scenekit - zoom in/out to selected node of scene

Question

I have a scene in which a human body is displayed. I want to zoom in to a specific body part when a user taps on it.

I changed the position of the camera to the position of Node but it points not exactly on it.

Also I need to keep the selected part in center of the screen when zoom in.

How can I accomplish zoom in / out?

Are the different body parts different nodes or are the entire body an node? — Vollan, Apr 17 '18 at 06:07
They all exist in one node, they are subparts of a main node — Hassy, Apr 17 '18 at 06:12
That sounds contradicting. Are you saying they are child nodes inside a parent node? — Vollan, Apr 17 '18 at 06:22

score 2 · Accepted Answer · answered Apr 18 '18 at 12:22

I solved my problem by moving the camera instead of scaling the Model. I got the tap point by Gesture Recognizer and similarly the point of touch.

Now I converted the View-Coordinates to Scene Coordinates

CGPoint p = [gestureRecognize locationInView:scnView];

    NSArray *hitResults = [scnView hitTest:p options:nil];

    SCNVector3 projectedOrigin = [scnView projectPoint:SCNVector3Zero];

    SCNVector3 vector = SCNVector3Make(p.x, p.y, projectedOrigin.z);

    SCNVector3 worldPoint = [scnView unprojectPoint:vector];

and then positioned the Camera to the worldPoint.

Can you please suggest how did you positioned the camera? – Dhruv May 15 '20 at 04:54 — Dhruv, May 15 '20 at 04:54

Vollan · Answer 2 · 2018-04-18T11:25:25.753

1

To reposition it in a Z-axis you want to multiply the currents node matrix with the new matrix.

var node = childNode.transform
var translation = SCNMatrix4MakeTranslation(1.0, 1.0, adjustedZValue)
var newTrans = SCNMatrix4Mult(node, translation)
childNode.transform = newTrans

Edit: Had some names mixed up

edited Apr 18 '18 at 11:25

answered Apr 17 '18 at 07:30

Vollan

1,887
11
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It will just scale to sub node. I will try using scaling and positioning. – Hassy Apr 18 '18 at 10:29

score 1 · Answer 3 · answered Feb 24 '19 at 14:41

a bit cleaned up and more "swifty":

let transform = childNode.transform
let adjustedZValue = Float32(3)
let translation = SCNMatrix4MakeTranslation(1.0, 1.0, adjustedZValue)
let newTrans = SCNMatrix4Mult(transform, translation)
childNode.transform = newTrans

scenekit - zoom in/out to selected node of scene

3 Answers3

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