SceneKit SCNGeometryElement TriangleStrip 与三角形 [英] SceneKit SCNGeometryElement TriangleStrip vs triangles

问题描述

我绘制了一个包含 SCNGeometryElement 对象的场景.(这是一个地形.我每个网格项目有 2 个三角形)为了优化，我决定用 TriangleStrip 替换我的三角形基元.但它没有给我相同的结果

I have draw a scene which contains a SCNGeometryElement object. (it is a terrain. I have 2 triangles per grid item) In order to optimize, i decided to remplace my triangle primitive by TriangleStrip. But it does not give me the same result

我的顶点数组是连续的 4 个点:

My Vertex array is a succession of 4 points:

C  D
A  B

我的索引数组包含 A、C、B 和 D 的索引因此，当我使用 TriangleStrip 时，场景套件应该绘制 ACB 和 CBD 三角形.这是苹果文档中所说的.

My indices array contains index of A, C, B and D So when i work with TriangleStrip, scene kit is supposed to draw ACB and CBD triangles. That is what is said in apple documentation.

我想知道应该在primitivecount中放什么.我尝试了几件事.它改变了渲染，但我无法用简单的三角形检索到与之前相同的结果......

I am wondering what i should put in primitivecount. I tried several things. It changes the rendering but i can not retrieve the same result i had before with simple triangles...

有什么想法吗?

谢谢

let element = SCNGeometryElement(data: buffer_indices , primitiveType: .TriangleStrip, primitiveCount: Int(points_count), bytesPerIndex: sizeof(CInt))

推荐答案

对于三角形条带，primitiveCount 应该等于 indexCount - 2.

For a triangle strip the primitiveCount should be equal to indexCount - 2.

或者，您可以使用 Swift 友好的 SCNGeometryElement(indices:originalType:)(另见这篇文章).

Alternatively you can use the Swift-friendly SCNGeometryElement(indices:primitiveType:) (see also this post).

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