SPRUI04F july 2015 – april 2023
You can specify the values to use for vector initialization or assignment using literals or scalar variables. When all of the components assigned to a vector are constants, the result is a vector literal. Otherwise, the vector's value is determined at run-time.
For example, the values assigned to vec_a and vec_b in the following declarations are vector literals and are known during compilation:
short4 vec_a = (short4)(1, 2, 3, 4);
float2 vec_b = (float2)(3.2, -2.3);The following statements initialize all elements of a vector to the same value, which is 1 in this case.
ushort4 myushort4 = (ushort4)(1);Shorter vectors can be concatenated together to form longer vectors. In the following example, two int variables are concatenated into an int2 variable. The value of myvec in the following function is not resolved until run-time:
void foo(int a, int b)
{
int2 myvec = (int2)(a, b);
...
}The following example concatenates two int2 variables into an int4 variable, which is passed to an external function:
extern void bar(int4 v4);
void foo(int a, int b)
{
int2 myv2_a = (int2)(a, 1);
int2 myv2_b = (int2)(b, 2);
int4 myv4 = (int4)(myv2_a, myv2_b);
bar(myv4);
}