Step 4 - Defining Tile Categories and Solidity
Tiles are categorized for two purposes. Mainly, these categories can be used to create a solidity definition. A solidity definition determines which tiles are solid and what shape they are so that sprites can react to solid areas of the map properly. Secondly, categories are used in defining inventory/map interactions for the player. For instance, if the player could eliminate any "boulder" tiles from the map when in posession of a "pickaxe" item, all images of boulders would be categorized together as tiles affected by the pickaxe. This step of the tutorial will lead you through creating both types of categories.
To access the Tile Categories dialog, select "Tile Categories" from the View Menu in the main project window.
This dialog allows you to categorize the tiles of a tileset into named categories. Each tileset has its own distinct index of category names. That is to say, you can define a category called "Solid" for the "Tutorial" tileset, and define another category called "Solid" for another tileset.
Of course this tutorial only deals with a single tileset so all the categories will apply to that tileset. Start by selecting the tileset in the "Tileset" box. Type the name "Solid" in the "Current Category" box. The category will automatically be created once you drag a tile from the "Tiles available" box to the "Tiles in this category" box.
In the "Tiles available" box, locate all the tiles that were included in the Tilematch definition from step 2. Of these tiles, drag all the tiles without any black pixels into the "Tiles in this category" box. This category will define tiles that are solid squares.
To create another category, type the name of the category in "Current Category". As you start dragging you will see the "Tiles in this category" box go blank indicating a new category. The list below indicates more categories you should create, and which tiles belong in them.
These are all the categories required to make one complete "Solidity Definition". Enter the name "TutorialSolid" into the "Solidity Definition Name" box. Then select "Solid" in the "Solid tile category" box, select "Uphill" in the "Uphill tile category" box and so on until each box has a tile category specified. Save the solidity definition by clicking the "Save" button.
This completes the solidity definition, now let's add a few categories to use with the player's inventory and map interaction.
First we'll categorize the two items in their own categories. Sometimes it may be useful to categorize multiple tiles as a single item (if multiple pictures can represent the same inventory item) but this is not the case here.
Type the name "Staff" in the "Current Category" field and drag the tile representing the staff into the "Tiles in this category" box. Then type the name "Scraper" in the "Current Category" field and drag the scraper tile into the category. There should now be a total of 7 categories.
To make things interesting, the scraper item should probably not break through all walls, just exterior walls. To make this easy, we'll add all the exterior wall tiles to a category. Type the name "Exterior" into the "Current Category" field. Drag all tiles, that are part of the Tilematch definition (defined in step 2) and that also contain white (edge) pixels into the category.
Those are all the categories we'll be using in this tutorial. Some other points to note about categories:
Now is a good time to save the project again. All the tile categories and solidity definitions are stored in the .GDP project file.
This concludes Step 4 of the GameDev tutorial - Defining Tile Categories and Solidity.
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