# The Cel Control Settings dialog

The Cel Control Settings dialog.

Note: The Cel Control Settings dialog is mostly useful for programmers.

### Make All Black Pixels Transparent (BGND)

Prevents the cel engine from drawing black pixels to the frame buffer.

### Make Cel Invisible from the Front (ACW)

Causes the pixel projector to ignore pixels that are in portions of the cel that are not reversed. Part of a cel can be reversed as a result of manipulations of the pixel projector.

### Make Cel Invisible from Behind (ACCW)

Causes the pixel projector to ignore pixels that are in portions of the cel that are reversed. Part of a cel can be reversed as a result of manipulations of the pixel projector.

### Replicate LSBs in RGB 8-bit Cel (Rep 8)

Applies in the cel engine when an 8-bit uncoded cel is expanded to a 5-5-5 RGB value. The red and green components need another two bits, and the blue component needs three bits. If this option is checked, the extra bits are duplicated from the low bits of each component. Otherwise, the component values are padded with zeros.

### XOR the Two Data Sources (PXOR)

Causes every pixel in the cel to Exclusive-OR (XOR) on top of a frame buffer pixel. Animations benefit from having frames XORed to eliminate redundant portions of consecutive frames. When the XORed frames are packed, they take up much less room. The 3DO Animator tool can produce XORed 3DO animations.

### Pack Cel Data

Causes the cel data to be packed using a run-length encoding scheme. The packed data is unpacked inside the cel engine.

### Turn Off Pixel Interpolation (MARIA)

Disables the region fill operation in the cel engine. As a result, every pixel in the source image will map to at most one pixel in the destination area. If the cel is scaled 1:1 or smaller, the cel will look normal. If the cel is scaled larger than 1:1, the effect will be a sparse array of pixels suitable for certain types of explosion effects and other special effects. The MARIA bit has nothing at all to do with interpolation.

### Enable Cel Super Clipping (ACSC)

Turns on cel clipping. If a cel will never be able to make it back to the display, rendering is abandoned. Checking this option currently has no effect.

### Enable Line Super Clipping (ALSC)

If super clipping (ACSC) is turned on, this option turns on line clipping. If line clipping is on and a given line will never move back onto the display (or never make it there at all), the cel engine terminates processing of that line and the next line is started. Checking this option currently has no effect.

### Put Preamble Words in Data (CCBPRE)

The preamble words are by default stored in the cel control block (CCB). If you check this option, they are also stored at the beginning of the cel data. This is useful if you are working on an animation with different frame sizes, since the hardware won't have to search the CCB for the size information. In other cases, this option can be left off.

### Enable Second Corner Engine (ACE)

Enables the second corner engine. Ideally, this processes the cels to the frame buffer at twice the speed of one corner engine. The effect of this is to speed up the rendering process, and so it should be generally enabled.

### Lock Corner Engines Together (LCE)

The Lock Corner Engines (LCE) flag forces the two corner engines to process source pixels at the same rate. Both the SCE and LCE flags are required to be true for LRFORM cels, but software does not need to set the bits in the case of LRFORM cels because the hardware sets the flags internally.

At certain times it might be useful to lock the corner engines together to allow for a more predictable path through the rendering process (normally the engines operate asynchronously), but it is in general not necessary and does impact rendering performance slightly.

### Terminate Cel if Wrong Direction (TWD)

Causes the cel engine to stop processing when the first backward pixel is encountered.