swift – ModelIO框架不起作用

我试图进口Melita茶壶,但我也有一个“爆炸”的面孔,而不是标志性的茶叶冲泡设备.在阅读MDLVertexBufferLayout的文档后,我找到了解决方案：

通过查看MDLVertexDescriptor的默认实现的.layouts和.attributes属性,他们为每个属性类型创建一个缓冲区(如上面的引用,第一种情况),我想使用混合模式.

我用我自己的数组手动设置.layouts和.attributes然后,我得到了……半个梅丽塔锅？

class func setup(meshWithDevice device: MTLDevicE) -> MTKMesh
{
    // Allocator
    let allocator = MTKMeshBufferAllocator(device: devicE)

    // Vertex Descriptor,tells the MDLAsset how to layout the buffers
    let vertexDescriptor = MDLVertexDescriptor()

    // Vertex Buffer Layout,tells how many buffers will be used,and the Stride of its structs
    // (the init(stide: int) crashes in the Beta)
    let vertexLayout = MDLVertexBufferLayout()
    vertexLayout.Stride = MemoryLayout<Vertex>.size

    // Apply the Layouts
    vertexDescriptor.layouts = [vertexLayout]

    // Apply the attributes,in my case,position and normal (float4 x2)
    vertexDescriptor.attributes =
    [
        MDLVertexAttribute(name: MDLVertexAttributePosition,format: MDLVertexFormat.float4,offset: 0,bufferIndex: 0),MDLVertexAttribute(name: MDLVertexAttributeNormal,offset: MemoryLayout<float4>.size,bufferIndex: 0)
    ]

    var error : NSError? = nil

    // Load the teapot
    let asset = MDLAsset(url: Bundle.main.url(forresource: "teapot",withExtension: "obj")!,vertexDescriptor: vertexDescriptor,bufferAllocator: allocator,preserveTopology: true,error: &error)

    if let error = error
    {
        print(error)
    }

    // Obtain the teapot Mesh
    let teapotModel = asset.object(at: 0) as! MDLMesh

    // Convert into MetalKit Mesh,insted of ModelIO
    let teapot = try! MTKMesh(mesh: teapotModel,device: devicE)

    return teapot
}

(XCode 8 Beta 6中的Swift 3.0)

如果我设法渲染整个内容,我会更新我的帖子.

编辑：立即工作

WHelp,这个bug就在我的最后,我在索引计数中错了：

//// Buffers
renderPass.setVertexBuffer(mesh.vertexBuffers[0].buffer,at: 0)
renderPass.setVertexBuffer(uniformBuffer,at: 1)

let submesh   = mesh.submeshes[0]
let indexSize = submesh.indexType == .uInt32 ? 4 : 2

//// Draw InDices
renderPass.drawIndexedPrimitives(submesh.primitiveType,indexCount:  submesh.indexBuffer.length / indexSize,indexType:   submesh.indexType,indexBuffer: submesh.indexBuffer.buffer,indexBufferOffset: 0)

问题是让indexSize = submesh.indexType == .uInt32？ 4：2,在我做右边32:16之前,但.length属性以字节而不是位,所以很笨.

无论如何,我设法用Metal加载一个Obj文件,所以问题是：我上面提到的每个属性的单独缓冲,或者代码中完全不同的问题.