# adding a plane surface as an obstruction

(GhPGame) #1

Hi,

I’m using the addpolygon method to add a plane as an obstruction for a sound source. I’m just feeding 4 vertices and adding one quad polygon (assuming that the sound source is blocked by a wall).
I believe that even if I set the direct factor to 1.0f I should still hear something because of the leakages of the margins of the wall but I don’t. Is this a true assumption or FMOD assumes that the sound will totally be absorbed by the wall.
Thank you.

(Brett Paterson) #2

yes there is no ‘leakage’. It is simply a line in poly test and does not do radiosity or any multi-bounce logic. That is what reverb is for. You can set a direct and reverb material absorption level to simulate it.

(GhPGame) #3

You mean if I set the direct factor to something less than 1 and the reverb factor to something more than zero, when the listener is standing in front of the plane, he will hear the effect of both reverb and absorption. Right?

(Brett Paterson) #4

Unless a wall is really really thick and solid, I would probably have it lower than 1 and use frequency filtering (ie FMOD_INIT_CHANNEL_LOWPASS) so you get a good low frequency effect getting through walls. Depending on the shape of the object, if the reverb was 0 you would hear the reverb of the sound clearly through the wall, which is a fake way to simulate it bouncing around the edges of the wall. Tweaking it, for example setting it to 0.5 might make it more realistic, but it needs hand tuning.

(GhPGame) #5

So you mean even if I set the direct to something lower than 1 and set the reverb to 0, I still hear the reverb of the sound and that is a way to simulate bouncing around the edges of the wall. Right?

(Brett Paterson) #6

Hi, yes, I would check http://ixbtlabs.com/articles2/sound-technology/ down at the ‘occlusion’ section, it shows the different ideas regarding this, 1. obstruction, 2. occlusion, 3. exclusion.

(GhPGame) #7

Thank you so much Brett.