100 lines
3.1 KiB
Swift
100 lines
3.1 KiB
Swift
import PlaygroundSupport
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import MetalKit
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guard let device = MTLCreateSystemDefaultDevice() else {
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fatalError("GPU is not supported")
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}
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let frame = CGRect(x: 0, y: 0, width: 600, height: 600)
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let view = MTKView(frame: frame, device: device)
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view.clearColor = MTLClearColor(red: 1, green: 1, blue: 0.8, alpha: 1)
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view.device = device
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guard let commandQueue = device.makeCommandQueue() else {
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fatalError("Could not create a command queue")
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}
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let allocator = MTKMeshBufferAllocator(device: device)
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guard let assetURL = Bundle.main.url(forResource: "train",
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withExtension: "obj") else {
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fatalError()
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}
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let vertexDescriptor = MTLVertexDescriptor()
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vertexDescriptor.attributes[0].format = .float3
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vertexDescriptor.attributes[0].offset = 0
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vertexDescriptor.attributes[0].bufferIndex = 0
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vertexDescriptor.layouts[0].stride = MemoryLayout<SIMD3<Float>>.stride
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let meshDescriptor =
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MTKModelIOVertexDescriptorFromMetal(vertexDescriptor)
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(meshDescriptor.attributes[0] as! MDLVertexAttribute).name =
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MDLVertexAttributePosition
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let asset = MDLAsset(url: assetURL,
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vertexDescriptor: meshDescriptor,
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bufferAllocator: allocator)
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let mdlMesh = asset.childObjects(of: MDLMesh.self).first as! MDLMesh
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let mesh = try MTKMesh(mesh: mdlMesh, device: device)
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let shader = """
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#include <metal_stdlib> \n
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using namespace metal;
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struct VertexIn {
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float4 position [[ attribute(0) ]];
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};
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vertex float4 vertex_main(const VertexIn vertex_in [[ stage_in ]]) {
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return vertex_in.position;
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}
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fragment float4 fragment_main() {
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return float4(1, 0, 0, 1);
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}
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"""
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let library = try device.makeLibrary(source: shader, options: nil)
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let vertexFunction = library.makeFunction(name: "vertex_main")
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let fragmentFunction = library.makeFunction(name: "fragment_main")
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let pipelineDescriptor = MTLRenderPipelineDescriptor()
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pipelineDescriptor.colorAttachments[0].pixelFormat = .bgra8Unorm
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pipelineDescriptor.vertexFunction = vertexFunction
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pipelineDescriptor.fragmentFunction = fragmentFunction
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pipelineDescriptor.vertexDescriptor = MTKMetalVertexDescriptorFromModelIO(mesh.vertexDescriptor)
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let pipelineState = try device.makeRenderPipelineState(descriptor: pipelineDescriptor)
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guard let commandBuffer = commandQueue.makeCommandBuffer(),
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let renderPassDescriptor = view.currentRenderPassDescriptor,
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let renderEncoder =
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commandBuffer.makeRenderCommandEncoder(descriptor: renderPassDescriptor)
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else { fatalError() }
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renderEncoder.setRenderPipelineState(pipelineState)
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renderEncoder.setVertexBuffer(mesh.vertexBuffers[0].buffer,
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offset: 0, index: 0)
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renderEncoder.setTriangleFillMode(.lines)
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for submesh in mesh.submeshes {
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renderEncoder.drawIndexedPrimitives(
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type: .triangle,
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indexCount: submesh.indexCount,
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indexType: submesh.indexType,
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indexBuffer: submesh.indexBuffer.buffer,
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indexBufferOffset: submesh.indexBuffer.offset
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)
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}
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renderEncoder.endEncoding()
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guard let drawable = view.currentDrawable else {
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fatalError()
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}
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commandBuffer.present(drawable)
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commandBuffer.commit()
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PlaygroundPage.current.liveView = view
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