SceneKit - SCNText centering incorrectly

Question

I have tried to make a text string (SCNText) fit inside a box (SCNBox) in the code below. The size of the box looks correct but the text is not in the right center of the bo

Answer 1

To find the center of the bounding box you need to add (not subtract) the min and max before you divide by 2.

textNode.position = SCNVector3(x: (minVec.x + maxVec.x) / 2, y: minVec.y + maxVec.y, z: 0)

Answer 2

The difference of SCNText from other geometries is that SCNText origin point positioned at bottom left corner. In other geometries, it is a bottom center.

To fix text position in parent node you can set its pivotPoint.x to half of width:

SCNVector3 min, max;
[textNode getBoundingBoxMin:&min max:&max];
textNode.pivot = SCNMatrix4MakeTranslation((max.x - min.x) / 2, 0, 0);

To fix subnodes position, you should set their position to half of width plus min:

SCNVector3 min, max;
[textNode getBoundingBoxMin:&min max:&max];
subnode.position = SCNVector3Make((max.x - min.x) / 2 + min.x, (max.y - min.y) / 2 + min.y, 0);

Answer 3

I think you might be getting bitten by SCNText's unusual treatment of origin. IIRC the Y zero is at the string's baseline, not at the bottom of the descenders.

Turn on showBoundingBoxes In the debugOptions and see if that helps.

Answer 4

Swift: center text-node in parent-node correctly

let (min, max) = textNode.boundingBox

let dx = min.x + 0.5 * (max.x - min.x)
let dy = min.y + 0.5 * (max.y - min.y)
let dz = min.z + 0.5 * (max.z - min.z)
textNode.pivot = SCNMatrix4MakeTranslation(dx, dy, dz)

let textNodeParent = SCNNode()
textNodeParent.addChildNode(textNode)