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I am trying to load my data from a binary file (ppm) and create a texture using this data. It is important that I learn to do it this way as I am eventually going to be packing all of my textures into a single binary file and then index them so creating the texture with pure binary data is something that I need to be able to do.

It seems that the texture is drawing correctly, but the colours are incorrect. I saved my image as .ppm just for this test application.

Here is the code to load my data

ppm ppm;

ppm.read(std::string("textureppm.ppm"));

//just to ensure the data is correct
uint32_t val = ppm.pixels[0];
unsigned char r = (val & 0xFF000000) >> 24;
unsigned char g = (val & 0x00FF0000) >> 16;
unsigned char b = (val & 0x0000FF00) >> 8;
unsigned char a = (val & 0x000000FF);

ID3D11ShaderResourceView* texSRV = nullptr;
D3D11_SUBRESOURCE_DATA initData = { &ppm.pixels, ppm.width * sizeof(uint32_t), 0};

D3D11_TEXTURE2D_DESC desc = {};
desc.Width = ppm.width; desc.Height = ppm.height; desc.MipLevels = 1; desc.ArraySize = 1;
desc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
desc.SampleDesc.Count = 1;
desc.Usage = D3D11_USAGE_IMMUTABLE;
desc.BindFlags = D3D11_BIND_SHADER_RESOURCE;

ID3D11Texture2D* tex;
HRESULT hr = getDevice()->CreateTexture2D(&desc, &initData, &tex);

if (SUCCEEDED(hr))
{
    D3D11_SHADER_RESOURCE_VIEW_DESC SRVDesc = {};
    SRVDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
    SRVDesc.ViewDimension = D3D11_SRV_DIMENSION_TEXTURE2D;
    SRVDesc.Texture2D.MipLevels = 1;

    hr = getDevice()->CreateShaderResourceView(tex,
        &SRVDesc, &texSRV);
}

if (FAILED(hr)) {
    throw 0;
}
else {
    setTexture(texSRV);
}

I have packed each byte into a uint32_t as it seems that is the format that is required DXGI_FORMAT_R8G8B8A8_UNORM

Here is the packing

uint32_t ppm::CreateRGBA(unsigned char r, unsigned char g, unsigned char b, unsigned char a)
{
    uint32_t value = 0;
    int r2 = (r & 0xff) << 24;
    int g2 = (g & 0xff) << 16;
    int b2 = (b & 0xff) << 8;
    int a2 = (a & 0xff);

    value += r2 + g2 + b2 + a2;

    return value;
}

This code produces the following texture enter image description here

When the original texture is enter image description here

Does anyone know what I am doing wrong?

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1 Answer 1

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enter image description here

It seems the packing order of the uint_32 value was incorrect. I thought the packing should be RGBA left to right, rather than ABGR.

Switching the packing order around fixed this issue.

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    \$\begingroup\$ Man, I've been there! I've done this a few times. Glad you figured it out! \$\endgroup\$ Commented Feb 16, 2019 at 21:45
  • \$\begingroup\$ Since you're most likely on a little-endian system, a color packed as an rrggbbaa integer will be stored as aabbggrr in memory, thats why it's the wrong way around. \$\endgroup\$
    – tkausl
    Commented Feb 17, 2019 at 12:14

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