guRotate
# guRotate [Function]

### Function

guRotate

*Creates a modeling matrix for rotation around an arbitrary axis (fixed point)*

### Syntax

```
#include <ultra64.h> /* gu.h */
void guRotate(Mtx *m, float a, float x, float y, float z);
```

### Arguments

**m**
- Pointer to the matrix resulting from the calculation
**a**
- Angle of rotation (in degrees) around an arbitrary axis
**x**
- x component of axis of rotation
**y**
- y component of axis of rotation
**z**
- z component of axis of rotation

### Returned value

None

### Description

Returns a modeling matrix to the structure indicated by **m** for use in rotating around the arbitrary axis represented by the line passing through the origin and a point (**x**, **y**, **z**) by an amount of **a** degrees in the positive direction. When this function is called, the result is the creation of the following kind of modeling matrix:

(* Note that the values (x,y,z) here are normalized inside the function)

For a detailed explanation about the fixed-point format, see gSPMatrix. Floating-point is handled using the guRotateF function.

### Note

The vector does not have to be normalized ahead of time. This is done inside the function. However, when = 0 the operation of this macro cannot be guaranteed. Also, note that an angle with a positive value represents counter-clockwise rotation.

### Comment

The Mtx structure looks like this:

```
typedef long Mtx_t[4][4];
typedef union {
Mtx_t m;
long long int force_structure_alignment;
} Mtx;
```

### See also

gSPMatrix, guAlign, guAlignF, guPosition, guPositionF, guRotateF, guRotateRPY, guRotateRPYF, guScale, guScaleF, guTranslate, and guTranslateF

### Revision history

03/01/99 Completely rewritten.