| Common Production Tasks
| The Power Game Factory interface relies heavily on a few types of controls that are not seen frequently in other Mac OS applications. The usage of each of these controls is described below.
| Using Image Wells
| The pictures used by a game project's various animation sequences and interface elements are displayed in image wells. Moving a picture into an image well adds it to a game project. Image wells that contain sprite animation frames come in pairs, as shown above. The first well contains a color image, with pure white pixels (RGB value 255,255,255) representing the empty space surrounding the sprite. The second well contains a mask, which is a grayscale picture of the same dimensions as the image itself, used to determine the opacity of each pixel in a given frame. Any white pixels in a mask indicate full opacity, and darker colors represent varying levels of transparency, with black (RGB value 0,0,0) indicating complete transparency. Be sure to create images and masks that follow these specifications to ensure that they appear correctly in Power Game Factory and, more importantly, in the game itself. A button labeled Generate Mask appears near the Mask image well, and may be used to quickly create a simple mask for the associated image. When this button is clicked, all of the image's background pixels are fully masked out, and all of the image's foreground pixels are assigned full opacity. More refined masks featuring soft edges and varying levels of transparency can not be created with the Generate Mask button; such masks must be painted in the Image Editing Window or created in a third party image editing application and moved to the mask image well by hand. More information on the Image Editing Window is available in the Using the Image Editing Window section. Most image wells contain images that are part of multi-frame animation sequences, much like the one shown above. In cases like these, an accompanying list box contains all of the images in the animation sequence, and whichever frame is selected in the list box is displayed in the image well. Before moving a picture into this type of image well, the animation frame that is to be updated must be selected in the list box. To quickly change the selection from one frame to another, use the up and down arrow keys. (This is a good way to preview an animation sequence when you want to make sure it is fluid.) The Add Frame button appends a new frame to the end of the animation sequence, and the Remove Frame button can be used to delete the selected frame. Animation sequences may be nearly any length. An image well's picture can be easily modified using Power Game Factory's built in image editing features. To modify an image, simply double-click it, or command-click it and select "Edit Image..." from the contextual menu that appears. Power Game Factory's Image Editing Window features many of the same tools and editing modes commonly found in sophisticated painting programs. More information on the Image Editing Window is available in the Using the Image Editing Window section. Although the Image Editing Window is often the quickest way to modify the appearance of a game object, third party painting programs are fully supported. Any pictures created in a seperate applications must be manually moved into an image well. There are three ways to do this. The first is to drag an image file from the Finder into the well. Pictures may also be dragged directly from some image editing applications. If an image is dragged into a well from the Finder, it must be in one of the following image file formats:
Image File Format Name | File Name Extension
BMP | .bmp
GIF | .gif
JPEG | .jpg*
PICT | .pct
PNG (Portable Network Graphics) | .png
Photoshop | .psd
Targa | .tga
TIFF (Tagged Imager File Format) | .tif**
* | The JPEG file formal utilizes lossy compression, which reduces image quality. It is best used for large, low-definition level background images that would otherwise require excessive disk space.
** | When saving TIFF files, set the Image Compression to either None or LZW. Power Game Factory does not support other TIFF compression types, such as ZIP and JPEG.
The second way to move a picture to an image well is to copy the image in an image editing application and paste it into the well. control-click the well and select Paste Image from the contextual menu that appears. A third way to move a picture to an image well only applies to image wells that display animation sequence frames. Select a frame from the nearby animation frames list box and choose Paste from the Edit menu. Images must be created with a resolution of 72 pixels per inch. It is best start with a color depth of 24 bits per pixel, as images are automatically converted to 24 bits per pixel when they are added to game projects. For relatively small images such as character animation frames and animated scenery, it does not matter which format the image is stored in prior to importation into Power Game Factory. These images are always converted into the PICT format, which can be loaded very quickly compared to the other file formats. One limitation of the PICT file format, however, is that an image may not exceed 4095 pixels in height or width. As a result, large level background images are not able to be converted to the PICT format when they are imported. The TIFF and PNG formats are reasonable alternatives, since they are not constrained by size limitations and load reasonably quickly (though not as quickly as PICT.) Unless disk space is a concern, the JPEG format should generally be avoided due to its use of lossy compression. A list of recommended image editing applications capable of saving images in all of these formats can be found in the Content Creation Applications section.
| Object Type Management
| A common set of controls is used to manage various game object types, such as character types, projectile types, and contrail types. On the left of each object type editing window is a list box containing the names of each object type. Below the list box are controls for renaming the selected object type, deleting the selected object type, and creating a new object type. The various editable properties of the selected object type appear to the right of the object type management controls. When a new object type is created, a dialog box appears presenting three object type creation options, as shown below. The new object type may be based on the currently selected object type, or it may be imported from the Content Library or from the disk. If the first option is chosen, the new object will be completely identical to the selected object. The word "Copy" will be appened to the new object's name so that it can be differentiated from the existing object. If the second option is chosen, the Content Library Window will appear, as shown below. This window contains a list of all the objects of a given type within the Content Library. To import one of these objects into your game project, simply select its name and click the Add to Game Project button. For additional options, click the Content Library Manager... button. The Content Library Manager is used to add and remove objects from the Content Library. More details are available in the Using the Content Library section.
| Editing Property Lists
| Some object types, particularly character types, have large numbers of properties that are arranged into property lists such as the one shown above. Property lists contain several rows, with property names usually appearing in alphabetical order in the left column, and with their values listed in the right column. Most property values are numbers, but some are checkboxes that may be checked or unchecked.
| Editing Sound Collections
| Most of the sound effects used by characters, weapons, projectiles, and other objects in a game are collected into sets of several sounds, only one of which is actually heard each time the sound is played. In an effort to prevent game audio from becoming repetitive, the exact sound that is heard is chosen at random. In Power Game Factory, list boxes contain each variation of a sound. Sound collections are managed with the nearby Remove Sound and Add New Sound buttons. To preview a sound, select it and click the Play Sound button. Sounds may be stopped by pressing Command-. (Command-Period) on the keyboard. When adding new sounds, the Open dialog box appears, prompting you to select a sound file. Power Game Factory supports sounds in the formats listed in the chart below.
Sound File Format Considerations | The System 7 Sound format is generally recommended for game audio content, because a sound in the System 7 format can be loaded considerably more quickly than an equivalent sound file in a different format. The System 7 Sound format has a unique drawback, however: it does not benefit from the Power Game Factory compiler's ability to merge duplicate sounds. Therefore, if a number of object types all share the same sound (for example, multiple weapons producing the same firing sound), and if memory and disk space requirements are of more importance than loading times, duplicate sounds should be stored in a different format, such as AIFF or WAV. Very large sounds files and sound files that use sophisticated compression techniques, such as MP3, are not recommended, because they take longer to load.
Sound File Format Name | File Name Extension | Loading Time (Seconds)*
Audio Interchange File Format | .aiff | 1.45
MPEG Layer 3 | .mp3 | 2.75
System 7 Sound (Recommended) | .sfil | 0.11
WAVE | .wav | 1.45
* | Values indicate how long it took to load a 23 second 16 bit 44.1 kHz sound into a game on a Power Macintosh G5/1.8 GHz. Shorter times are better.
Note that MP3 sound files use lossy compression. Although this type of compression results in decreased disk space requirements, memory requirements and loading times are not positively affected. The use of MP3 files is recommended only if disk space is of more importance than all other considerations. The Content Creation Applications section provides information on various audio editing applications that can be used to create sounds for games.