SceneKit中的pointSize属性被忽略

Question

我正在尝试使用SceneKit渲染点云（最终用于ARKit）。但是，我发现在尝试修改pointSize时会忽略minimumPointScreenSpaceRadius（和SCNGeometryElement）属性。有this解决方案来调用底层的OpenGL属性，但这似乎只适用于模拟。无论我放入什么pointSize，积分都是相同的。这大致就是我的代码的布局方式。我想知道我的GeometryElement设置是否有问题？

  var index: Int = 0  
    for x_pos in stride(from: start , to: end, by: increment) {  
        for y_pos in stride(from: start , to: end, by: increment) {  
            for z_pos in stride(from: start , to: end, by: increment) {  
                let pos:SCNVector3 = SCNVector3(x: x_pos, y: y_pos, z: z_pos)  
                positions.append(pos)  
                normals.append(normal)  
                indices.append(index)  
                index = index + 1  
            }  
        }  
    }  

    let pt_positions : SCNGeometrySource = SCNGeometrySource.init(vertices: positions)  
    let n_positions: SCNGeometrySource = SCNGeometrySource.init(normals: normals)  

    let pointer = UnsafeRawPointer(indices)  
    let indexData = NSData(bytes: pointer, length: MemoryLayout<Int32>.size * indices.count)  

    let elements = SCNGeometryElement(data: indexData as Data, primitiveType: .point, primitiveCount: positions.count, bytesPerIndex: MemoryLayout<Int>.size)  
    elements.pointSize = 10.0 //being ignored  
    elements.minimumPointScreenSpaceRadius = 10 //also being ignored  
    let pointCloud = SCNGeometry (sources: [pt_positions, n_positions], elements: [elements])  
    pointCloud.firstMaterial?.lightingModel = SCNMaterial.LightingModel.constant  


    let ptNode = SCNNode(geometry: pointCloud)  
    scene.rootNode.addChildNode(ptNode)  

Answer 1

您还应该同时指定element.minimumPointScreenSpaceRadius和element.maximumPointScreenSpaceRadius。如果是这样你的点大小工作！ :)