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After reading this page you should be able to understand what floor tiles are, and how to make and incorporate them into the FreedroidRPG game.
A repeating geometric pattern that covers a surface is one that tessellates. FreedroidRPG uses tessellating rhombi (think of it as a square that has been rotated 45░ and squished in half). Other games use other shapes, for example The Battle for Wesnoth uses tessellating hexagons.
Doing it with Inkscape (recommended)
Inkscape is a free software vector graphics drawing program that uses the xml-based .svg format. The .svg format a built-in way to transform the coordinate system of all the sub-elements. We exploit this coordinate transformation so we can design our tiles using squares and simple math, but export our tiles as rhombi.
Step 1: Make some layers in Inkscape
Before designing your tile, open up the layers dialog (see the two images below). It should have one layer like this. The plus sign adds layers and the minus sign deletes them. Double clicking on the name allows you to change the layer name, and enter commits the change. The highlighted layer is the active layer.
Or press Ctrl+Shift+L.
We will want to create two sub-layers. Click the plus sign. It should look similar to this. Select "As sublayer of current" in the pulldown menu. Do this twice.
When you are done you should have something like this.
Design your tile within the innermost layer here. You can add additional layers inside this one if you want to keep yourself organized, but keep within this innnermost layer.
Step 2: Design your tile
Make your tile so that you fill up a square. At this point the size of the square does not matter (47px, 100px, or 125px are already calculated). Note that north in the game is oriented with the top of the square.
Your tile has eight surrounding tiles - 4 edges and 4 corners. You might like to look at the 12 possible (out of 17) different Wallpaper groups that do not have a rotation of 360░/6 or 360░/3 for inspiration. Snub square tiling, Truncated square tiling, and Cairo pentagonal tiling are some possibilities for patterns.
There are many ways of doing things in Inkscape. Automatic tiling, shading, and bluring are all supported.
Step 3: Resize your tile to 47px by 47px
After you have created your tile open the xml dialog (see the images below). Click the triangle to open up the second layer. Click on the second layer to highlight it. Type "transform" in the small box, and scale(0.47,0.47) (for 100px squares), scale(0.376,0.376) (for 125px squares), etc such that the resulting square is 47px by 47px and click on "set".
Step 4: Isometric Projection and 2D
A similar process occurs to make the square into the correct rhombus. In the xml editor, highlight the outermost layer. Type "transform" in the small box and matrix(1.4142136,0.7071068,-1.4142136,0.7071068,66.5,0) in the large box and click on "set".
Step 5: Export Bitmap
Your tile should now be the right shape and size. Open up the Export Bitmap dialog under "File" (see the images below). The dialog should be like as shown below, with a Width of 133 and a Height of 66. Select a filename for your image and click "Export" to make a .png file.
Step 6: Post processing?
You can still edit the exported .png image a little bit. I found opening up a pattern with GIMP and running the "clothify" filter, with a Elevation of about 70, and a Depth of 1 made some tiles look a lot more like carpet.
Doing it with blender
Blender is a free and open-source 3D computer graphics software product used for creating animated films, visual effects, interactive 3D applications or video games. Blender's features include 3D modeling, UV unwrapping, texturing, rigging and skinning, fluid and smoke simulation, particle simulation, animating, rendering, video editing and compositing.
Step 1: Drawing the texture
Using your favorite drawing tool, prepare a good quality texture to use. Recommended size is 100x100 or more. The texture must tile: this means that if you repeat your texture, by sticking it next to itself, the transition must not be seen. Textures that don't tile will lead to floor tiles that cannot be accepted into FreedroidRPG.
Step 2: Rendering the floor tile
Open up Blender, make a new scene.
Delete the default cube (press X) and create an horizontal plane (Add -> Mesh -> Plane).áSelect your plane (right click on it), and go into the shading panel (F5). Click "add new" to add a material - a bunch of new options appear. You will see R G and B sliders, and below, a A slider. Pull that A slider to 0.
Go into the texture panel (F6), click add new to create a texture, and select "image" in the texture type list. At the right of the panel, click "load" and select the texture you made in the previous step.
Go back to the shading panel, at the very right click "MapTo" tab, and click Alpha (once).
Set up the camera by selecting it and pressing the N key. Set LocX to -2.828, LocY to -2.828, LocZ to 4, all Scale parameters to 1.0, RotX to 60, RotY to 0, RotZ to -45. With the camera still selected, go into the "edit" panel (F9), and click the "Orthographic" button. The camera must use a scale of 7.31. Go into the shading panel (F5), you will see a World list - click on the cross next to it to delete it. In the scene screen (F10), select PNG format, RGBA mode, width 200 height 240. Hit F12 to check that your plane renders well, and if everything is fine hit ANIM to render your floor tile to a file.
Integrating the floor tile into the game
Once you have the PNG file for your new tile (from the Inkscape or Blender steps above), you have to make an offset file for it. The offset specifies the position of the center of the tile in the image. If you followed the Inkscape procedure, simply copy the 0023.offset file to <yourtile>.offset.
Step 1: In the graphics
The first step is to re-create the floor tiles atlas to take your new file into account. You need to do that every time a floor tile changes.
1) Go into freedroid/graphics/floor_tiles
The output should look something like this :
Creating atlas in atlas.txt from 144 images.
Step 2: In the code
In a first time, you need to add the name of your floor tile image at the end of the underlay_floor_tile_filenames array.
Then, you need to declare a new symbolic name for your floor tile.
grep -H -n "FLOOR_EMPTY" src/defs.h
Now, go into the file and add the new symbolic name (ISO_MY_NEW_FLOOR_TILE for example) at the end of the enumeration.
Then, you need to add your new floor tile in the level editor.
grep -H -n "floor_tiles_array\[\]" src/lvledit/lvledit_object_lists.c
Now, go into the file and add the new symbolic name (ISO_MY_NEW_FLOOR_TILE for example) at the end of the array before the -1.
Rebuild the game, start the level editor, go to the FLOOR panel, you have your tile ready for use.