TYPE: COP
TITLE: Layer COP

This operation does a composite (over, under, inside, add, etc) between up to
eight images. The first image is always the background image, and subsequent
images are layered in order. The size of the resulting image is the size of
the background image.

In the case of an over, the result image is 

4 over (3 over (2 over 1))

for four inputs, 1 to 4.

The Composite COP provides a more traditional A over B method of compositing.

Parameters
Composite
    Operation        - Specifies the global compositing operation:
	Over     - Places the foreground over the background.
	Under    - Places the foreground under the background's alpha.
	Atop     - Places the foreground over the background only where
		   the background alpha exists.
	Inside   - Places the foreground inside the background's alpha.
	Outside  - Places the foreground outside the background's alpha.
	Screen   - Inverts both, multiplies, inverts the product.
	Add      - Adds the foreground to the background.
	Subtract - Subtracts the foreground from the background.
	Diff     - Takes the absolute difference between the foreground
		   and the background.
	Multiply - Multiplies the background by the foreground.
	Minimum  - Takes the minimum of the foreground and background.
	Maximum  - Takes the maximum of the foreground and background.
	Average  - Takes the average of the foreground and background.
    Image Units        - Selects pixels or UV units for the transforms.
    Image Filter       - Specifies the filter to use when transforming.
    Motion Blur        - Toggles on motion blur, and specifies the time range
                          around the current frame to blur.
    Motion Frame Bias  - Shifts the time range for the blur.
    Motion Blur Segments - Number of samples to blur together in the specified
                           time range.
    Motion Blur Method - 
        Velocity    - Only uses the current frame and the transform to compute
                      past and future positions.
        Deformation - Cooks the images at all time samples.

Transform (1 set per foreground input)
    Operation          - Specifies the composite operation for this input,
			 and how this input wraps when outside its image 
			 bounds (repeat, clamp, decal, mirror). The default
			 compositing operation is "global" which uses the
			 operation specified on the Composite page.
    Translate, Rotate, Scale, Pivot - Transforms this foreground in X,Y relative
                                      to the background.

Merge
    Overview - These parameters specify how to build the output sequence when
	       there are differences between the input sequences. See the
	       Composite COP for more details.

Local Variables:
    L   - Sequence length
    S   - Start of sequence
    E   - End of sequence
    IL  - Input sequence length
    SR  - Sequence frame rate
    NP  - Number of planes in sequence
    W,H - Width and height of image
    I   - Image index (0 at start frame)
    IT  - Image time (0 at start frame)
    AI  - Current plane array index
    PI  - Current plane index
    PC  - Num of channels in current plane

See Also: Composite
