Reading a .cso (shader bytecode) file into an ID3DBlob | Together C & C++ | Page 1

visual mason Jul 1, 2023, 8:04 AM

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ComPtr<ID3DBlob> ReadToBlob()
{
    ComPtr<ID3DBlob> blob;
    D3DCreateBlob(file_size_, blob.GetAddressOf());

    stream_.read(reinterpret_cast<char*>(blob->GetBufferPointer()), blob->GetBufferSize());

    return blob;
}
```Is there anything wrong with this?
I'm trying to read a shader bytecode (`.cso`) file into a blob to pass to the pso, but it complains that "Encoded Vertex Shader size doesn't match specified size"

weak orioleBOT Jul 1, 2023, 8:04 AM

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visual mason Jul 1, 2023, 8:04 AM

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_stream is an std::ifstream

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file_size_ = std::filesystem::file_size(path)

snow stirrup Jul 1, 2023, 9:31 AM

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how do you open your stream?

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what's the actual problem?

visual mason Jul 1, 2023, 2:13 PM

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https://pastebin.com/crMEwupP

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line 61

snow stirrup Jul 1, 2023, 2:16 PM

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you wanna check whether reading actuality succeeds

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then you'll notice that it doesn't

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because you opened the file with ate mode and didn't rewind it

visual mason Jul 1, 2023, 2:26 PM

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snow stirrup because you opened the file with ate mode and didn't rewind it

https://pastebin.com/ANqFV3fb
same error again

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This loads the vertex shader correctly:cpp D3DReadFileToBlob(L"Default_vs.cso", vertex_shader_.GetAddressOf()); This doesn't :/```cpp
{
ScopedFileReader vs_reader("Default_vs.cso");
vertex_shader_ = vs_reader.ReadToBlob();
}

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"Encoded vertex shader size doesn't match specified size"
What is the "specified size"? vertex_shader_->GetBufferSize()?

viral stream Jul 1, 2023, 4:58 PM

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did you remember to open the stream in binary mode?

viral stream Jul 1, 2023, 5:14 PM

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ah you posted the whole code, and you did

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@visual mason can we see the CreateVertexShader calls etc. that fail?

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also, if you think the problem is in your code reading the file -- compare the data in the blob you read and the one D3DReadFileToBlob read

visual mason Jul 2, 2023, 3:40 AM

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viral stream also, if you think the problem is in your code reading the file -- compare the d...

bool comp_blobs(ID3DBlob* blob1, ID3DBlob* blob2)
{
    void* data1  = blob1->GetBufferPointer();
    void* data2  = blob2->GetBufferPointer();
    size_t size1 = blob1->GetBufferSize();
    size_t size2 = blob2->GetBufferSize();

    if (size1 != size2) { return false; }

    auto bytes1 = static_cast<unsigned char const*>(data1);
    auto  bytes2 = static_cast<unsigned char const*>(data2);

    for (size_t i = 0; i < size1; ++i) {
        if (bytes1[i] != bytes2[i]) {
            return false;
        }
    }

    return true;
}
```This returned false

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The problem's with the reader :/

visual mason Jul 2, 2023, 4:15 AM

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Seems the problem was the ScopedFileLock class

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Locking a file and reading from it causes corruption

snow stirrup Jul 2, 2023, 9:15 AM

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visual mason Locking a file and reading from it causes corruption

no, it just locks the file. you're not accessing the file through the handle you locked, you're not gonna be able to access the file through any other handle until you unlock it. that's what locking a file does ^^

visual mason Jul 2, 2023, 9:18 AM

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Ohhh

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That makes so much sense

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Is there a way to make an ifstream with the locked handle?

snow stirrup Jul 2, 2023, 9:30 AM

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why do you need to lock it anyways?

viral stream Jul 2, 2023, 12:28 PM

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Apparently MS' fstream has non-standard constructors, so you can construct one from a FILE*, and there are more MS specific functions you can use to get a FILE* for a HANDLE 😛
https://stackoverflow.com/a/476014

Stack Overflow

Can I use CreateFile, but force the handle into a std::ofstream?

Is there any way to take advantage of the file creation flags in the Win32 API such as FILE_FLAG_DELETE_ON_CLOSE or FILE_FLAG_WRITE_THROUGH as described here http://msdn.microsoft.com/en-us/library/

snow stirrup Jul 2, 2023, 1:49 PM

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just ReadFile instead of using streams when you're already using win32 anyways

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or just don't lock the file ^^

viral stream Jul 2, 2023, 1:50 PM

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but streams are so nice :^)

snow stirrup Jul 2, 2023, 1:52 PM

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they're just calling read on it once xD

visual mason Jul 3, 2023, 12:25 AM

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snow stirrup why do you need to lock it anyways?

For safety
This might be dumb, im not sure, but I was thinking of doing something like this:```cpp
struct Asset {
static void Init() {
// initialize the stream and lock the handle
}

static void Destroy() {
    // destroy the stream object and release the handle
}

static Asset& get(int id) {
    // read the file to get the asset at this id
}

private:
static std::ifstream stream_;
static HANDLE handle_;
}

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I want to be sure that I get the same result from Asset::get(21923) for every call

snow stirrup Jul 3, 2023, 12:30 AM

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why do you need to prevent the user from modifying the file while it's in use?

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you just read it once no?

visual mason Jul 3, 2023, 12:31 AM

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What if this file is really big

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like gigabytes

snow stirrup Jul 3, 2023, 12:32 AM

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what about it?

visual mason Jul 3, 2023, 12:33 AM

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Do you think its a good idea to load gigabytes worth of assets into the ram when all of it isn't needed immediately?

snow stirrup Jul 3, 2023, 12:34 AM

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ofc not

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i think that

if the user modifies the file of your game while it's running, that's on them, and
you're already opening the file with read sharing only, so no one else can write to the file while you've got it open anyways

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so locking the file in addition to the rest is already kinda redundant

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as i said, just use your already opened file handle to just ReadFile the contents

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you're already using the win32 api there

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no point in mixing that with iostream

#Reading a .cso (shader bytecode) file into an ID3DBlob