SceneKit Black Screen for Basic Scene (Objective C)

Question

I am new to SceneKit. I am trying to create a basic scene. I have a model, lights, and camera. But for some reason I can't see my model. I've been searching for why this is happening, but I can't find anything.

Any direction appreciated.

My Setup is below:

art.scnassets - _models: Cube.scn - _textures: cubeFaces01.png, cubeFaces02.png, ...

GameViewController.h

#import <UIKit/UIKit.h>
#import <SceneKit/SceneKit.h>

@interface GameViewController : UIViewController

@end

GameViewController.m

//
//  GameViewController.m
//  PuzzleCube
//
//  Created by Robert Lee on 2016-04-30.
//  Copyright (c) 2016 Robert Lee. All rights reserved.
//

#import "GameViewController.h"

@implementation GameViewController{
@private

    // Scene
    SCNScene *_scene;

    // Manipulation Nodes
    SCNNode *_floorNode;
    SCNNode *_backdropNode;
    SCNNode *_cubeHandle;
    SCNNode *_cameraHandle;


}

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    [self setup];
}

#pragma mark - Setup

- (void)setup
{
    SCNView *sceneView = (SCNView *)self.view;

    // Redraw forever
    sceneView.playing = YES;
    sceneView.loops = YES;
    sceneView.showsStatistics = YES;
    sceneView.backgroundColor = [UIColor blackColor];


    // Setup the scene
    [self setupScene];

    // Initial Point of View
    sceneView.pointOfView = _cameraHandle;

    // Present the scene
    sceneView.scene = _scene;

}

- (void)setupScene
{
    _scene = [SCNScene scene];

    [self setupEnvironment];
    [self setupMainSceneElements];
}

- (void)setupEnvironment
{
    // Setup Main Floor Node
    SCNFloor *mainFloor = [SCNFloor floor];
    _floorNode = [SCNNode node];
    _floorNode.geometry = mainFloor;

    // Add to Main Scene
    [_scene.rootNode addChildNode:_floorNode];

}
# pragma mark - Setup Main Scene

- (void)setupMainSceneElements
{
    //
    // Scene Environment Elements
    //

    // Setup Main Backdrop Node
    SCNPlane *mainBackdrop = [SCNPlane planeWithWidth:20 height:20];
    _backdropNode = [SCNNode node];
    _backdropNode.geometry = mainBackdrop;
    _backdropNode.position = SCNVector3Make(200, 100, -200);


    //
    // Character Elements
    //

    // Cube Node
    [self setupCubeNodeCharacter];


    //
    // Static Elements
    //


    //
    // Lighting Elements
    //

    // Spot Light Node
    [self setupBasicLightingNodeLight];


    //
    // Camera Elements
    //

    // Main Camera Node
    [self setupCameraNodeCamera];




    //
    // Add to Main Scene
    //

    [_scene.rootNode addChildNode:_backdropNode];

}

# pragma mark -Character Elements

- (void)setupCubeNodeCharacter
{

    /*  Element Hierarchy:

        cubeHandle
          |_ cubeRotationY
           |_ cubePivot
            |_ cubeNode   
     */

    SCNScene *modelScene = [SCNScene sceneNamed:@"Cube.scn" inDirectory:@"assets.scnassets/_models" options:nil];
    SCNNode *_cubeNode = [modelScene.rootNode childNodeWithName:@"CubeGeometry" recursively:YES];

    SCNNode *cubeMesh = _cubeNode.childNodes[0];
    cubeMesh.hidden = YES;

    SCNNode *_cubePivot = [SCNNode node];
    SCNNode *_cubeRotationY = [SCNNode node];
    _cubeHandle = [SCNNode node];

    _cubeHandle.position =  SCNVector3Make(0, 0, 0);
    _cubeNode.position = SCNVector3Make(0, 0, 0);


    // Configure Element Hierarchy
    [_cubePivot addChildNode:_cubeNode];
    [_cubeRotationY addChildNode:_cubePivot];
    [_cubeHandle addChildNode:_cubeRotationY];


    // Offset Cube Handle position
    _cubeHandle.position = SCNVector3Make(_cubeHandle.position.x, _cubeHandle.position.y, _cubeHandle.position.z-50);


    //
    // Add to Main Scene
    //

    [_scene.rootNode addChildNode:_cubeHandle];

}

# pragma mark -Lighting Elements
-(void)setupBasicLightingNodeLight
{

    /*  Element Hierarchy:

     lightGroupNode
     |_ spotLight01Node
     |_ spotLight02Node
     |_ spotLight03Node
     |_ spotLight04Node

     */

    // Model file with Lights
    SCNScene *modelScene = [SCNScene sceneNamed:@"Cube.scn" inDirectory:@"assets.scnassets/_models" options:nil];

    // Light Group Container
    SCNNode *_lightGroupNode = [SCNNode node];
    _lightGroupNode.position = SCNVector3Make(0, 300, 0);

    // SpotLight Node 01
    SCNNode *_spotLight01Node = [modelScene.rootNode childNodeWithName:@"cubeSpotLight01" recursively:YES];

    // SpotLight Node 02
    SCNNode *_spotLight02Node = [modelScene.rootNode childNodeWithName:@"cubeSpotLight02" recursively:YES];

    // SpotLight Node 03
    SCNNode *_spotLight03Node = [modelScene.rootNode childNodeWithName:@"cubeSpotLight03" recursively:YES];

    // SpotLight Node 04
    SCNNode *_spotLight04Node = [modelScene.rootNode childNodeWithName:@"cubeSpotLight04" recursively:YES];

    // Configure Element Hierarchy
    [_lightGroupNode addChildNode:_spotLight01Node];
    [_lightGroupNode addChildNode:_spotLight02Node];
    [_lightGroupNode addChildNode:_spotLight03Node];
    [_lightGroupNode addChildNode:_spotLight04Node];


    //
    // Add to Main Camera
    //

    [_cameraHandle addChildNode:_lightGroupNode];

}

# pragma mark -Camera Elements
-(void)setupCameraNodeCamera
{
    /*  Element Hierarchy:

        cameraHandle
           |_ cameraOrientation
            |_ cameraNode   */

    // Attach camera from cube model file
    SCNScene *cubeModelScene = [SCNScene sceneNamed:@"Cube.scn" inDirectory:@"assets.scnassets/_models" options:nil];
    SCNNode *_cameraNode = [cubeModelScene.rootNode childNodeWithName:@"cubeCamera01" recursively:YES];
    SCNNode *_cameraOrientation = [SCNNode node];
    _cameraHandle = [SCNNode node];

    // Configure Element Hierarchy
    [_cameraOrientation addChildNode:_cameraNode];
    [_cameraHandle addChildNode:_cameraOrientation];


    //
    // Add to Main Scene
    //

    [_scene.rootNode addChildNode:_cameraHandle];



}

@end

Answer 1

In some cases, a light beam from the spotlight may not hit the model (due to its position, orientation, narrow light angle or soft edge). Therefore, use the default lighting to quickly turn the light on for the entire scene.

SCNView *sceneView = (SCNView *)self.view;

sceneView.autoenablesDefaultLighting = YES;