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## Vectors

The Vector class is a toolkit of vector functions that is used by Mirage. They are accessed using the command Vector::<function_name>(a, b, c) e.g. Vector::sub(to, from, dir);

```  // Adds vectors a and b, stores the result in vector result
// which may be one of a or b.
static void add(vector a, vector b, vector result);

// Add a fraction of vector a to vector b.
//Stores result in b
static void addfrac(double frac, vector a, vector b);

// Subtracts vector b from vector a, stores the result in
// vector result which may be one of a or b.
static void sub(vector a, vector b, vector result);

// Calculates the scalar dot product of two vectors a and b
static double dot(vector a, vector b);

// Sets vector a to equal vector b.
static void set(vector a, vector b);

// Assigns the given values to the vector a.
static void assign(vector a, double xval, double yval,
double zval);

// Returns the magnitude of the vector a.
static double magnitude(vector a);

// Finds the minimum of two vectors on a value-by-value basis.
// ie.  result[X] = MIN(a[X], b[X]);
//      result[Y] = MIN(a[Y], b[Y]);
//      result[Z] = MIN(a[Z], b[Z]);
inline static void min(vector a, vector b, vector result);

// Finds the maximum of two vectors on a value-by-value basis.
inline static void max(vector a, vector b, vector result);

// Scales a vector a by the given scalar quantity s, stores
//result in vector result.
static void scale(double s, vector a, vector result);

// Normalises a vector.
// If the vector has length 0 this will cause an error.
// set msg to be a useful string which can locate where the error
// was caused when the error message is produced.
// Error Message:
// ``*** Divide by zero in <msg>, continuing...
static void normalise(vector v, char *msg);

// Cross product (a x b), stores result in result.
static void cross(vector a, vector b, vector result);

// Stretch a vector; same format as the object's stretch
// routine.
static void stretch(double x, double y, double z, vector v);

// Shift a vector; same format as the object's shift routine.
static void shift(double x, double y, double z, vector v);

// Rotate a vector; same format as the object's rotate routine.
static void rotate(axis from, axis to, double angle, vector v);

// Rotate a vector; same format as the object's rotate routine.
static void rotate(axis around, double angle, vector v);

// Rotate a vector; same format as the object's rotate routine.
static void rotate(vector given_fwd, vector given_up,
vector v);

// Shear a vector; same format as the object's shear routine.
static void shear(axis from, axis to, double amount, vector v);```

Sophie Day
Fri Feb 20 15:47:19 NZDT 1998