On 2/06/14 12:38 AM, Michel Lerenard wrote:
Hi,
i've been there a few weeks back, the thing to understand if that the
FrameBuffer and the Imf image will always work as if the data buffer
was covering the whole image. You can't restrict a Framebuffer to work
on a part of the image by, for example, giving it a size.
What you'll need to do to write one tile is to configure the
FrameBuffer with a pointer pointing to the address at which you buffer
would start if it was covering the whole image. The rest is all
pointer arithmetic.
Typically if you're willing to write a tile that covers the region
256/128 : 287/163 ( a 32*32 tile starting at 256/128 ), and your data
buffer contains data for the current tile only, call:
out.setFrameBuffer (mybuffer - 256 * 128 * pixelSize , pixelSize,
tileWidth * pixelSize);
where mybuffer is a char*, pixelSize gives the memory size of an item.
(char = 1, half= 2, float = 4)
Thanks Michel, now I understand why there is the subtraction going on.
Cheers
--
Nicholas Yue
Graphics - RenderMan, Visualization, OpenGL, HDF5
Custom Dev - C++ porting, OSX, Linux, Windows
http://au.linkedin.com/in/nicholasyue
https://vimeo.com/channels/naiadtools
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