Hi,

I'm working through the Optimization Tutorial: Particles and High-Frequency Code sample.

I've made every change (I think) but I get the following error and can't figure out why or how to fix it - I'm very, very new to this :O)

Error 1 Errors compiling ... \SimpleScreen.fx:
.. \SimpleScreen.fx(33): error X3004: undeclared identifier 'AttractorPos' 

 

the error occurs in this line in the shader code:

float3 distV = attractorPos - In.ObjectPos;

 

 

even though earlier in the code, following the tutorial, i have entered:

struct VS_OUTPUT

{

float4 ScreenPos: POSITION;

float4 VertexColor: COLOR;

float3 attractorPos;

};

 

 

do you think it is an error in the shader code or the C#?

 

please help!

Thanks,

kingkatt

 

Since attractorPos is a member of the VS_OUTPUT structure, you need to qualify that variable reference in your code with a variable of type VS_OUTPUT. 

In the same line, you have In.ObjectPos.  This means get the variable named ObjectPos, which is a member of the structure type associated with the variable In.  You need to do the same thing with your attractorPos variable.  Somewhere in the same function you should have a variable of type VS_OUTPUT, let's say it is called Output.  Then, you would need Output.attractorPos.

If anyone is still looking for the answer to this the problem is caused by putting the line:
float3 attractorPos;

inside of struct VS_OUTPUT. like this:
struct VS_OUTPUT
{
    float3 attractorPos;
    float4 ScreenPos:   POSITION;
    float4 VertexColor: COLOR;
};

Solution:
It must remain outside like this:

struct VS_OUTPUT
{
    float4 ScreenPos:   POSITION;
    float4 VertexColor: COLOR;
};
float3 attractorPos;
float halfScreenWidth;
float halfScreenHeight;