Metal program crashed - swift

Question

import PlaygroundSupport
import MetalKit
guard let device = MTLCreateSystemDefaultDevice() else {
fatalError("GPU is not supported")
}
let frame = CGRect(x: 0, y: 0, width: 600, height: 600)
let view = MTKView(frame: frame, device:device)
view.clearColor = MTLClearColor(red: 1, green: 1, blue: 0.8, alpha: 1)
//1
let allocator = MTKMeshBufferAllocator(device: device)
//2
let mdlMesh = MDLMesh(sphereWithExtent: [0.75, 0.75, 0.75], segments: [100, 100], inwardNormals: false, geometryType: .triangles, allocator: allocator)
//3
let mesh = try MTKMesh(mesh: mdlMesh, device: device)
guard let commandQueue = device.makeCommandQueue() else {
fatalError("Could not create a command queue")
}
//shader
let shader = """
#include <metal_stdlib>
using namespace metal;
struct VertexIn {
float4 position [[attribute(0)]];
};
vertex float4 vertex_main(const VertexIn vertex_in [[stage_in]])
{
return vertex_in.position;
}
fragment float4 fragment_main() {
return float4(1, 0, 0, 1);
}
"""
let library = try device.makeLibrary(source: shader, options: nil)
let vertexFunction = library.makeFunction(name: "vertex_main")
let fragmentFunction = library.makeFunction(name: "fragment_main")
//Pipeline
let pipelineDescriptor = MTLRenderPipelineDescriptor()
pipelineDescriptor.colorAttachments[0].pixelFormat = .bgra8Unorm
pipelineDescriptor.vertexFunction = vertexFunction
pipelineDescriptor.fragmentFunction = fragmentFunction
pipelineDescriptor.vertexDescriptor = MTKMetalVertexDescriptorFromModelIO(mesh.vertexDescriptor)
let pipelineState = try device.makeRenderPipelineState(descriptor: pipelineDescriptor)
// 1
guard let commandBuffer = commandQueue.makeCommandBuffer(),
//2
let renderPassDescriptor = view.currentRenderPassDescriptor,
//3
let renderEncoder = commandBuffer.makeRenderCommandEncoder(descriptor: renderPassDescriptor)
else { fatalError() }
guard let submesh = mesh.submeshes.first else {
fatalError()
}
//Here is where crashed.
renderEncoder.drawIndexedPrimitives(type: .triangle,
indexCount: submesh.indexCount,
indexType: submesh.indexType,
indexBuffer: submesh.indexBuffer.buffer,
indexBufferOffset: 0)
//1.u tell the render encoder that there are no more draw calls and end the render pass.
renderEncoder.endEncoding()
//2 u get the drawable from the MTKView.The MTKView is backed by a Core Animation CAMetalLayer and the layer owns a drawable texture which Metal can read and write to.
guard let drawable = view.currentDrawable else {
fatalError()
}
//3.Ask the command Buffer to present the MTKVIew's drawable and commit to the GPU
commandBuffer.present(drawable)
commandBuffer.commit()
PlaygroundPage.current.liveView = view
error: Execution was interrupted, reason: EXC_BAD_ACCESS (code=1, address=0x220).
The process has been left at the point where it was interrupted, use "thread return -x" to return to the state before expression evaluation.
I rewrite again in Xcode but still can not find where the problem is.
error: Execution was interrupted, reason: EXC_BAD_ACCESS (code=1, address=0x220). The process has been left at the point where it was interrupted, use "thread return -x" to return to the state before expression evaluation.
I rewrite again in Xcode but still can not find where the problem is.
error: Execution was interrupted, reason: EXC_BAD_ACCESS (code=1, address=0x220). The process has been left at the point where it was interrupted, use "thread return -x" to return to the state before expression evaluation.
I rewrite again in Xcode but still can not find where the problem is.

