MapSubresource() returning incorrectly sized databox ?

Graphics and GPU Programming Programming

Started by Gavin Williams June 16, 2012 07:37 PM

2 comments, last by 21st Century Moose 11 years, 10 months ago

986

Author

June 16, 2012 07:37 PM

Hi again,

I've loaded a texture 32 x 32 with Format.R8G8B8A8_UNorm. When i MapSubresource() into a DataBox, the databox has a row-pitch of 256 and a slice-pitch of 8192. That seems incorrect to me as the format has a width of 4 bytes.

When I perform the following operation, my textures are striped with zero's (horizontal black lines). I believe MapSubresource is incorrectly mapping the texture.



	    if (GetFormatType(format) == FormatModifiers.UNorm)

	    {

		    byte[] buffer = new byte[formatWidth]; // formatWidth = 4

		    while (dataStream.Position < dataStream.Length) // datastream.length = 4096

		    {

			    databox.Data.Read(buffer, 0, formatWidth);

			    dataStream.Write(buffer, 0, formatWidth);

		    }				    

	    }

eppo

4,879

June 16, 2012 08:39 PM

You have to write data per row/scanline as the driver may add extra padding at the end of each row.

e.g. for a single array slice:





for(int i = 0; i < 256; ++i) memcpy((byte*)databox.pData + databox.RowPitch * i, sysmem + 256 * 4 * i, 256 * 4);

Gavin Williams

986

Author

June 16, 2012 09:47 PM

Curious, is that a hangover or what ?

Here's my SlimDX version of your code :



for (int row = 0; row < height; row++)

{

	 byte[] buffer = new byte[width * formatWidth];

	 databox.Data.Seek(row * databox.RowPitch, System.IO.SeekOrigin.Begin);

	 databox.Data.Read(buffer, 0, width * formatWidth);

	 dataStream.Write(buffer, 0, width *formatWidth);

}

21st Century Moose

13,459

June 16, 2012 09:57 PM

This also happens in native D3D10/11. Some hardware/drivers will allocate a padded resource where others won't, and it's entirely down to how the hardware/driver decides to allocate the resource.

Direct3D has need of instancing, but we do not. We have plenty of glVertexAttrib calls.

MapSubresource() returning incorrectly sized databox ?

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MapSubresource() returning incorrectly sized databox ?

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