我正在尝试加载模型(表单 .OBJ)并使用 MetalKit 在 iOS 上将其绘制到屏幕上。问题是我得到了一些随机多边形而不是我的模型......这是倾向于加载模型的代码(代码基于raywenderlich.com的教程:
let allocator = MTKMeshBufferAllocator(device: device)
let vertexDescriptor = MDLVertexDescriptor()
let vertexLayout = MDLVertexBufferLayout()
vertexLayout.stride = sizeof(Vertex)
vertexDescriptor.layouts = [vertexLayout]
vertexDescriptor.attributes = [MDLVertexAttribute(name: MDLVertexAttributePosition, format: MDLVertexFormat.Float3, offset: 0, bufferIndex: 0),
MDLVertexAttribute(name: MDLVertexAttributeColor, format: MDLVertexFormat.Float4, offset: sizeof(float3), bufferIndex: 0),
MDLVertexAttribute(name: MDLVertexAttributeTextureCoordinate, format: MDLVertexFormat.Float2, offset: sizeof(float3)+sizeof(float4), bufferIndex: 0),
MDLVertexAttribute(name: MDLVertexAttributeNormal, format: MDLVertexFormat.Float3, offset: sizeof(float3)+sizeof(float4)+sizeof(float2), bufferIndex: 0)]
var error: NSError?
let asset = MDLAsset(URL: path, vertexDescriptor: vertexDescriptor, bufferAllocator: allocator, preserveTopology: true, error: &error)
if error != nil{
print(error)
return nil
}
let model = asset.objectAtIndex(0) as! MDLMesh
let mesh = try MTKMesh(mesh: model, device: device)
这是我的绘图方法:
func render(commandQueue: MTLCommandQueue, pipelineState: MTLRenderPipelineState,drawable: CAMetalDrawable,projectionMatrix: float4x4,modelViewMatrix: float4x4, clearColor: MTLClearColor){
dispatch_semaphore_wait(bufferProvider.availibleResourcesSemaphore, DISPATCH_TIME_FOREVER)
let renderPassDescriptor = MTLRenderPassDescriptor()
renderPassDescriptor.colorAttachments[0].texture = drawable.texture
renderPassDescriptor.colorAttachments[0].loadAction = .Clear
renderPassDescriptor.colorAttachments[0].clearColor = clearColor
renderPassDescriptor.colorAttachments[0].storeAction = .Store
let commandBuffer = commandQueue.commandBuffer()
commandBuffer.addCompletedHandler { (buffer) in
dispatch_semaphore_signal(self.bufferProvider.availibleResourcesSemaphore)
}
let renderEncoder = commandBuffer.renderCommandEncoderWithDescriptor(renderPassDescriptor)
renderEncoder.setCullMode(MTLCullMode.None)
renderEncoder.setRenderPipelineState(pipelineState)
renderEncoder.setVertexBuffer(vertexBuffer, offset: 0, atIndex: 0)
renderEncoder.setFragmentTexture(texture, atIndex: 0)
if let samplerState = samplerState{
renderEncoder.setFragmentSamplerState(samplerState, atIndex: 0)
}
var nodeModelMatrix = self.modelMatrix()
nodeModelMatrix.multiplyLeft(modelViewMatrix)
uniformBuffer = bufferProvider.nextUniformsBuffer(projectionMatrix, modelViewMatrix: nodeModelMatrix, light: light)
renderEncoder.setVertexBuffer(self.uniformBuffer, offset: 0, atIndex: 1)
renderEncoder.setFragmentBuffer(uniformBuffer, offset: 0, atIndex: 1)
if indexBuffer != nil{
renderEncoder.drawIndexedPrimitives(.Triangle, indexCount: self.indexCount, indexType: self.indexType, indexBuffer: self.indexBuffer!, indexBufferOffset: 0)
}else{
renderEncoder.drawPrimitives(.Triangle, vertexStart: 0, vertexCount: vertexCount, instanceCount: vertexCount/3)
}
renderEncoder.endEncoding()
commandBuffer.presentDrawable(drawable)
commandBuffer.commit()
}
这是我的顶点着色器:
struct VertexIn{
packed_float3 position;
packed_float4 color;
packed_float2 texCoord;
packed_float3 normal;
};
struct VertexOut{
float4 position [[position]];
float3 fragmentPosition;
float4 color;
float2 texCoord;
float3 normal;
};
struct Light{
packed_float3 color;
float ambientIntensity;
packed_float3 direction;
float diffuseIntensity;
float shininess;
float specularIntensity;
};
struct Uniforms{
float4x4 modelMatrix;
float4x4 projectionMatrix;
Light light;
};
vertex VertexOut basic_vertex(
const device VertexIn* vertex_array [[ buffer(0) ]],
const device Uniforms& uniforms [[ buffer(1) ]],
unsigned int vid [[ vertex_id ]]) {
float4x4 mv_Matrix = uniforms.modelMatrix;
float4x4 proj_Matrix = uniforms.projectionMatrix;
VertexIn VertexIn = vertex_array[vid];
VertexOut VertexOut;
VertexOut.position = proj_Matrix * mv_Matrix * float4(VertexIn.position,1);
VertexOut.fragmentPosition = (mv_Matrix * float4(VertexIn.position,1)).xyz;
VertexOut.color = VertexIn.color;
VertexOut.texCoord = VertexIn.texCoord;
VertexOut.normal = (mv_Matrix * float4(VertexIn.normal, 0.0)).xyz;
return VertexOut;
}
这是它的样子:
实际上,我还有一个完全由我编写的用于加载模型的类。它工作正常,问题是它没有使用索引,所以如果我尝试加载比低多边形球体更复杂的模型,GPU 崩溃......无论如何我试图修改它以使用索引并且我得到了同样的结果..比我添加硬编码索引进行测试,我得到了一个非常奇怪的结果。当我有 3 个索引时,它绘制了一个三角形,当我再添加 3 个时,它绘制了相同的三角形,在再增加 3 个顶点后,它绘制了 2 个三角形......
编辑:
这是我的Vertex
结构:
struct Vertex:Equatable{
var x,y,z: Float
var r,g,b,a: Float
var s,t: Float
var nX,nY,nZ:Float
func floatBuffer()->[Float]{
return [x,y,z,r,g,b,a,s,t,nX,nY,nZ]
}
}