GameMaker Studio 2 has support for non-bitmap sprites in the form of vector SWF files or Spine Skeletal Animation files. Both these formats have their pros and cons, and the two sections below explain how to import them into the Sprite Editor as well as a bit of information about how they are rendered.
GameMaker Studio 2 has limited support for vector sprites. Generally all sprites in GameMaker use bitmaps which, while flexible in terms of content, place limitations on both the size and number of frames possible in a sprite before memory usage can become prohibitive. Vector sprites work around these limitations by storing and drawing their contents differently - instead of a grid of pixels, which can become blocky or fuzzy when scaled, they are drawn as triangles which can be scaled up without losing definition, as illustrated in the image below:
To help you visualise how this is done, the image below is of the same vector Fireman sprite only now we can see the polygons that are used to make the image within GameMaker Studio 2:
However, nothing is ever for free when it comes to programming games, and the tradeoff here with vector sprites is that they are more expensive to draw than bitmap sprites and this speed difference increases as the complexity of the animation being imported increases. Also, their memory usage is affected by their visual complexity, unlike bitmap sprites. Baring that in mind, they do make it possible to add large animated graphics in ways that would be impossible using traditional bitmapped sprites.
On the flipside of the performance equation, because vector sprites only draw the pixels absolutely required (unlike bitmap sprites which also "draw" the empty space around the image) they can be cheaper from a GPU perspective. Also, in general vector sprites are much smaller than their bitmap equivalents - for the fireman example above the sizes of the various sprite types are as follows:Bitmap at 70x68 = 4x70x68 bytes x 12 frames = 223k
Vector = 54k
If you quadruple the resolution of the sprite:Bitmap at 280x272 = 4x280x272 bytes x 12 frames = 3570k
Vector = 54k
So as you can see a lot of memory can potentially be saved by using vector sprites, and we still have a lot of potential for future space savings.
Currently GameMaker Studio 2 can only import vector images from SWF format files, and the way of importing them into the program is almost identical to that for adding a normal bitmap image. To add a vector sprite, create a new sprite, which will bring up the standard Load Sprite dialogue, but make sure that you have selected *.swf from the file filter at the bottom.
Hitting the "load" button will add the vector image or animation to the resource tree, with a progress bar being shown as the file is processed. Note that, depending on the complexity of the file, this can take a while (up to a minute for more complex animations). When processing has finished you'll be returned to the sprite properties dialogue, which will now look like this:
As you can see it looks like the normal sprite dialogue, with the first frame of the vector file shown in the image preview window on the right. There are a couple of changes from a normal sprite dialogue though. Firstly, the Edit Sprite button has gone since there aren't any bitmaps to edit in this sort of sprite, and secondly, a new Show Sprite button has been added. This button will open the vector file in whatever application is associated with it. This would normally default to your web browser, but if you do not have a program associated with the file, then nothing will happen and as the button is disabled (you can resolve this by opening Windows Explorer and right-clicking on a vector file, then using "open with" to choose the program to associate with these files). You can also associate a viewer for these sprites in the General Preferences - Paths section within GameMaker Studio 2 and the Show Sprite button will open that instead of the default viewer.
NOTE: How the image looks in your chosen preview editor will not be the same as how it looks in your game, nor how it looks in the preview window of the sprite editor. The vector image will be imported at the size it was created at, which is not necessarily the size that the preview is shown at (browsers will normally scale the image to fit, for example).
You can also set the quality of the vector sprite when drawn. This will simply reduce or increase the number of triangles used to generate the sprite, with the default quality value of 50 being sufficient normally for most games, however you should experiment with this value if you are using extreme scaling, or are having performance issues. From this point the other parts of the editor should function the same as they do for bitmap sprites.
There are a number of things that you should be aware of when importing vector sprites, with the most important being that some of the sprite drawing and sprite management functions are not supported for technical reasons, particularly those draw functions that draw only part of a sprite, or that "skew" the position in some way (see the individual draw_sprite_*() functions for exact details of which). However the basic sprite drawing functions are fully supported as are the built in sprite variables. You can also set different anti-aliasing (AA) values for the SWF sprites being drawn using the functions found here: Drawing Sprites And Tiles.
