#include <stdio.h>

struct Vec {
    float x, y, z;
    float u, v;
};

void init_z(struct Vec *v, float z);

int main() {
    struct Vec v;
    init_z(&v, 1.1f);
    printf("z value is: %g\n", v.z);
    return 0;
}

void init_z(struct Vec *v, float z) {
    *v = (struct Vec){
        .x = 0.0f,
        .y = 0.0f,
        .z = z,
        .u = 0.0f,
        .v = 1.0f};
}