How to initialize an array inside a struct GLSL - glsl

Question

I'm try to initialize an array inside a struct, as follow:
struct myStruct {
vec3 data[20] = vec3[20] (vec3(1, 1, 1), vec3( 1, -1, 1), vec3(-1, -1, 1), vec3(-1, 1, 1),
vec3(1, 1, -1), vec3( 1, -1, -1), vec3(-1, -1, -1), vec3(-1, 1, -1),
vec3(1, 1, 0), vec3( 1, -1, 0), vec3(-1, -1, 0), vec3(-1, 1, 0),
vec3(1, 0, 1), vec3(-1, 0, 1), vec3( 1, 0, -1), vec3(-1, 0, -1),
vec3(0, 1, 1), vec3( 0, -1, 1), vec3( 0, -1, -1), vec3( 0, 1, -1));
};
But I get this error:
ERROR: 0:84: '=' : syntax error: syntax error
It is possible to do that?

Answer 1

struct starts a type specification and not a variable declaration. You have to declare a variable and to use a struct constructor (See Data Type (GLSL) - Struct constructors):
struct myStruct {
vec3 data[20];
};
myStruct myVar = myStruct( vec3[20]( vec3(1, 1, 1), ..... ) );
See GLSL Specification - 4.1.8 Structures
User-defined types can be created by aggregating other already defined types into a structure using the struct keyword. For example,
struct keyword. For example,
struct light {
float intensity;
vec3 position;
} lightVar;
Structures can be initialized at declaration time using constructors, as discussed in section 5.4.3 “Structure
Constructors”
See GLSL Specification - 5.4.3 Structure Constructors
Once a structure is defined, and its type is given a name, a constructor is available with the same name to
construct instances of that structure. For example:
struct light {
float intensity;
vec3 position;
};
light lightVar = light(3.0, vec3(1.0, 2.0, 3.0));