I work hexagon maps, and I store everything with ivec3 because most operations are cheaper with integers. It's common for when calculating from hexagon space to world/screen space, convert the ivec3 to vec3, so there's no rounding issues. It would be nice to have ivec types to vec type conversions. Something like:

void vec3_ivec3(vec3 const a, ivec3 dest)
{
	dest[0] = a[0];
	dest[1] = a[1];
	dest[2] = a[2];
}

void vec2_ivec2(vec2 const a, ivec2 dest)
{
	dest[0] = a[0];
	dest[1] = a[1];
}

Maybe a macro?

#define vec3_ivec3(a) ((ivec3) { a[0], a[1], a[2] })

ivec3 dest = vec3_ivec3(a);

any better ideas? feedback welcome.