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• ### Similar Content

• While working on a project using D3D12 I was getting an exception being thrown while trying to get a D3D12_CPU_DESCRIPTOR_HANDLE. The project is using plain C so it uses the COBJMACROS. The following application replicates the problem happening in the project.
#define COBJMACROS #pragma warning(push, 3) #include <Windows.h> #include <d3d12.h> #include <dxgi1_4.h> #pragma warning(pop) IDXGIFactory4 *factory; ID3D12Device *device; ID3D12DescriptorHeap *rtv_heap; int WINAPI wWinMain(HINSTANCE hinst, HINSTANCE pinst, PWSTR cline, int cshow) { (hinst), (pinst), (cline), (cshow); HRESULT hr = CreateDXGIFactory1(&IID_IDXGIFactory4, (void **)&factory); hr = D3D12CreateDevice(0, D3D_FEATURE_LEVEL_11_0, &IID_ID3D12Device, &device); D3D12_DESCRIPTOR_HEAP_DESC desc; desc.NumDescriptors = 1; desc.Type = D3D12_DESCRIPTOR_HEAP_TYPE_RTV; desc.Flags = D3D12_DESCRIPTOR_HEAP_FLAG_NONE; desc.NodeMask = 0; hr = ID3D12Device_CreateDescriptorHeap(device, &desc, &IID_ID3D12DescriptorHeap, (void **)&rtv_heap); D3D12_CPU_DESCRIPTOR_HANDLE rtv = ID3D12DescriptorHeap_GetCPUDescriptorHandleForHeapStart(rtv_heap); (rtv); } The call to ID3D12DescriptorHeap_GetCPUDescriptorHandleForHeapStart throws an exception. Stepping into the disassembly for ID3D12DescriptorHeap_GetCPUDescriptorHandleForHeapStart show that the error occurs on the instruction
mov  qword ptr [rdx],rax
which seems odd since rdx doesn't appear to be used. Any help would be greatly appreciated. Thank you.

• By lubbe75
As far as I understand there is no real random or noise function in HLSL.
I have a big water polygon, and I'd like to fake water wave normals in my pixel shader. I know it's not efficient and the standard way is really to use a pre-calculated noise texture, but anyway...
Does anyone have any quick and dirty HLSL shader code that fakes water normals, and that doesn't look too repetitious?

• Hi,
I finally managed to get the DX11 emulating Vulkan device working but everything is flipped vertically now because Vulkan has a different clipping space. What are the best practices out there to keep these implementation consistent? I tried using a vertically flipped viewport, and while it works on Nvidia 1050, the Vulkan debug layer is throwing error messages that this is not supported in the spec so it might not work on others. There is also the possibility to flip the clip scpace position Y coordinate before writing out with vertex shader, but that requires changing and recompiling every shader. I could also bake it into the camera projection matrices, though I want to avoid that because then I need to track down for the whole engine where I upload matrices... Any chance of an easy extension or something? If not, I will probably go with changing the vertex shaders.
• By NikiTo
Some people say "discard" has not a positive effect on optimization. Other people say it will at least spare the fetches of textures.

if (color.A < 0.1f) { //discard; clip(-1); } // tons of reads of textures following here // and loops too
Some people say that "discard" will only mask out the output of the pixel shader, while still evaluates all the statements after the "discard" instruction.

MSN>
discard: Do not output the result of the current pixel.
<MSN

As usual it is unclear, but it suggests that "clip" could discard the whole pixel(maybe stopping execution too)

I think, that at least, because of termal and energy consuming reasons, GPU should not evaluate the statements after "discard", but some people on internet say that GPU computes the statements anyways. What I am more worried about, are the texture fetches after discard/clip.

(what if after discard, I have an expensive branch decision that makes the approved cheap branch neighbor pixels stall for nothing? this is crazy)
• By NikiTo
I have a problem. My shaders are huge, in the meaning that they have lot of code inside. Many of my pixels should be completely discarded. I could use in the very beginning of the shader a comparison and discard, But as far as I understand, discard statement does not save workload at all, as it has to stale until the long huge neighbor shaders complete.
Initially I wanted to use stencil to discard pixels before the execution flow enters the shader. Even before the GPU distributes/allocates resources for this shader, avoiding stale of pixel shaders execution flow, because initially I assumed that Depth/Stencil discards pixels before the pixel shader, but I see now that it happens inside the very last Output Merger state. It seems extremely inefficient to render that way a little mirror in a scene with big viewport. Why they've put the stencil test in the output merger anyway? Handling of Stencil is so limited compared to other resources. Does people use Stencil functionality at all for games, or they prefer discard/clip?

Will GPU stale the pixel if I issue a discard in the very beginning of the pixel shader, or GPU will already start using the freed up resources to render another pixel?!?!

# DX12 [DX12] Unable to fix DXGI_ERROR_INVALID_CALL while calling CreateSwapChain

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I'm getting DXGI_ERROR_INVALID_CALL while calling CreateSwapChain. Here's my code to create command queue.

