STRUCTURES AND ARRAYS

Structure

struct matStruct {
vec4 ambientColor; 
vec4 diffuseColor;
vec4 specularColor;
float specularExponent;
} newMaterial;

newMaterial = matStruct(vec4(0.1, 0.1, 0.1, 1.0),
                        vec4(1.0, 0.0, 0.0, 1.0),
                        vec4(0.7, 0.7, 0.7, 1.0),
                        50.0);

The data type struct is used to declare custom data structures based on standard types. A constructor for the structure with the same name is created automatically. The declaration of a variable (in this case "newMaterial") is optional.

Side note: There has to be an exact correspondence of the arguments of the constructor and the elements of the structure.

vec4 ambientColor = newMaterial.ambientColor; 
vec4 diffuseColor = newMaterial.diffuseColor;
vec4 specularColor = newMaterial.specularColor;
float specularExponent = newMaterial.specularExponent;

The elements of a structure can be accessed using the dot-operator.

Array

int newIntArray[9];
vec3 newVec3Array[3];

The data type array is used to declare custom arrays based on standard types. The following restrictions apply for arrays:

• An array can contain all basic data types as well as structures.
• An array can not be initialized at the time when it is declared.
• The elements of an array have to be initialized one after the other.

The elements of an array are initialized and accessed using the index of the respective element:

newIntArray[0] = 5;
newVec3Array[1] = vec3(1.0, 1.0, 1.0);

int newInt = newIntArray[0];
vec3 newVec3 = newVec3Array[1];

Side note: On iOS devices the elements of an array can not be accessed using a variable index, i.e. the value of the index has to be a compile time constant.