# Working with special effects

This section starts with some introductory information and then steps you through creating cels with special effects. You learn about:

- How PIXC and P-Mode works.
- How to make an entire cel translucent.
- How to enhance luminance.
- How to define a translucent area in an opaque cel.

## How PIXC and P-Mode works

Each cel has a PIXC; which determines some of the cels attributes. By default, cels are rendered as opaque, but you can change the PIXC to enhance luminance for the whole cel, create a ghost effect by mixing the entire cel with the background (making it translucent), or create a shadow.

Each cel actually allows for two PIXC settings, allowing you, in effect, to make some pixels in the cel translucent (one PIXC settings group) while all others remain opaque.

- For 8-bit coded cels-you can create special effects on a color-by-color basis. For example, you can enhance the luminance of all shades of red for the lights of a police car.

- For 6-bit coded and 16-bit uncoded cels-you can create special effects on a pixel-by-pixel basis. First you create a mask, then mix the cel pixels in the region of the mask with background pixels to create the desired special effect.

The two possible PICX settings a cel can choose from are often referred to as P-Modes.

### For more information

PIXC and P-Mode is explained in greater detail in Introduction to 3DO Graphics.

### About this section

This section steps you through the following examples of using special effects:

- How to make an entire cel translucent.
- How to enhance luminance.
- How to define a translucent area in an opaque cel.

## How to make an entire cel translucent

This section steps you through mixing background image pixels and cel pixels to create a ghostlike translucent effect.

To create a translucent cel, follow these steps:

1. Convert the source art to a 3DO cel of your choice.

2. If you wish, assign a background color to create an irregularly shaped cel.

3. In the Set 3DO Object Type dialog select the P-Mode box in the CCB Settings column.

   The P-Mode pop-up menu appears.

4. Select Make it 1 from the pop-up menu.

   This instructs the 3DO hardware to use the PIXC settings specified by P-Mode 1 for the whole cel.

   Note: P-Mode 1 and P-Mode 0 are just names that were chosen and do not imply that P-Mode is on or off.

5. From the 3DO Options menu, select Set CCB.

   The Load CCB Settings dialog appears.

6. Click the Translucency Options button.

   The Translucency Options dialog appears (see Figure 1).

   Figure 1: Translucency Options settings for 25 percent translucency.

7. Set up the Translucency Options dialog as follows (see Figure 1 above):

  - Click the P-Mode One button
  - From the P-Mode presets pop-up menu select Opacity 25%.
  - For the first source, click the Cel Data button.
  - For the second source, click the Frame Buffer button.
  - Leave the other options at their default settings.
  - Click OK to verify the settings.

All pixels in the cel that you want to be translucent-a ghost perhaps-will use the P-Mode One setting. The translucent effect is attained by appropriately mixing the image (frame buffer) pixels with the cel (cel data) pixels. Because of this, the second source must be defined as the frame buffer, not zero.

For more information on how the 3DO system hardware can manipulate image and cel data to create special effects, see Programming 3DO Graphics

## How to enhance luminance

This section explains how you can use per-color P-Mode for an enhanced luminance special effect.

### Basics of per-color P-Mode

With an 8-bit coded cel, you can set the P-Mode on a per-color basis. As a result, you can affect pixels of a selected color (or colors) in the cel. You can mix those pixels with the background image for translucency (stained glass effect), or use a multiplier differently to enhance luminance (lights) or reduce luminance (shadow). If you alternate a cel with enhanced luminance with one of regular luminance, you can create a flashing-light effect when the animation is displayed.

### How to enhance luminance of selected colors

To enhance the luminance of selected colors in a cel, follow these steps:

1. Convert source art to an 8-bit coded cel.

2. If you wish, assign a background color to create an irregularly shaped cel.

3. In the 3DO palette grid, shift-select the colors for which you want to enhance luminance.

4. Click the P-Mode box in the bottom left region of the Set 3DO Object Type dialog, then select Make it 1 from the pop-up menu to the right of the function buttons.

5. From the 3DO Options menu, select Set CCB.

   The Load CCB Settings dialog appears.

6. Click the Translucency Options button.

   The Translucency Options dialog appears.

   Figure 2: Translucency Options settings for enhancing luminance.

7. Set up the Translucency Options dialog as follows (see Figure 2):
   - Click P-Mode One.
   - For the first source, click Cel Data.
   - For the second source, click Frame Buffer.
   - In the Multiply by field, make sure CCB is selected, then choose 1 from the pop-up.
   - In the Divide by field, make sure CCB value is selected, then choose 4 from the pop-up.
8. Click OK to apply the setting.

Here's the effect of your settings: By default, the first source is multiplied by 8, then divided by 8. If you divide by 4 instead (and still multiply by 8), you in effect enhance the luminance. To further enhance luminance you can divide by 2. To darken the color for a shadow effect, divide by 16 for this option.

## How to define a translucent area in an opaque cel

If you are working with a 6-bit coded cel or a 16-bit uncoded cel, you have the option of using a per-pixel P-Mode. You can create a mask to mark the regions of the cel that you want to be translucent, then select P-Mode settings that will make all areas of the cel one P-Mode (for example, opaque) and all areas defined in the mask a different P-Mode (for example, translucent).

This makes it possible, for example, to mask a window to become translucent green, or to mask the eye of a creature for which you want to enhance luminance.

### Creating a translucent area

Creating a translucent area inside an opaque cel consists of two basic steps:

- Defining the mask
- Choosing the CCB settings

To create the mask, follow these steps:

1. Convert your source art to a 6-bit coded cel or a 16-bit uncoded cel.

   The cel type you choose depends on the number of colors in the source art and the memory you expect to have available: A 16-bit uncoded cel allows for thousands of colors but needs over twice the memory of a 6-bit coded cel.

2. From the Windows menu, choose Show Mask Panel.

3. Click the Keep Mask button on the dialog that appears.

   This provides the same mask on all the frames. Since you will define the translucent area using a mask, this setting must be in place.

   Figure 3: Mask panel.

4. From the 3DO Options menu, select Show P-Mode Control Panel.

   A draft page appears underneath the source art for P-Mode. When you first open the control panel, the is source art is on top, the P-Mode draft page underneath.

   Figure 4: P-Mode control panel.

5. Define the area of the cel that you want to be translucent. For example, you could select an area for a translucent window.

6. From the Goodies menu, select Mask, then choose Mask Selection Only from the submenu.

7. In the P-Mode control panel, click the Copy Mask in PMode button, then click the PMode on Top button.

   You should see the area you selected pasted in as a black mask. To verify you have masked the correct area, you can make the draft page transparent by clicking the Transparency button.

   To specify how to paint the selected area, change CCB settings as follows:

   1. From the 3DO Options menu, choose Set CCB.

      The Load CCB Settings dialog is displayed.

   2. In the Load CCB Settings dialog, click the Translucency Options button.

      The Translucency Options dialog appears.

      Figure 5: Translucency Options settings for 12.5 percent opacity.

   3. Set up the Translucency Options dialog as follows (see Figure 5 above):
     - Click the P-Mode One button.
     - From the P-Mode presets menu, select 12.5% opacity.
     - For the First Source, select Cel Data.
     - For the Second Source, select Frame Buffer.
     - Click OK.