SceneKit SCNMaterial transparency not working on 11.2

I can confirm I'm also seeing this issue on iOS 11.2 – this functionality worked perfectly on previous versions of iOS. Did you submit a bug report/radar yet?

Yeah, I submitted a bug through the Bug Reporter and through the Feedback app on my test device weeks ago, but I've gotten no response yet.

I have found a temporary workaround and I've included the code below, but since Apple saw fit to release iOS 11.2 at the beginning of the weekend my game is completely broken until I can get an update out next week. Thanks, Apple.

        SCNSphere *cloudShell = [SCNSphere sphereWithRadius:planetRadius+0.125];
        SCNNode *cloudShellNode = [SCNNode nodeWithGeometry:cloudShell];
        [cloudShellNode setName:@"cloudsNode"];
        [atmosphereShellNode addChildNode:cloudShellNode];
 
        SCNMaterial *clouds = [SCNMaterial material];
        clouds.shininess = 0;
        clouds.diffuse.contents = [UIColor whiteColor];
        clouds.transparency = cloudLevel*0.9;
        clouds.transparent.contents = [UIImage imageNamed:@"Clouds"];
        clouds.transparencyMode = SCNTransparencyModeRGBZero; // <--- THE SOLUTION, AND CHANGE YOUR TEXTURE AS DESCRIBED BELOW
        cloudShell.materials = @[clouds];

In addition to adding that line of code, you have to change your texture image: instead of a PNG with alpha transparency, make it a solid image map where black is supposed to be opaque and white is supposed to be transparent. So, for my cloud map, it's an inverted-color image with black clouds on a solid white background. It also has to be saved as a JPG and not a PNG before you add it to Xcode, for some reason.

I know that as an indie developer Apple doesn't really care what I think, but this game is my livelihood and Apple just screwed over my 30,000 daily users without warning or explanation, and at the one time that I am least able to respond. I'm seriously furious at how this whole thing has gone down.

WARNING: The above code does NOT completely fix the issue after all. The white shell returns proportionately if the "transparency" float value is lower than 1, becoming completely opaque when "transparency" hits 0.

To achieve the proper result, I ended up using the above code, but changing "clouds.transparency = " to "cloudShellNode.opacity = " and setting "transparency" to 1.0 at all times.

That way, the "transparent.contents" mask works properly at all times, and I'm manipulating the opacity of the layer at the node-level, which isn't experiencing this bug. I've tested it as best I can, and this seems to have finally fixed it.

I'm also seeing a new issue in 11.2 related to an SCNMaterial with normal and multiply textures. It was a nice silvery moon in any version below 11.2, but is an ominous red blood moon in 11.2. Haven't had a chance to do any debugging as yet.

Although I love SceneKit, it does seems to specialize in undocumented behaviour changes - the depth buffer behaviour changed significantly in iOS 11 (huge reduction in the tolerated range of camera.zNear and .zFar), but nothing was ever documented about it, AFAIK.

Ran into the same issue ... Fixed it by first rendering the UIImage in a CALayer and then rendering the SCNMaterialProperty diffuse.contents as the CALayer (instead of directly as a UIImage)

Not sure if this will work with transparent, normal, or multiply texturing but it definitelty worked for diffuse

Hope this helps.

Thank you for posting this workaround. Starting with iOS 11.2, I experienced problems using UIImages as textures for transparency and diffuse, and first rendering the each UIImage to a CALayer appears to be working for me.

I am awarding you 200 Internet points.

Make sure you look at djsmartpicture's excellent workaround solution, below.

Great workaround, thanks. Here's an extension that implements it:

extension UIImage {
    func caLayer() -> CALayer {
        let layer = CALayer()
        layer.frame = CGRect(x:0, y:0, width:self.size.width, height:self.size.height)
        layer.contents = self.cgImage
        return layer
    }
}

Thank you for posting. Tryed this and it did change my texture into something that resembles a white noise pattern, so I guess that doesn't work for me...

Thanks, this worked for me!