blender as research tool · sybren a. stüvel - [email protected] blender as research tool: from...

Blender as research toolBlender as research toolfrom data to visualizationfrom data to visualization

Sybren A. Stüvel - [email protected] A. Stüvel - [email protected] Blender as research tool: Blender as research tool: from data to visualizationfrom data to visualization Blender conference 2013Blender conference 2013

Sybren A. StüvelSybren A. Stüvel

● Blender user for 10 yearsBlender user for 10 years● Python user for 8 yearsPython user for 8 years● Programming & drumming since 1991Programming & drumming since 1991● Doing a PhD in crowd animation (Universiteit Utrecht)Doing a PhD in crowd animation (Universiteit Utrecht)

● http://stuvel.eu/http://stuvel.eu/http://stuvelfoto.nl/http://stuvelfoto.nl/http://soundabout.nl/http://soundabout.nl/


Overview of the workshopOverview of the workshop

● My researchMy research● Creating 3D objects with PythonCreating 3D objects with Python● Easier reuse: creating an OperatorEasier reuse: creating an Operator● Extending the user interfaceExtending the user interface● Loading from a databaseLoading from a database● Putting it all togetherPutting it all together● DiscussionDiscussion


My researchMy research

● Utrecht UniversityUtrecht University● Virtual Human Technology LabVirtual Human Technology Lab

● Crowd animationCrowd animation● Densely packedDensely packed


Bounding Circle HierarchyBounding Circle Hierarchy

● Occupancy spacesOccupancy spaces● Represented using Represented using

Bounding Circle HierarchiesBounding Circle Hierarchies● Find bounding circleFind bounding circle● Recursively subdivideRecursively subdivide



● Occupancy spacesOccupancy spaces● Represented using Represented using

Bounding Circle HierarchiesBounding Circle Hierarchies● Find bounding circleFind bounding circle● Recursively subdivideRecursively subdivide

● Stop when they are small Stop when they are small enoughenough


Intersection testsIntersection tests

● Intersections between BCHsIntersections between BCHs● Bottom circles don't Bottom circles don't

intersect no intersection→intersect no intersection→● Otherwise: check sub-circlesOtherwise: check sub-circles● Tricky, and of course I made Tricky, and of course I made

a mistake...a mistake...


Benchmarking the audienceBenchmarking the audience

● Who has experience with...Who has experience with...● … … programming?programming?● … … programming in Python?programming in Python?● … … Blender scripting with Python?Blender scripting with Python?● … … Linear algebra / coordinate transformations?Linear algebra / coordinate transformations?


Please interruptPlease interrupt


CodingCoding

1)Create a circle mesh from PythonCreate a circle mesh from Python

2)Duplicate it a lotDuplicate it a lot

3)Create an OperatorCreate an Operator

4)Connect it to the GUIConnect it to the GUI

5)Connect to the databaseConnect to the database


Creating objectsCreating objects

We need to:We need to:

● Add a circleAdd a circle● Scale itScale it● Position itPosition it

… … and do it again, and again, and again....and do it again, and again, and again....

As one hierarchy contains roughly 1400 circles!As one hierarchy contains roughly 1400 circles!



● Ensure there is one circle meshEnsure there is one circle mesh– ±± 1500 circles per hierarchy 1500 circles per hierarchy

– 32 vertices per circle32 vertices per circle

– 2 hierarchies2 hierarchies

– 96000 vertices96000 vertices

● For each circle, create object that shares this meshFor each circle, create object that shares this mesh

● Scale & position the objectScale & position the object


If you don't see the Python tooltip...If you don't see the Python tooltip...


Creating objectsCreating objectsimport bpyimport bpyfrom math import pifrom math import pi

def layer(n):def layer(n): return (n-1) * [False] + [True] + (20-n) * [False]return (n-1) * [False] + [True] + (20-n) * [False]

bpy.ops.mesh.primitive_circle_add(bpy.ops.mesh.primitive_circle_add( radius=1.0,radius=1.0, vertices=32,vertices=32, fill_type='NGON',fill_type='NGON', location=(0, 0, 0),location=(0, 0, 0), rotation=(pi/2, 0, 0))rotation=(pi/2, 0, 0))bpy.ops.object.transform_apply(rotation=True)bpy.ops.object.transform_apply(rotation=True)

base_circle = bpy.context.scene.objects.activebase_circle = bpy.context.scene.objects.activebase_circle.name = 'base_circle'base_circle.name = 'base_circle'base_circle.data.name = 'base_circle'base_circle.data.name = 'base_circle'

# Add material# Add materialbpy.ops.object.material_slot_add()bpy.ops.object.material_slot_add()mat = bpy.data.materials['circle']mat = bpy.data.materials['circle']base_circle.material_slots[0].material = matbase_circle.material_slots[0].material = mat

base_circle.layers = layer(10)base_circle.layers = layer(10)


Cloning objectsCloning objects

1) Create the cloneCreate the clone

2) Link it to the current sceneLink it to the current scene

3) Set propertiesSet properties


Cloning objectsCloning objects

clone = base_circle.copy()clone = base_circle.copy()bpy.context.scene.objects.link(clone)bpy.context.scene.objects.link(clone)

clone.layers = layer(4)clone.layers = layer(4)clone.name = 'Circle 4'clone.name = 'Circle 4'


