Some ACSUtils functions return multiple values (e.g. vector math functions, but also some non-math functions). ACS doesn't support returning multiple values from a function.

ACSUtils uses a convention to fake returning multiple values from a function. The convention is as follows: there are 8 global variables with names r1 through r8. If a function returns multiple values, it actually returns no value and writes the first “returned” value to r1, the second one to r2, and so on.

Here's an example, RotateVector returns X and Y:

RotateVector(x, y, angle);
int newX = r1;
int newY = r2;

SomeFunctionWithMultipleReturnValues(...);
SomeOtherFunction(r1);
int b = r2;

SomeFunctionWithMultipleReturnValues(...);
int a = r1;
int b = r2;

SomeOtherFunction(a);

But overwriting argument variables immediately after calling the function is valid:

RotateVector(x, y, angle);
x = r1;
y = r2;

An example of a function returning three values:

normalize3d(x, y, z);
int newX = r1;
int newY = r2;
int newZ = r3;