Using Blender

This is a basic crib sheet for creating a mob in Blender. It could be used to create any other mod relatively easily.

On file formats

Minetest uses the 3D rendering library provided by Irrlicht. As of version 1.8.1 Irrlicht can import the following mesh-formats:

Animated objects:

• B3D files (.b3d, r, skeleton)
• Microsoft DirectX (.x, r) (binary & text, skeleton)
• Milkshape (.ms3d, r, skeleton)
• Quake 3 models (.md3, r, morph)
• Quake 2 models (.md2, r, morph)

Static objects:

• Irrlicht scenes (.irr, r/w)
• Irrlicht static meshes (.irrmesh, r/w)
• 3D Studio meshes (.3ds, r)
• Alias Wavefront Maya (.obj, r/w)
• Lightwave Objects (.lwo, r)
• COLLADA 1.4 (.xml, .dae, r/w)
• OGRE meshes (.mesh, r)
• My3DTools 3 (.my3D, r)
• Pulsar LMTools (.lmts, r)
• Quake 3 levels (.bsp, r)
• DeleD (.dmf, r)
• FSRad oct (.oct, r)
• Cartography shop 4 (.csm, r)
• STL 3D files (.stl, r/w)
• PLY 3D files (.ply, r/w)

The minetest engine does not make use of all of these formats though. The server only accepts the following file formats for media:

3d-Models:

• .b3d (B3D)
• .x (Microsoft DirectX)
• .md2 (Quake 2 models)
• .obj (Alias Wavefront Maya /static)

Images (textures):

• .png
• .jpg
• .bmp
• .tga
• .pcx
• .ppm
• .psd
• .wal
• .rgb

Sounds:

• .ogg

and for names, descriptions and other UI stuff the translation file format might also be usefull:

• .tr

Notes: All other media file formats including those Irrlicht might otherwise support are ignored. Different file formats may perform differently in other setups, DirectX and B3D allow animation. Animation in textures is simulated by rotating through linear aligned single frames within a given texture file, a technique called verticalframe animations in contrast to animation by layers as used by the gif format for example. (but this crib sheet doesn't cover all that)

• If you want to be able to export from Blender in B3D (Blitz 3D) format (with 2.70)

1. Download the Blender export script B3DExport.py
2. On GNU/Linux: copy to ~/.config/blender/2.71/scripts/addons
   Alternatively, you can skip this step and see step 4 to see a different method*.
3. Open Blender
4. In Blender open the menu File/User Preferences/Addons. *From here you can press 'Install Add-on from File', navigate to the .py file, and press 'Install'. Now go to File/User Preferences/Addons/Import Export/B3D (Blitz 3D) Model Exporter.
5. Tick the box on the left to enable it
   (If you want .x (directX) then find this and enable it too.)
6. While you're in preferences on the file tab you may want to enable Save&Load/Compress File (for much smaller saved files), and Autosave/Keep Session (to save on exit)
7. Save User Settings
8. Close Preferences Window

• If you want to import, install version 2.49, save as a Blender file, then open with 2.70 to edit.

• Another script is the io_scene_b3d script by joric for Blender 2.80 that may work with Blender 2.79/2.9 (as of Jan.2021) versions.
• Yet another version of io_scene_b3d is maintained by GreenXenith (as of march 2020).
• A python script to export from Blender to DirectX format .x is io_scene_x by hecktest. It is written to work with version 2.8 but this plugin is known to work in Blender versions up to 3.0.0 Alpha as of July 2021. As minetest uses a lefthanded Y-up coordinate space, you may have to adjust some values according to a matrix shown in the readme.md file

Begin with a basic mob

To create a basic mob, copy an animal from animals_modpack-2.3.6. Then in the init.lua you only have to do a search and replace of the name of the animal, and delete any irrelevant code. You can edit speed, acceleration, etc as you wish.

Create a 3D model

Don't bother with materials – Minetest doesn't handle them – you need a texture to define any colours. If you want your model to walk forwards, you must create it with “forward” pointing in the +ve x direction (i.e. right when you select view point KP 7, or facing in the direction of the red “x” arrow when an object is selected).

Create object

1. In 3D View
2. If not already active switch to object mode (dropdown in 3D viewport)
3. Add objects (eg 3D Menu → Add → Mesh → Cube)
4. Move around by right-clicking to select and dragging arrows.
   B box/border select. G grab to move.
   Resize or rotate using the properties viewport (has a row of camera, cube, spanner, etc at top)
5. Select the cube
6. Use rotation and scale to transform objects
   [See the hundreds of Blender tutorials for more advanced editing techniques.]

