Extracting vertices from scenekit

Question

I\'m having a problem with understanding scenekit geometery.

I have the default cube from Blender, and I export as collada (DAE), and can bring it into scenekit....

Answer 1

Here is an extension method if the data isn't contiguous (the vector size isn't equal to the stride) which can be the case when the geometry is loaded from a DAE file. It also doesn't use copyByte function.

extension  SCNGeometry{


    /**
     Get the vertices (3d points coordinates) of the geometry.

     - returns: An array of SCNVector3 containing the vertices of the geometry.
     */
    func vertices() -> [SCNVector3]? {

        let sources = self.sources(for: .vertex)

        guard let source  = sources.first else{return nil}

        let stride = source.dataStride / source.bytesPerComponent
        let offset = source.dataOffset / source.bytesPerComponent
        let vectorCount = source.vectorCount

        return source.data.withUnsafeBytes { (buffer : UnsafePointer) -> [SCNVector3] in

            var result = Array()
            for i in 0...vectorCount - 1 {
                let start = i * stride + offset
                let x = buffer[start]
                let y = buffer[start + 1]
                let z = buffer[start + 2]
                result.append(SCNVector3(x, y, z))
            }
            return result
        }
    }
}