## rotation around x axis

Like all linear transformations that command is in 2 modes:
direct and matrix.

## rotx obj

### rotx(an)obj(id)

Rotates the object **id** angle **an** around x axis versus
its center of gravity.
### rotx(an) vertex(s) obj(id)

Rotates vertices **s** of the object **id** angle **an** around x axis
versus its center of gravity.
### rotx(an) poi(x,y,z) obj(id)

Rotates the object **id** angle **an** around tth x axis versus point **(x,y,z)**.

**Note:**

objt is **fog, light, var, vol, view**.

**Exeamples:**

`rotx(PI/2) poi(100,-20,50) vertex[1,5] vol(1,3);`

x rotates vertices
(1,2,3,4,5) of volumes 1 et 3 angle PI/2around point (100,-20,50).

`rotx(PI/2) var("x");`

x rotates variable **x** angle PI/2
around its center of gravity.

`rotx(.1*PI) eye view(1);`

angle .1*PI around x axis the eys of the view 1.
### rotx(a1,a2)vol(a)rotx(b1,b2)vol(b)

Varies **rotx matrix vol(a)** in the interval **[a1,a2]** when
**rotx matrix vol(b)** varies in the interval **[b1,b2]**.

May be used to attach **rotx** variations
of volume **a** to those of its father **b**.

**Note:** **rotx(b1,b2)** can be any other transformation **transf(b1,b2)**.
## rotx image

### rotx(an) image(id)

Makes identic first column and last column of the image **id**.

**Notes:**

1) **an** is ethe portion of the image (between 0 and PI) affected by this operation.

2) Blur appears in this portion.

3) Useful for mapping an image on a closed surface in x.

4) If identifier **id** is absent, the current image by default.

**Example:**

`rotx(.1*PI) image(1);`

makes periodic the image by changing one tenth of its surface.
## rotx matrix

### rotx matrix vol(id)

Returns the angle of rotation about x of the matrix of the volume **id**.

**Options:**

**format(f)**: modulo **f**.
### rotx(a)matrix vol(id)

Rotates angle **a** around x the volume **id** by changing its matrix.

**Options:**

**ini**: the transformation is the basic.
## rotx view

### rotx(an)eye view(id)

Rotates the eye of the view **id** angle **an** around x axis.
### rotx(an)aim view(id)

Rotates the aim point of the view **id** angle **an** around x axis.

**Options:**

**validate(0)**: rotationfrom the initial position.
## See also: