iOS 11 SceneKit hitTest:options: fails

问题

I'm facing a difficult situation using hitTest:options: in SceneKit on iOS 11.

In a maping application I have a terrain node. Using hitTest:options: I was able for long to spot a point on the terrain from a touch on the screen. It still work as expected with released binary on iOS 11, and also on Xcode 9 compiled binary for iOS 10 simulator.

But iOS 11 binary on iOS 11 SDK gives totaly eratic results. Return array from hitTest:options: may contain no result or too many. Moreover, most of the time none of the results is valid. Here below are images to illustrate the point. All image are from a scene with no hidden node.

Edit: I made a test today using hitTestWithSegmentFromPoint:toPoint:options: and got false results also.

First with working simulator.

It shows a normal hit on the terrain. The hit point is illustrated with a red ball. It is half inset in the terrain as its center is right on the terrain.

These two images show a case where the "ray" cross the terrain 3 times. We got 3 hits all placed correctly on the terrain.The second image change the angle of view to show the 3 points.

Now the failing iOS 11 situation:

On this picture we got one hit but it is "nowhere" between the two mountains, not on the terrain.

The last two pictures show other attempts with 4 and 16 hits, all "in the blue" with no connection to the terrain.

Sometimes the hit are "away" past the terrain, sometimes they are between the camera and the terrain.

回答1:

I was facing the same problem on iOS 11. My solution:

var hitTestOptions = [SCNHitTestOption.sortResults : NSNumber(value: true),
                      SCNHitTestOption.boundingBoxOnly : NSNumber(value: true)]

if #available(iOS 11.0, *) {
    hitTestOptions[SCNHitTestOption.searchMode] = SCNHitTestSearchMode.all.rawValue as NSNumber
}

来源：https://stackoverflow.com/questions/46352867/ios-11-scenekit-hittestoptions-fails