene
//so this is how you would fetch the left tire
CC3Node *leftTire = [car getNodeNamed:@"L_back_tire"];

//do more stuff with that tire her
tckmn
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zamfir
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  • Nice, this helped! But my problem now is, that if I tap on the car (e.g. on the wheel), in the method `-(void) nodeSelected: (CC3Node*) aNode byTouchEvent: (uint) touchType at: (CGPoint) touchPoint` of my Scene, aNode is "car.pod" and not "L_back_tire". How can I know on which part I tapped? But thanks for the first! – tralala Sep 15 '13 at 14:52
  • I now have set each submesh as touchable. This is very much effort, but the only thing I could do. So I used your first answer to get all submeshes and after that set each of them as touchable. – tralala Sep 20 '13 at 16:22
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CC3Ray touchRay = [self.activeCamera unprojectPoint: touchPoint];
CC3NodePuncturingVisitor* puncturedNodes = [self nodesIntersectedByGlobalRay: touchRay];

// The reported touched node may be a parent. We want to find the descendant node that
// was actually pierced by the touch ray, so that we can attached a descriptor to it.
CC3Node* localNode = puncturedNodes.closestPuncturedNode;`

The localNode will be the node that was closest to the touch.

I got this from the cocos3d DemoMashUp project.

I recommend you open up CC3DemoMashUpScene.m from the Cocos3dDemoMashUp and go look at the method -(void) markTouchPoint: (CGPoint) touchPoint on: (CC3Node*) aNode.
It's at the bottom of the file.

tckmn
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zamfir
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  • Thanks for this answer! But unfortunalety the localNode is always nil for me :( – tralala Sep 15 '13 at 18:15
  • Is it always nil? even when you touch on big parent objects? and also this code should be in your `-(void) nodeSelected: (CC3Node*) aNode byTouchEvent: (uint) touchType at: (CGPoint) touchPoint` – zamfir Sep 16 '13 at 01:45
  • Yes unfortunately it is always nil :( and I have it in this method, like you see now in the updated question. aNode is not nil, but it is only the parent mesh and I want to detect the children. – tralala Sep 17 '13 at 13:11
  • Try touching randomly all over the car and even the scene, and then see if localNode is always nil on every single touch. – zamfir Sep 19 '13 at 13:00