Answer 1

First there seems to be some XCode bug which forbids giving useful error information once your code crashes more than once, you just quit and restart it.
Now coming to main issues, you missed couple of things:
Setting render pipeline state on command encoder so that your shaders actually get to run by GPU
And setting vertex buffer to command encoder, so that GPU know what points of the mesh are needed to be rendered
I have updated your code below, also, you don't have to create most of those objects like pipeline, library, command queue every time. I'm assuming you are doing so just because it's a playground. I tried to add some basic structure to it in my sample below, you build upon it, like use MTKView delgates etc.
import UIKit
import PlaygroundSupport
import MetalKit
class BasicRenderer {
var mesh: MTKMesh
var pipelineState: MTLRenderPipelineState
var device: MTLDevice
var commandQueue: MTLCommandQueue
var metalView: MTKView
init() {
guard let device = MTLCreateSystemDefaultDevice() else {
fatalError("Can't create device")
}
self.device = device
guard let commandQueue = device.makeCommandQueue() else {
fatalError("Can't create commandQueue")
}
self.commandQueue = commandQueue
metalView = MTKView(frame: .zero, device: device)
metalView.clearColor = MTLClearColor(red: 1, green: 1, blue: 0.8, alpha: 1)
let meshAllocator = MTKMeshBufferAllocator(device: device)
let mdlMesh = MDLMesh(sphereWithExtent: [0.75, 0.75, 0.75],
segments: [100, 100],
inwardNormals: false,
geometryType: .triangles,
allocator: meshAllocator)
guard let mesh = try? MTKMesh(mesh: mdlMesh, device: device) else {
fatalError("Can't create mesh")
}
self.mesh = mesh
let shader = """
#include <metal_stdlib>
using namespace metal;
struct VertexIn {
float4 position [[attribute(0)]];
};
vertex float4 vertex_main(const VertexIn vertex_in [[stage_in]])
{
return vertex_in.position;
}
fragment float4 fragment_main() {
return float4(1, 0, 0, 1);
}
"""
guard let library = try? device.makeLibrary(source: shader, options: nil) else {
fatalError("Can't create library")
}
let vertexFunction = library.makeFunction(name: "vertex_main")
let fragmentFunction = library.makeFunction(name: "fragment_main")
let pipelineDescriptor = MTLRenderPipelineDescriptor()
pipelineDescriptor.colorAttachments[0].pixelFormat = .bgra8Unorm
pipelineDescriptor.vertexFunction = vertexFunction
pipelineDescriptor.fragmentFunction = fragmentFunction
pipelineDescriptor.vertexDescriptor = MTKMetalVertexDescriptorFromModelIO(mesh.vertexDescriptor)
guard let pipelineState = try? device.makeRenderPipelineState(descriptor: pipelineDescriptor) else {
fatalError("Can't create pipelineState")
}
self.pipelineState = pipelineState
}
func render(in size: CGSize) {
metalView.frame = CGRect(origin: .zero, size: size)
guard let commandBuffer = commandQueue.makeCommandBuffer(),
let renderPassDescriptor = metalView.currentRenderPassDescriptor,
let renderEncoder = commandBuffer.makeRenderCommandEncoder(descriptor: renderPassDescriptor)
else {
fatalError("Can't create commandBuffer/renderPassDescriptor/renderEncoder")
}
guard let subMesh = mesh.submeshes.first else {
fatalError("Can't get submesh")
}
guard let vertexBuffer = mesh.vertexBuffers.first?.buffer else {
fatalError("Can't get vertexBuffer")
}
// MARK: You missed setting pipeline state and vertex buffer on commandEncoder
renderEncoder.setRenderPipelineState(pipelineState)
renderEncoder.setVertexBuffer(vertexBuffer, offset: 0, index: 0)
renderEncoder.drawIndexedPrimitives(type: .triangle,
indexCount: subMesh.indexCount,
indexType: subMesh.indexType,
indexBuffer: subMesh.indexBuffer.buffer,
indexBufferOffset: 0)
renderEncoder.endEncoding()
guard let drawable = metalView.currentDrawable else {
fatalError("Can't get currentDrawable")
}
commandBuffer.present(drawable)
commandBuffer.commit()
}
}
class MyViewController : UIViewController {
var basicRenderer = BasicRenderer()
override func loadView() {
self.view = basicRenderer.metalView
basicRenderer.render(in: CGSize(width: 600, height: 600))
}
}
PlaygroundPage.current.liveView = MyViewController()