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FX Composer - Passing Annotations into Array

Started by steviedisco Aug 24, 2011 at 3:09 PM 0 replies 1.7k views

Original Post

Aug 24, 2011 at 3:09 PM

Hi,

I'm currently learning shaders and have gone through all the basics (diffuse, specular lighting etc). The examples that I have read have referred to a one-light system.

Within FX Composer, you can tie lights to variables via the use of annotations and semantics. I've extended my base shader to two lights, but that is hard-coded. For instance:


 float4 LightDirection1 : DIRECTION <
 string Object = "Light0";
 string UIName = "Light Direction 1"; 
 string Space = "World";
 > = {-0.5f, 2.0f, 1.25f, 1.0};
 
 float4 LightDirection2 : DIRECTION <
 string Object = "Light1";
 string UIName = "Light Direction 2"; 
 string Space = "World";
 > = {0.5f, 1.0f, 0.5f, 1.0};

I'm trying to set up a more general case for an abitrary number of lights, say 3. I'd rather have an array of light structs like so:


 struct Light
 {
 float4 Position : POSITION;
 float4 Direction : DIRECTION;
 float4 Color : COLOR;
 };
 
 Light Lights[3];

Any idea how to tie FX Composer's light objects to this via annotations? I can't seem to get it to work, I've made all sorts of attempts, but nothing will compile.

Do I need to do this via scripting or am I missing something simple? I think I know how to do this if I was connecting into my DirectX app, but I'm trying to keep it all within FX Composer while I develop.

Help a brother! Many thanks.

steviedisco

Author

steviedisco

Aug 25, 2011 at 12:43 PM

I got closer, but I think by the looks of what I have read I am trying to achieve the impossible, as far fetched as that might seem.

It appears that it *should* be possible like follows:


 float3 LightPositions[MAXLIGHTS] : POSITION
 <
 string SasBindAddress = "Sas.Light<li>.Position";
 >;
 
 float3 LightDirections[MAXLIGHTS] : DIRECTION
 <
 string SasBindAddress = "Sas.Light<li>.Direction";
 >;
 
 float4 LightColors[MAXLIGHTS] : COLOR
 <
 string SasBindAddress = "Sas.Light<li>.Color";
 >;

but either FX Composer doesn't support that method of SAS Binding or it used to and now doesn't. I can't seem to find any concrete information on this, just bits and pieces on forums which seem years old.

I can't be the only one wanting to do this can I?

I can work around it I think, just set a limit on the number of lights (say, 3) and hard-code the bindings in, but it would have been nice to have this all wrapped up in a neat little package.

To be honest, I'm not working toward a particular goal (ie, plugging into an engine), I'm just playing and expanding on what I've learnt so I can build up a good knowledge of shaders and in particular how FX Composer works. I could always take it right out of FX Composer and run it through a C++ app, in which case I could easily get it to work, but it would have been nice to get it all tied up in one environment.

oh well

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