D3D12_COMMAND_QUEUE_DESC cqDesc = {};
SecureZeroMemory(&cqDesc, sizeof(cqDesc));
cqDesc.Type = D3D12_COMMAND_LIST_TYPE_DIRECT;
cqDesc.Flags = D3D12_COMMAND_QUEUE_FLAG_NONE;
SecureZeroMemory(&g_pCommandQueue, sizeof(g_pCommandQueue));
hr = g_pDevice->CreateCommandQueue(&cqDesc, IID_PPV_ARGS(&g_pCommandQueue));
if (FAILED(hr)) {
return false;
}

Here's where I'm calling CreateSwapChain()

DXGI_MODE_DESC bBuffDesc = {}; //To describe the display model.
SecureZeroMemory(&bBuffDesc, sizeof(bBuffDesc));
bBuffDesc.Height = Height; // ** Might have to give condition for windowed mode
bBuffDesc.Width = Width;
bBuffDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
bBuffDesc.RefreshRate.Denominator = Denominator;
bBuffDesc.RefreshRate.Numerator = Numerator;
bBuffDesc.ScanlineOrdering = DXGI_MODE_SCANLINE_ORDER_UNSPECIFIED;
bBuffDesc.Scaling = DXGI_MODE_SCALING_UNSPECIFIED;
DXGI_SAMPLE_DESC sampleDesc; //To describe multi-sampling preference.
sampleDesc.Count = 1; //We are not using multi-sampling. We take 1 sample per pixel.
sampleDesc.Quality = 0; // no antialiasing
DXGI_SWAP_CHAIN_DESC swapChainDesc = {}; //To describe the swap chain.
SecureZeroMemory(&swapChainDesc, sizeof(swapChainDesc));
swapChainDesc.BufferCount = g_cnFrameBufferCount;
swapChainDesc.BufferDesc = bBuffDesc;
swapChainDesc.SampleDesc = sampleDesc;
swapChainDesc.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT; //Tells the pipeline that this is a remder target and not a shader input.
swapChainDesc.OutputWindow = hwnd;
//swapChainDesc.Flags = DXGI_SWAP_CHAIN_FLAG_DISPLAY_ONLY;
//swapChainDesc.Windowed = false;
if (g_bWindowed) { // Windowed mode
swapChainDesc.Windowed = true;
}
else { //Full-Screen mode
swapChainDesc.Windowed = false;
}

SecureZeroMemory(&swapChainDesc, sizeof(swapChainDesc));

IDXGISwapChain * tempSwapChain = nullptr;

hr = dxgiFactory->CreateSwapChain(g_pCommandQueue, &swapChainDesc, &tempSwapChain);

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I haven’t had a chance to look into the details of Direct3D 12, but of note:

D3D12_COMMAND_QUEUE_DESC cqDesc = {};
SecureZeroMemory(&cqDesc, sizeof(cqDesc)); // USELESS.

DXGI_MODE_DESC bBuffDesc = {}; //To describe the display model.
SecureZeroMemory(&bBuffDesc, sizeof(bBuffDesc));  // USELESS.

DXGI_SWAP_CHAIN_DESC swapChainDesc = {}; //To describe the swap chain.
SecureZeroMemory(&swapChainDesc, sizeof(swapChainDesc)); // USELESS.

Why call SecureZeroMemory() on memory that is already set to 0? It only increases the risk that you accidentally buffer-overflow, and if it is not optimized out then it also wastes cycles.

This is not your problem, this time.  But worth mentioning.  Remove these calls to SecureZeroMemory().

L. Spiro

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Thanks Spiro :) Sure I'll remove that...

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An other thing I noted is that when I set swapChainDesc.Windowed = true (ie. Windowed mode) hr is giving S_OK

Edited by ngub05

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Same question as I had on your StackOverflow question. Why do you SecureZeroMemory your swapChainDesc *after* you've filled it out?

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Same question as I had on your StackOverflow question. Why do you SecureZeroMemory your swapChainDesc *after* you've filled it out?

Haha.. Happy to see you here too Adam. And of curse that was a mistake from my part. I've edited my SO Qn details, considering your suggestions. Here i haven't edited the question details to be in sync with your reply.  Still the problem persists. :(

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An other thing I noted is that when I set swapChainDesc.Windowed = true (ie. Windowed mode) hr is giving S_OK

If you want create a full-screen application you should call setFullscreenState and then calling ResizeBuffer on WM_SIZE message and not set windowed attribute of the swap-chain to false, instead you should first create a windowed application and then call ResizeBuffer after SetFullscreenState.

I was aware that setting windowed = false creates a borderless maximized window fullscreen window, but looks like this does not work very well..

EDIT: if you want to create a border-less maximized window instead, you must set the win32 style at the window creation and set the win32 window size to match and cover the screen size: instead using DWM this will enable dFlip/iFlip composition.

Edited by Alessio1989