Save primary Blender model

1. Save as a Blender file (Ctrl-S or File → Save)
2. Save with the name: yourname.blend (or similar)
3. You might also want to save a separate “unjoined” copy before the following join operation, as you won't be able to access the base components afterward

Texturing

When the basic model is completed, you'll need to create a texture.

1. Switch to Object mode
   1. Press A (perhaps twice) to select all objects
   2. Ctrl + J to join all objects in a model together
2. Switch to Edit Mode
   1. Mesh/UV Unwrap/Smart UV Project [see one of the many UV Mapping tutorials if you want seams to match, etc]
      [optional] Set island margin to 0.004 (this leaves a gap between faces, so there will be less risk of bleeding of colour across sharp edges. 0.002 is approx 1 pixel for a 512 pixel image)
3. Move mouse to the top of the 3D window to get and up/down arrow. Right click/split window and size to 50:50.
   1. On the R hand new window select the litle cube (3D viewport) icon and switch to UV Map viewport
   2. LowMenubar:New
      1. Set name - eg 'yourname UV Map'
      2. Click UV Test Grid (optional)
      3. OK (=Save)
         [if you want to resize the image use a power of 2 (512/1024/etc) for x and y dimensions as it significantly speeds processing]
   3. LowMenubar:Image → Pack as PNG → Accept warning (this ensures you will save a copy of the image within the .blend file (I think in 2.4 this may have to be updated manually, but the tickbox in 2.7 implies is should be saved with the rest of the file)
   4. Check UV map fits on image - adjust with: G - move, R - rotate, S - scale (menu:UV → Transform)
      The UV vertices won't always align to pixel boundaries, which means if you don't use 'island margin' above, then painting on one face may also unavoidable paint onto another face. There is reference in the manual to a UV snap-to-pixel option (to align UV vertices to pixel edges) but I haven't figured how to access it yet (and it would only perfectly stop bleed for horizontal or vertically aligned vertices).
4. In 3D View window
   1. Switch to Texture Paint (from Edit Mode)
   2. in the Toolbar set:-
      1. Brush
         Select white (should be selected by default)
         Strength 1.0 (ie 100% replacement of the underlying colour)
         Radi 500 (or whatever brush radius you want)
      2. Curve
         select the square profile if you want a solid colour brush
         select the 'normal distribution curve' if you want a fading brush
         (or any other profile you like)
5. UV Map window
   1. Switch to Paint (from View)
   2. Paint the entire object white (or some other basecoat). This is easiest to do in UV Map window
6. In 3D View window
   1. To paint only particular faces, click the face Menu/faceselect (the cube with grid pattern on the face), you will then be able to select an entire face/s with R click (or shift R-click for multiple faces).
   2. Change colour, strength, radius, curve… and paint the different parts as you wish – painting in either 3D or UV Mesh windows.
      NB the colour picker has an eyedropper to copy the colour from within the 3D or UV Map windows – just click on the currently displayed colour (under the colour wheel) to bring it up.

Animation

1. Make sure your mesh is child of Armature.
2. Make sure there's only one bone parenting all others (having a child bone being parent of another one is no problem).
3. All faces need to be members of a vertex group.
4. Make sure all of your vertex groups have same name as at least one bone.
5. Don't forget to export animation when exporting to .x file.

Save your work and export the files

1. Save the mesh
   1. Export as a .b3d file (File/Export/B3D)
   2. Save with the name: models/animal_yourname.b3d
   3. Don't forget to look for and OK the overwrite message if needed or it will disappear and you won't have saved your file.
2. Save the texture
   1. UV Window → Image → Save As Image
   2. Save with the name: textures/animal_yourname_yourname_mesh.png

Create or copy the inventory texture

Find or create a nice graphic to be the image in the inventory.
A flat texture can be created with a 6 sided cube model (eg animal_yourname_yourname.png)
The inventory image is animal_yourname_yourname_item.png
(Remember to respect copyright – use screenshots of your model, perhaps with the help of a “green screen” for transparency, if you want a simple free graphic. To turn off the 3D viewport grid floor open the propertles menu (+ at top R of window), and untick display/grid floor).

Rendering the model

If you want to be able to render the model (F12'), you'll first need to do the following steps to enable the texture:

1. In 3D edit view. Add → Lamp → Hemi. You might need to move this around to adjust lighting direction, but probably not.
2. In properties viewpane:-
3. Select checkered box tab,
   1. Change texture type to Image → Movie,
   2. Click on image dropdown below this and select your UV texture image,
   3. Under mapping dropdown change coord to UV.

Now, rendering should work…