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heureka
01-19-2007, 03:25 AM
Hi,

Earlier I questioned in this forum how to compute the graphics for a 2D-spectrogram most efficiently

http://www.opengl.org/discussion_boards/ubb/ultimatebb.php?ubb=get_topic;f=2;t=020999

Now I would like to display the spectrogram in 3D so that the audio input is drawn as a moving landscape (in the frequency domain that is); intially in a grid/wire fashion(guess
thousands of people have done this before). So my question is how to do the best way in terms of computational complexity.

The FFT procesing I already have running - so now I have to take care of the drawing.

Initially I thought that maybe I should draw the whole 3D landscape for every arriving FFT frame, but then I thought
that it could be done similar to the spectrogram problem (which was solved by applying an texture offset to the time direction such that it could imitate a circular buffer)


Is it therefore possible to allow the offset in the time direction to increase in infinite time so that I only have to draw the lines from the last FFT frame. What will happen when
the offset variable wraps around- can I control this somehow?

How I'm making myself clear

Thomas :)

zeoverlord
01-19-2007, 06:41 AM
Yes it's possible to do that, just reduce the offset value by 1 each time the offset is larger than 1.
it really doesn't matter since the texture coordinates are clamped between 0 and 1, anything above or below that causes it to repeat the texture if the textures wrap parameter is set up in that way (this is the default behaviour).

heureka
01-19-2007, 07:30 AM
Thanks a lot for your reply!

Cheers
Thomas