MetalByTutorials/04-3d-transforms/projects/final/Matrices/Matrices/Renderer.swift

//
/**
 * Copyright (c) 2019 Razeware LLC
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * Notwithstanding the foregoing, you may not use, copy, modify, merge, publish,
 * distribute, sublicense, create a derivative work, and/or sell copies of the
 * Software in any work that is designed, intended, or marketed for pedagogical or
 * instructional purposes related to programming, coding, application development,
 * or information technology.  Permission for such use, copying, modification,
 * merger, publication, distribution, sublicensing, creation of derivative works,
 * or sale is expressly withheld.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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import MetalKit

class Renderer: NSObject {
  static var device: MTLDevice!
  static var commandQueue: MTLCommandQueue!
  var mesh: MTKMesh!
  var vertexBuffer: MTLBuffer!
  var pipelineState: MTLRenderPipelineState!
  
  var timer: Float = 0
  var uniforms = Uniforms()
  
  init(metalView: MTKView) {
    guard
      let device = MTLCreateSystemDefaultDevice(),
      let commandQueue = device.makeCommandQueue() else {
        fatalError("GPU not available")
    }
    Renderer.device = device
    Renderer.commandQueue = commandQueue
    metalView.device = device
    
    // Add the train mesh
    // Refer to the code in Chapter2.playground
    let allocator = MTKMeshBufferAllocator(device: device)
    guard let assetURL = Bundle.main.url(forResource: "train",
                                         withExtension: "obj") else {
                                          fatalError()
    }
    let vertexDescriptor = MTLVertexDescriptor()
    vertexDescriptor.attributes[0].format = .float3
    vertexDescriptor.attributes[0].offset = 0
    vertexDescriptor.attributes[0].bufferIndex = 0
    
    vertexDescriptor.layouts[0].stride = MemoryLayout<SIMD3<Float>>.stride
    let meshDescriptor =
      MTKModelIOVertexDescriptorFromMetal(vertexDescriptor)
    (meshDescriptor.attributes[0] as! MDLVertexAttribute).name = MDLVertexAttributePosition
    
    let asset = MDLAsset(url: assetURL,
                         vertexDescriptor: meshDescriptor,
                         bufferAllocator: allocator)
    let mdlMesh = asset.childObjects(of: MDLMesh.self).first as! MDLMesh
    do {
      mesh = try MTKMesh(mesh: mdlMesh, device: device)
    } catch let error {
      print(error.localizedDescription)
    }
    vertexBuffer = mesh.vertexBuffers[0].buffer

    let library = device.makeDefaultLibrary()
    let vertexFunction = library?.makeFunction(name: "vertex_main")
    let fragmentFunction = library?.makeFunction(name: "fragment_main")
    
    let pipelineDescriptor = MTLRenderPipelineDescriptor()
    pipelineDescriptor.vertexFunction = vertexFunction
    pipelineDescriptor.fragmentFunction = fragmentFunction
    pipelineDescriptor.vertexDescriptor =
      MTKMetalVertexDescriptorFromModelIO(mdlMesh.vertexDescriptor)
    pipelineDescriptor.colorAttachments[0].pixelFormat = metalView.colorPixelFormat
    do {
      pipelineState = try device.makeRenderPipelineState(descriptor: pipelineDescriptor)
    } catch let error {
      fatalError(error.localizedDescription)
    }
    
    super.init()
    metalView.clearColor = MTLClearColor(red: 1.0, green: 1.0,
                                         blue: 0.8, alpha: 1.0)
    metalView.delegate = self
    
    let translation = float4x4(translation: [0, 0.3, 0])
    let rotation = float4x4(rotation: [0, Float(45).degreesToRadians, 0])
    uniforms.modelMatrix = translation * rotation
    uniforms.viewMatrix = float4x4(translation: [0.8, 0, 0]).inverse
    mtkView(metalView, drawableSizeWillChange: metalView.bounds.size)
  }
}

extension Renderer: MTKViewDelegate {
  func mtkView(_ view: MTKView, drawableSizeWillChange size: CGSize) {
    let aspect = Float(view.bounds.width) / Float(view.bounds.height)
    let projectionMatrix =
      float4x4(projectionFov: Float(70).degreesToRadians,
               near: 0.001,
               far: 100,
               aspect: aspect)
    uniforms.projectionMatrix = projectionMatrix
  }
  
  func draw(in view: MTKView) {
    guard
      let descriptor = view.currentRenderPassDescriptor,
      let commandBuffer = Renderer.commandQueue.makeCommandBuffer(),
      let renderEncoder =
      commandBuffer.makeRenderCommandEncoder(descriptor: descriptor) else {
        return
    }
    
    uniforms.viewMatrix = float4x4(translation: [0, 0, -3]).inverse
    
    renderEncoder.setVertexBytes(&uniforms,
                                 length: MemoryLayout<Uniforms>.stride, index: 1)
    
    renderEncoder.setRenderPipelineState(pipelineState)
    renderEncoder.setVertexBuffer(vertexBuffer, offset: 0, index: 0)
    for submesh in mesh.submeshes {
      renderEncoder.drawIndexedPrimitives(type: .triangle,
                                          indexCount: submesh.indexCount,
                                          indexType: submesh.indexType,
                                          indexBuffer: submesh.indexBuffer.buffer,
                                          indexBufferOffset: submesh.indexBuffer.offset)
    }
    
    renderEncoder.endEncoding()
    guard let drawable = view.currentDrawable else {
      return
    }
    commandBuffer.present(drawable)
    commandBuffer.commit()
  }
}