mi_eval_color in struct problem

[haggi]

I try to evaluate the color from a struct array and I'm failing.

My struct looks like this:


declare shader
color "megaTex" (
integer "randomSeed" default 1234, #:shortname randomseed
#array color "cols", #:shortname cols
array struct "Textures" {
integer "count" default 10, #:shortname count
color "color" default .0 .5 1.0 1.0, #:shortname color
scalar "minScale" default 0.5, #:shortname minscale
scalar "maxScale" default 2.0, #:shortname maxscale
scalar "maxRot" default 180.0 #:shortname maxrot
}
)
version 1
apply texture
end declare

Now I try to evaluate the color in the "Textures" struct as follows:


int i_obj = *mi_eval_integer(&paras->i_obj);
int n_obj = *mi_eval_integer(&paras->n_obj);
texStruct *ts = (texStruct *)mi_eval(state, &paras->texStructures) + i_obj;

for( int i = 0; i < n_obj; i++)
{
texStruct tStruct = ts[i];
mi_info("struct %d tcount %d scalemin %f scalemax %f", i, tStruct.count, tStruct.minScale, tStruct.maxScale ); //<- this is printed correct so I suppose I access the structure correctly
miColor micol = *mi_eval_color( &tStruct.color );
*result = micol;
mi_info("Eval col %f %f %f", micol.r, micol.g, micol.b);
}

return miTRUE;


This works if I use only a color. But as soon as I try to connect a texture to the "color" entry, I get a black color only.
If I use a simple color array instead of a structure array, the texture is evaluated without any problems.

I suppose there is something wrong in my code.

Would be great if anyone has an idea how I can solve the problem.

Update:

After a suggestion of bart, I tried the following:


for( int i = 0; i < n_obj; i++)
{
texStruct tStruct = paras->texStructures[ i + i_obj ];
miColor micol = *mi_eval_color( &tStruct.color );
}


This leads to an error:

DB 0.2 fatal 041052: accessing unknown tag 0x1

An access like this:


for( int i = 0; i < n_obj; i++)
{
texStruct tStruct = paras->texStructures[ i + i_obj ];
miColor micol = *mi_eval_color( &paras->texStructures[ i + i_obj ].color );
}


does not produce an error but the result is always black (0,0,0).

This only happens for the evaluation of the color. I can access the other values without problems, well... I dont evaluate them with a mi_eval.. command, this may be the reason why it works.

edit: I tried to evaluate the other struct values and they work without problems in any case.

[bart]

Can we see your two structs in the C code?
One for the struct in the array, and one for the struct passed as params containing it?

Can you print the pointers you get for tStruct and tStruct.color?

[haggi]

mi file:


declare shader
color "megaTex" (
integer "randomSeed" default 1234, #: shortname randomseed
color "baseColor", #: shortname basecolor
array color "colors", #: shortname colors
array struct "Textures" {
integer "count" default 10, #: shortname count
color "color" default .0 .5 1.0 1.0, #: shortname color
scalar "minScale" default 0.2, #: shortname minscale
scalar "maxScale" default 0.3, #: shortname maxscale
scalar "maxRot" default 120.0, #: shortname maxrot
integer "blendType" default 0, #: shortname blendType
scalar "blendMin" default .8, #: shortname blendMin
scalar "blendMax" default 1.0 #: shortname blendMax

} #: shortname textureList
)
version 1
apply texture
end declare



c structure:




struct texStruct{
int count;
miColor color;
miScalar minScale;
miScalar maxScale;
miScalar maxRot;
miInteger blendType;
miScalar blendMin;
miScalar blendMax;
};

struct megaTex_paras{
int randomSeed;
miColor baseColor;

int i_col;
int n_col;
miColor colors[1];

int i_obj;
int n_obj;
texStruct texStructures[1];
};



Addresses:
tStruct : 334473852
tStruct.color: 334473856

[bart]

For testing and debugging purposes, could you temporarily remove the color array?

Not sure this matters, but just to be certain in your texStruct try
miInteger count

Again, then take a look at what the pointers for the struct end the color end up being before the eval.

[bart]

oops, something just rang a bell in my recollection.

Currently, defaults are not supported for input parameters inside of structs.
What happens if you remove the defaults declared inside the struct?

[haggi]

No difference at all.
I still get a

fatal 041061: invalid tag value 0xad1f4b8 requested

with the access via


texStruct tStruct = paras->texStructures[ i + i_obj ];
miColor micol = *mi_eval_color( &tStruct.color );

[bart]

So what is the tag at tStruct.color? Can you print that before the mi_eval_color?
And then use the query codes to identify what it is.

Did you remove the color array, in case that was making a problem with the offset, or is it still ok if a static (non-shader) color is connected to the input?

[haggi]

Thanks to Halfdan Ingvarsson it works now.

Instead of trying to copy the struct with this:



texStruct tStruct = paras->texStructures[ i + i_obj ];
miColor micol = *mi_eval_color( &tStruct.color );


he suggested to use a pointer.



texStruct *tStruct = &paras->texStructures[ i + i_obj ];
miColor micol = *mi_eval_color( &tStruct->color );


What works because mr needs the complete structure instead of a copy to evaluate the correct offset data. Great, thanks to all!