You should also be aware of the following:
- When importing a *.SWF file, Actionscript is not supported, so if your SWF relies on it to work correctly then it probably won't turn out right. Similarly, any embedded movie clips that have their own timeline will only have their first frame shown throughout the animation - all animation must be on the main timeline.
- If your vector file has particularly fine detail you may occasionally find that holes or strange triangles will appear in the resulting sprites. This is because at small scales geometry can sometimes collapse together to create shapes that just don't triangulate well. In this case you have two options - you can scale up the contents of the vector file which will give the importer more room to play with, or you can try to reduce the level of detail in the object that is breaking.
- GameMaker Studio 2 uses the stage size of the SWF as the bounds of the resulting sprite. However, if you have anything on the stage outside these bounds it is still drawn. This means that you should either try to avoid putting anything outside your stage bounds if you don't want it to be shown, or use a mask layer to limit drawing to this area.
- The stage size also affects the size of any collision masks that are generated, therefore if you have a large stage size and a lot of frames in your animation you can potentially eat up a lot of memory. So, only use precise collision masks if you really need it.
- As a SWF file is created from multiple layers, some of which potentially overlap, alpha doesn't work quite the way it does with bitmap sprites - overlapping areas will not look as transparent as other parts of the sprite, as the pixels there are being drawn over multiple times.
- Bitmap fills are supported though if you use tiled bitmap fills as part of your SWF file you need to make sure the bitmap is a power-of-two in size, otherwise it won't tile properly. Text rendering is also supported, but you need to embed the font in your SWF file for it to show up in the resulting sprite. Also, currently only left-aligned single line text is supported.
A sprite made using skeletal animation, is one in which a base "skeleton" has been created and animated using key-frames to move the component parts of the skeleton over time. This skeleton is then skinned from a texture atlas and the resulting animation exported in one of many file types. Gamemaker:Studio permits you to import this type of sprite as long as it has been exported as a *.json format file and has the correctly associated texture atlas file (*.atlas) and image file (as a *.png) in the same directory.IMPORTANT: GameMaker Studio 2 only supports a single texture atlas per sprite.NOTE: This feature currently only supports files created using the program Spine.
Currently GameMaker Studio 2 can only import vector images from JSON format files made by the program Spine, however the way to import them into the program is almost identical to that for adding a normal bitmap image. To add a skeletal animation, you need to create a new sprite, which will bring up the standard Load Sprite dialogue, but make sure that you have selected *.json from the file filter at the bottom.
Hitting the "load" button will add the skeletal animation to the resource tree as a sprite, with a progress bar being shown as the file is processed. Note that, depending on the complexity of the file, this may take a moment or two. When processing has finished you'll be returned to the sprite properties dialogue, which will now look like this:
Once you have imported the animation, you can set the collision properties, but note that you are limited here to simply using precise collisions or bounding box collisions, and that the collision data for a skeletal animation is explicitly taken from the data provided. GameMaker Studio 2 does not generate any collision mask if the data is missing from imported file, meaning you simply won't get working collisions if the masks are not set correctly in the program used to create the image being imported.NOTE: Due to the complexity of skeletal animations, the preview image shown in the sprite editor is not intended to accurately represent your animation, but rather give you a simple image that represents the animation for visualising in the room editor.
Unlike bitmap sprites, the imported skeletal animation sprite cannot be modified in the editor in any way, but there are a number of functions available within the GameMaker Language (GML) which can be used to change skins, set properties, and control other aspects of the animation.
There are a number of things that you should be aware of when importing skeleton animation sprites, with the most important being that some of the sprite drawing and sprite management functions are not supported for technical reasons, particularly those draw functions that draw only part of a sprite, or that "skew" the position in some way (see the individual draw_sprite_*() functions for exact details of which). However the basic sprite drawing functions are fully supported as are the built in sprite variables. Apart from these functions and variables, you can also set and change animation properties using special skeleton_* functions, which are listed and explained in the reference section on Skeletal Animations.