A sprite with an added mask will look like this:
JustBasic requires a sprite mask to make areas of a bitmap image transparent when displayed.
From the JustBasic help manual (JustBASICHelp.chm) under 'Sprite Table of Contents' - 'Add a Mask' it shows this:
A sprite starts with a drawn image that has a black background, like this:
A sprite with an added mask will look like this:
(Alien Ship Image from: Kenny's Free Assets )
Fast Sprite Maker makes creating the masked image required by JustBasic, as quickly and easily, as possible.
If you specifically require a lower color bit depth for the masked sprite, use this program to mask a 24-bit bitmap. Open the masked sprite created by this program in MS-Paint and save the 24-bit masked sprite at a lower bit depth.
1) To get started find a bitmap image that you want use as a sprite. Press the 'Load Bitmap' button and select the file to be masked. A notification box will let you know that the bitmap image has been loaded.
2) Press the 'Make Sprite' button. It will take from just a
few milliseconds to several seconds to process, depending on the size of the original bitmap image.
3) After the original bitmap has been masked, a File Dialog will pop up,
type in the name of the newly created masked sprite. Just make sure you use a name
that is unique, otherwise Fast Sprite Maker will tell you that the name you chose
already exists in the current folder.
The masked sprite is read from disk,
and is centered horizontally when displayed on the screen. Don't worry if you can't see
all of a large sprite, it's a complete image on your hard drive.
The elapsed time taken to make a masked sprite from the original bitmap is shown below the 'Help' button.
The most important time saveing concept used is to make all changes in memory. All that's needed once the bitmap is loaded into memory is to create the masked portion of the masked sprite and never write any pixel to the screen.
In a nutshell this program reads the original bitmap into an array in memory then it simply checks the array of memory for a black pixel value. If it's a black pixel, write a white pixel to the sprite mask memory array, otherwise write a black pixel to the sprite mask memory array.
After all of the original bitmap memory array has been scanned, the sprite mask is nearly ready to be written to disk. Lastly, the original bitmap is appended to masked portion with out any changes.
Voila! The completed masked sprite is done!
The sprite has been made in it's entirety, and saved to disk when you named the output file. You don't always see the large mask + sprite on screen because there's not enough screen space to show the masked sprite completly. If you want to see the entire mask sprite in one go, use a graphic program that will automatically scale the sprite image to fit your view screen. (Paint.Net will automatically scale a loaded image to fit your screen.)
For an image of 122 x 122 pixels, it takes about 160 milliseconds to create the masked sprite.
For an image of 256 x 256 pixels, it takes about 650 milliseconds to create the masked sprite.
For an image of 512 x 512 pixels, it takes about 2.7 seconds to create the masked sprite.
For an image of 1024 x 1024 pixels, it takes about 7 seconds to create the masked sprite.
For an image of 2048 x 2048 pixels, it takes about 30 seconds to create the masked sprite.
For an image of 4096 x 4096 pixels, it takes about 120 seconds to create the masked sprite.
All of the above timings are based on my laptop computer. If you have a faster computer, it will take less time. Conversely, a slower computer will take a little more time.
The hard coded limit is 65536 x 65536 pixels for the final masked image but, JB may not be able to allocate a contiguous block of memory to process such a large bitmap file. Stick to images of 4096 x 4096 pixels or less for the masked sprite image, and everything should work just fine.