I'm new to iOS development and I've got myself stumped. I am trying to render a cube using SceneKit that has a different colour for each face.
This is what I've got so far:
func sceneSetup() {
// 1
let scene = SCNScene()
// 2
let BoxGeometry = SCNBox(width: 0.9, height: 0.9, length: 0.9, chamferRadius: 0.0)
BoxGeometry.firstMaterial?.diffuse.contents = UIColor.redColor()
let cube = SCNNode(geometry: BoxGeometry)
cube.position = SCNVector3(x: 0, y: 0, z: -1)
scene.rootNode.addChildNode(cube)
// 3
sceneView.scene = scene
sceneView.autoenablesDefaultLighting = true
sceneView.allowsCameraControl = true
But I'd like each face to have a different colour. How do I do that?
The box is composed out of six different elements (one for each side). You may also have noticed that a geometry object has one property for the first material but also a property for an array of materials.
An object with multiple elements and multiple materials will pick the increment the material (and wrap) for each element.
For example 4 elements and 1 material
Element 1 2 3 4
Material 1 1 1 1
or 4 elements and 2 materials
Element 1 2 3 4
Material 1 2 1 2 // note that they are repeating
For example 4 elements and 7 materials
Element 1 2 3 4
Material 1 2 3 4 // (5, 6, 7) is unused
In the case of the box this means that you can use an array of six materials to have a unique material on each side of the box. I have an example of this in the sample code for one of the chapters for my Scene Kit book (in Objective-C):
// Each side of the box has its own color
// --------------------------------------
// All have the same diffuse and ambient colors to show the
// effect of the ambient light, even with these materials.
SCNMaterial *greenMaterial = [SCNMaterial material];
greenMaterial.diffuse.contents = [NSColor greenColor];
greenMaterial.locksAmbientWithDiffuse = YES;
SCNMaterial *redMaterial = [SCNMaterial material];
redMaterial.diffuse.contents = [NSColor redColor];
redMaterial.locksAmbientWithDiffuse = YES;
SCNMaterial *blueMaterial = [SCNMaterial material];
blueMaterial.diffuse.contents = [NSColor blueColor];
blueMaterial.locksAmbientWithDiffuse = YES;
SCNMaterial *yellowMaterial = [SCNMaterial material];
yellowMaterial.diffuse.contents = [NSColor yellowColor];
yellowMaterial.locksAmbientWithDiffuse = YES;
SCNMaterial *purpleMaterial = [SCNMaterial material];
purpleMaterial.diffuse.contents = [NSColor purpleColor];
purpleMaterial.locksAmbientWithDiffuse = YES;
SCNMaterial *magentaMaterial = [SCNMaterial material];
magentaMaterial.diffuse.contents = [NSColor magentaColor];
magentaMaterial.locksAmbientWithDiffuse = YES;
box.materials = @[greenMaterial, redMaterial, blueMaterial,
yellowMaterial, purpleMaterial, magentaMaterial];