hcornea
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Kevin,
The alpha channel is simply information.
How information is used is defined in the material section of the model.
You can (for example) regulate reflection on a solid surface using the alpha channel in the diffuse texture, instead of using it for transparency.
The material defines what property the alpha is used for.
In FS9, there are no enhanced parameters and it is simply assumed that alpha = transparent.
That is fine, except that in FSX since SP2, z-buffer testing is required to properly render transparency. This is the price you pay for drawcall batching across multiple objects. FS9 objects simply "wipe" all that is behind them (trees, cloud etc, which is what you see in the picture)
So, to properly render the object in FSX:
You need to tell it to use the alpha as transparency (Framebuffer Settings = Set Default Transparent)
You need to Ztest the alpha against other transparent / alpha in the view in the same line of sight (ray)
(Specifying what test to use and the test levels)
You usually also write the alpha into the Z-buffer (so it gets sorted against other things)
Alpha is simply an information channel in the texture, nothing more, and certainly nothing magical.
All the FSX extended settings are explained and outlined the FSX SDK, which might be worth another read.
The alpha channel is simply information.
How information is used is defined in the material section of the model.
You can (for example) regulate reflection on a solid surface using the alpha channel in the diffuse texture, instead of using it for transparency.
The material defines what property the alpha is used for.
In FS9, there are no enhanced parameters and it is simply assumed that alpha = transparent.
That is fine, except that in FSX since SP2, z-buffer testing is required to properly render transparency. This is the price you pay for drawcall batching across multiple objects. FS9 objects simply "wipe" all that is behind them (trees, cloud etc, which is what you see in the picture)
So, to properly render the object in FSX:
You need to tell it to use the alpha as transparency (Framebuffer Settings = Set Default Transparent)
You need to Ztest the alpha against other transparent / alpha in the view in the same line of sight (ray)
(Specifying what test to use and the test levels)
You usually also write the alpha into the Z-buffer (so it gets sorted against other things)
Alpha is simply an information channel in the texture, nothing more, and certainly nothing magical.
All the FSX extended settings are explained and outlined the FSX SDK, which might be worth another read.
Last edited:
