Blender - Python API #6

Transcription

1 Blender - Python API #6 Serdar ARITAN Department of Computer Graphics Hacettepe University, Ankara, Turkey 1

2 Blender is a free 3D graphics package 3D object modelling Materials and lighting Animation and simulation Video editing and compositing Integrated physics engine Free download, installed in labs Blender can be scripted with Python o Uses Python 3 o Just about everything can be scripted o Creating objects, lights, cameras o Creating and applying materials o Rendering and animation o The Blender interface itself 2

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5 The Blender/Python API can do the following: Edit any data the user interface can (Scenes, Meshes, Particles etc.) Modify user preferences, keymaps and themes Run tools with own settings Create user interface elements such as menus, headers and panels Create new tools Create interactive tools Create new rendering engines that integrate with Blender Define new settings in existing Blender data Draw in the 3D view using OpenGL commands from Python 5

6 The Blender/Python API can t (yet)... Create new space types. Assign custom properties to every type. Define callbacks or listeners to be notified when data is changed. 6

7 Note: The Blender Python API has areas which are still in development. The following areas are subject to change. operator behavior, names and arguments mesh creation and editing functions These parts of the API are relatively stable and are unlikely to change significantly data API, access to attributes of blender data such as mesh verts, material color, timeline frames and scene objects user interface functions for defining buttons, creation of menus, headers, panels render engine integration modules: bgl, mathutils & game engine 7

8 Three main components in Python API bpy.data contains objects, scenes, materials, etc. bpy.context information about current state - e.g.: selected objects bpy.ops operations on the scene such as adding an object, rotation, etc. 8

9 Blender uses Python 3.x; some 3rd party extensions are not available yet. The interactive console is great for testing one-liners, It also has auto complication so you can inspect the api quickly. Button tool tips show Python attributes and operator names. Right clicking on buttons and menu items directly links to API documentation. For more examples, the text menu has a templates section where some example operators can be found. To examine further scripts distributed with Blender, see ~/.blender/scripts/startup/bl_ui for the user interface and ~/.blender/scripts/startup/bl_op for operators. 9

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18 To check what symbols are loaded into the default environment, type dir() and press <ENTER> 18

19 bpy. and then press <CTRL>+<SPACE> and you will see the Console auto-complete. 19

20 >> bpy.app.binary_path 'C:\\Blender\\blender-2.79-windows64\\blender-app.exe' >>> bpy.app.version <CTRL><SPACE> _char _cycle _string >>> bpy.app.version (2, 79, 0) >>> bpy.app.version_string '2.79 (sub 0)' 20

21 Contextual access of information in a Blender file/scene >> bpy.context.mode 'OBJECT' # Will print the current 3D View mode # (Object, Edit, Sculpt etc.,) >>> bpy.context.object bpy.data.objects['cube'] >>> C.mode 'OBJECT' >>> C.object bpy.data.objects['cube'] 21

22 Contextual access of information in a Blender file/scene >> bpy.context.mode 'OBJECT' >>> bpy.context.object bpy.data.objects['cube'] >>> bpy.context.object bpy.data.objects['camera'] 22

23 Contextual access of information in a Blender file/scene >>> bpy.context.selected_objects [bpy.data.objects['cube'], bpy.data.objects['lamp'], bpy.data.objects['camera']] 23

24 Data access of information in a Blender file/scene >> for object in bpy.data.scenes['scene'].objects:... print(object.name)... Camera Cube Lamp You can access following data in the current Blender file objects, meshes, materials, textures, scenes, screens, sounds, scripts, texts, cameras, curves, lamps, brushes, armatures, images, lattices, libraries, worlds, groups, metaballs, particles, node_groups 24

25 Data access of information in a Blender file/scene >> for object in bpy.data.objects:... print(object.name + is at location' + str(object.location))... Camera is at location<vector (7.4811, , )> Cube is at location<vector (0.0000, , )> Lamp is at location<vector (4.0762, , )> 25

26 Python access to calling operators in Blender file/scene >>> add_cube = bpy.ops.mesh.primitive_cube_add >>> for index in range(5):... add_cube(location=(index*3, 0, 0))... {'FINISHED'} {'FINISHED'} {'FINISHED'} {'FINISHED'} {'FINISHED'} 26

27 Import Libraries Importing the Blender Python API is the first step for any Blender script. import bpy import mathutils import math # Imports the Blender Python API # Imports Blender vector math utilities # Imports the standard Python math library # Set up some variables a = 'hello' b = ' world! # Print the addition to the system console print (a + b) # open the system console! bpy.ops.wm.console_toggle() 27

28 Blender's 'Info' view port shows you all recent Blender activity as executable Python commands. This is very handy for prototyping a process using modeling methods and then assembling them into a script The selected text from above can be copied and pasted into the Text Editor. We can delete any unneeded options from the command. This script will create a single mesh cube in the scene. import bpy #Imports the Blender Python API # Create a mesh cube in the scene bpy.ops.mesh.primitive_cube_add(location=(5, 5, 5)) 28

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30 for i in range (0, 5): x = i * 3 y = 0 z = 0 # Create a mesh cube in the scene bpy.ops.mesh.primitive_cube_add(location=(x, y, z)) 30

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34 Select the objects to rename 34

35 Run the script 35

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39 Data Access (bpy.data) import bpy # print all objects for obj in bpy.data.objects: print(obj.name) # print all scene names in a list print(bpy.data.scenes.keys()) # remove Cube if bpy.data.objects.find('cube') >= 0: cubeobj = bpy.data.objects['cube'] bpy.data.scenes[0].objects.unlink(cubeobj) bpy.data.objects.remove(cubeobj) 39

40 Data Access (bpy.data) # write images into a file next to the blend import os import bpy file = open(os.path.splitext(bpy.data.filepath)[0] + ".txt", 'w') for image in bpy.data.images: file.write("%s %d x %d\n" % (image.filepath, image.size[0], image.size[1])) file.close() 40

41 Operators (bpy.ops) 41

42 import bpy if bpy.data.objects.find('cube') >= 0: cubeobj = bpy.data.objects['cube'] bpy.data.scenes[0].objects.unlink(cubeobj) bpy.data.objects.remove(cubeobj) cameraobj = bpy.data.objects['camera'] # Create and name TextCurve object bpy.ops.object.text_add(location=(0, 0, 0)) #bpy.ops.object.editmode_toggle() #bpy.ops.font.delete() #bpy.ops.font.text_insert(text="") 42

43 txtobject = bpy.context.object txtobject.name = 'myname' textcurve = txtobject.data textcurve.name = 'thedata' # TextCurve attributes textcurve.body = 'Serdar' textcurve.font = bpy.data.fonts[0] textcurve.offset_x = 0 textcurve.offset_y = 0 textcurve.shear = 0 textcurve.space_character = 1 textcurve.size = 3 textcurve.space_word = 0 # Inherited Curve attributes textcurve.extrude = 0.1 bpy.data.objects['myname'].location.x -= 3 43

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45 import bpy scene = bpy.context.scene fp = scene.render.filepath # get existing output path scene.render.image_settings.file_format = 'PNG' # set output format to.png for frame_nr in range(1, 11): bpy.ops.transform.rotate(value= 0.1, axis=(0, 1, 0)) scene.frame_set(frame_nr) # set output path so render won't get overwritten scene.render.filepath = fp + str(frame_nr) bpy.ops.render.render(write_still=true) # render still # restore the filepath scene.render.filepath = fp 45

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47 import bpy outputfile = "deneme1.txt" writefile = open(outputfile, 'w') # verts writefile.write("verts=[\n") print("verts=[\n") for i in bpy.context.active_object.data.vertices: print(i.co, ",") coords = i.co.x, i.co.y, i.co.z writefile.write(str(coords) + ",\n") print("]") writefile.write("]\n\n\n\n") 47

48 # faces writefile.write("faces=[\n") print("faces=[\n") for i in bpy.context.active_object.data.polygons: verts_on_face = i.vertices[:] print(verts_on_face) writefile.write(str(verts_on_face)+",\n") print("]") writefile.write("]\n\n\n\n") # close the file. writefile.close() 48

49 Addon Tutorial 49

50 Addon Tutorial 50

51 Addon Tutorial 51

52 Once you have your addon within in Blender s text editor, you will want to be able to install it so it can be enabled in the user preferences to load on startup. Even though the addon above is a test, lets go through the steps anyway so you know how to do it for later. To install the Blender text as an addon you will first have to save it to disk, take care to obey the naming restrictions that apply to Python modules and end with a.py extension. Once the file is on disk, you can install it as you would for an addon downloaded online. Addon Tutorial Open the user File -> User Preferences, Select the Addon section, press Install Addon... and select the file. Now the addon will be listed and you can enable it by pressing the check-box, if you want it to be enabled on restart, press Save as Default. 52

53 Command-line / subprocess You can use subprocess to run blender from python. Use the -b / --background switch to run blender in the background (GUI-less). Use the -P <filename> / --python <filename> switch to load desired python script. Or use --python-console to run python from stdin. Example: blender --background --python myscript.py 53

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