CODEWITHSUNDEEP
iosobjective-cscenekit
Max
Max

Reputation: 2749

How to set the level of detail / smoothness / subdivision rate for SCNShape?

I am currently trying to render a circle with SCNShapeNode in SceneKit. But unfortunately it does not render a perfect circle but an octagon.

Is there any way to set the render detail for SCNShape? 

UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter: CGPointMake(0, 0) radius: 2 startAngle: 0.0 endAngle: M_PI * 2.0f clockwise: NO];

SCNShape *shape = [SCNShape shapeWithPath:path extrusionDepth: 1.0];
shape.firstMaterial.diffuse.contents = [UIColor colorWithRed: 1.0 green:0.0 blue:0.0 alpha:1.0];    

SCNNode *shapeNode = [SCNNode nodeWithGeometry: shape];
[scene.rootNode addChildNode: shapeNode];

Upvotes: 3

Views: 1260

Answers (1)

rickster
rickster

Reputation: 126107

From the docs:

The path’s flatness (see setFlatness: in NSBezierPath Class Reference) determines the level of detail SceneKit uses in building a three-dimensional shape from the path—a larger flatness value results in fewer polygons to render, increasing performance.

Conversely, a lower flatness value results in a smoother shape.

Bezier path flatness is an odd fit for this API because it measures in terms of pixels/points, and by default a "point" for an SCNShape is one unit of scene (or local node) space. So if your shape is 10 scene units wide, it's like trying to render a path in 10 pixels in 2D... You need a really low flatness value for it to be smooth.

To answer the question in your non-answer: the subdivisionLevel stuff and edge creases business aren't really for use with SCNShape — they're for custom geometry that's designed for use with subdivision surface rendering.

Upvotes: 6

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