Re: [Flightgear-devel] Sound vol/pitch transforms are like panelx/y/r transforms

[Julian Foad]

Erik Hofman wrote:

[EMAIL PROTECTED] wrote:

I think we have a bit of confusion over the meaning of "offset". I

...

But if you look at the following example:

<pitch>
 <property>/engines/engine/rpm</property>
 <factor>0.0012</factor>
</pitch>

[which is calculated as
  pitch = (property * factor) + offset
        = (rpm * 0.0012) + 1.0
]

You would have to change it to the following to achive the same with your proposed change

<pitch>
<property>/engines/engine/rpm</property>
<factor>1.0012</factor>
</pitch>

No. I am only suggesting changing the default value for the pitch offset, not the way it is used to calculate pitch which is and would still be

pitch = (property * factor) + offset

Therefore with my proposed change your first example would have to be changed to

<pitch>
<property>/engines/engine/rpm</property>
<factor>0.0012</factor>
<offset>1.0</offset>
</pitch>

This is a good example because it is exactly what made me start looking at this in the first place. I had the first example configured, with the existing sound manager, and when I revved the engine up and slowed it down it didn't sound right. That is because in that example the pitch is not proportional to RPM:

RPM Pitch (approx.)
0 1.0
400 1.5
800 2.0
1600 3.0

I want the pitch to be proportional to RPM: when the engine is firing twice as many times per second, the sound pitch is twice as high. If normal pitch (1.0) happens to correspond to 800 RPM, I want 2.0 at 1600 RPM, etc. Therefore I want pitch to be (RPM * 0.0012) approximately. This could be written

<pitch>
<property>/engines/engine/rpm</property>
<factor>0.0012</factor>
<offset>0.0</offset>
</pitch>

which does what I want regardless of whether the default offset is 1 or 0. So no problem there.

I certainly do not want to delete any feature that is currently being used. I am looking for ways to simplify the code and semantics while *keeping* all the useful features.

Personally I think it is very powerfull as it is,

Yes, I agree. I'm not trying to say it's bad or it isn't powerful enough. It is good and it is quite powerful.

it just takes some creativity to take advantage of all the possibilities.

- Julian


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