Reading pixel data

Hello,

I'm fairly new to C# and Mogre.

I'm trying to write a coverage map system for building static geometry, using a texture's alpha channel as density. I'm using this as a nudge in the right direction, but something's still not right.

unsafe public CoverageMap(string Texture)
{
TexturePtr tex = TextureManager.Singleton.GetByName(Texture);
if (tex != null)
{
Width = tex.Width;
Height = tex.Height;

// Lock the texture's pixel buffer
HardwarePixelBufferSharedPtr buffer = tex.GetBuffer();
buffer.Lock(HardwareBuffer.LockOptions.HBL_READ_ONLY);

// Allocate a new alpha buffer
AlphaBuffer = new Byte[Width * Height];

// Obtain a handle to the pixel buffer
PixelBox box = buffer.CurrentLock;
Byte* bytebuffer = (Byte*)box.data.ToPointer();

for (int j = 0; j < Height; j++)
{
for (int i = 0; i < Width; i++)
{
Byte r = bytebuffer[j * Width + i + 0];
Byte g = bytebuffer[j * Width + i + 1];
Byte b = bytebuffer[j * Width + i + 2];
Byte a = bytebuffer[j * Width + i + 3];
AlphaBuffer[j * Width + i] = a;
}
}

// Unlock the texture's pixel buffer
buffer.Unlock();
}
}


The pixel data is always read as 0 (zero). The source image is a 32 bit PNG.

What am I doing wrong?

Thanks,

first of all,you have to know which format does the Texture your reading from Has ( ex: RGBA,F16,F32) then to read the pixels in the given format of the Texture is,if it is RGBA ( you have to read 4 bytes,Red,Green,Blue,Alpha) if its F32( you have to read 4 floats)

hope it helps