OperatorOperator

● Subclasses bpy.types.OperatorSubclasses bpy.types.Operator

● Has an identifierHas an identifier

● Can be executedCan be executed

● Can be bound to button in GUICan be bound to button in GUI


OperatorOperator


OperatorOperatorclass LoadCircleHierarchy(bpy.types.Operator):class LoadCircleHierarchy(bpy.types.Operator): bl_idname = 'import_mesh.circle_hierarchy'bl_idname = 'import_mesh.circle_hierarchy' bl_label = 'Import Bounding Circle Hierarchy'bl_label = 'Import Bounding Circle Hierarchy'

top_circle_id = bpy.props.IntProperty(top_circle_id = bpy.props.IntProperty( description='Database ID of the top-level circle')description='Database ID of the top-level circle')

circle_layer_nr = bpy.props.IntProperty(default=4)circle_layer_nr = bpy.props.IntProperty(default=4)


Operator executionOperator execution

class LoadCircleHierarchy(bpy.types.Operator):class LoadCircleHierarchy(bpy.types.Operator): bl_idname = 'import_mesh.circle_hierarchy'bl_idname = 'import_mesh.circle_hierarchy' bl_label = 'Import Bounding Circle Hierarchy'bl_label = 'Import Bounding Circle Hierarchy'

top_circle_id = bpy.props.IntProperty(top_circle_id = bpy.props.IntProperty( description='Database ID of the top-level circle') description='Database ID of the top-level circle') circle_layer_nr = bpy.props.IntProperty(default=4)circle_layer_nr = bpy.props.IntProperty(default=4) def execute(self, context):def execute(self, context): if not self.top_circle_id:if not self.top_circle_id: return {'CANCELLED'}return {'CANCELLED'} return {'FINISHED'}return {'FINISHED'}


RegistrationRegistration

● Operators need to be registeredOperators need to be registered

● As simple as:As simple as:

bpy.utils.register_module(__name__)bpy.utils.register_module(__name__)

at the bottom of your source file, and checking “Register”at the bottom of your source file, and checking “Register”


FeedbackFeedback

def execute(self, context):def execute(self, context): if not self.top_circle_id:if not self.top_circle_id: self.report({'ERROR'}, 'Loading BCH impossible, no database ID')self.report({'ERROR'}, 'Loading BCH impossible, no database ID') return {'CANCELLED'}return {'CANCELLED'} self.report({'INFO'}, 'Loading BCH finished')self.report({'INFO'}, 'Loading BCH finished') return {'FINISHED'}return {'FINISHED'}


Extending the UIExtending the UI

● Like operator:Like operator:– extend certain class: extend certain class: bpy.types.Panelbpy.types.Panel

– set propertiesset properties

– implement methodimplement method

– register moduleregister module


Places in the UIPlaces in the UI

● All sorts of different spots for the UI elementsAll sorts of different spots for the UI elements● bl_space_type = "VIEW_3D"bl_space_type = "VIEW_3D"

– bl_region_type = "TOOLS"bl_region_type = "TOOLS"

– bl_region_type = "TOOL_PROPS"bl_region_type = "TOOL_PROPS"

– bl_region_type = "UI"bl_region_type = "UI"

● bl_space_type = "PROPERTIES"; bl_region_type = "WINDOW"bl_space_type = "PROPERTIES"; bl_region_type = "WINDOW"– bl_context = "object"bl_context = "object"

– bl_context = "material"bl_context = "material"

– bl_context = "world"bl_context = "world"


Extending the UIExtending the UIimport bpyimport bpy

class BoundingCircles(bpy.types.Panel):class BoundingCircles(bpy.types.Panel): bl_label = "Bounding Circles Hierarchy"bl_label = "Bounding Circles Hierarchy" bl_space_type = "PROPERTIES"bl_space_type = "PROPERTIES" bl_region_type = "WINDOW"bl_region_type = "WINDOW" bl_context = "world"bl_context = "world" def draw(self, context):def draw(self, context): … … draw stuff here …draw stuff here …



Loading from a databaseLoading from a database● SQLite databaseSQLite database

– Python has built-in supportPython has built-in support

● ““circles”circles”– idid integer integer

– centre_xcentre_x, , centre_zcentre_z, , squared_radiussquared_radius real real

– sub_asub_a, , sub_bsub_b integer references circles(id) integer references circles(id)

● ““hierarchies”hierarchies”– identifieridentifier varchar(255) varchar(255)

– top_circle_idtop_circle_id integer references circles(id) integer references circles(id)


Coordinate transformationCoordinate transformation

● Our tooling is based on OgreOur tooling is based on Ogre– XZ = ground plane, Y = up XZ = ground plane, Y = up

● Load data into BlenderLoad data into Blender– XY = ground plane, Z = upXY = ground plane, Z = up


List hierarchies in GUIList hierarchies in GUI

● Iterate over the hierarchiesIterate over the hierarchies

● Add the identifier as a labelAdd the identifier as a label

● Add a button to load that hierarchyAdd a button to load that hierarchy


List hierarchies in GUIList hierarchies in GUI

import bpyimport bpyimport sqlite3import sqlite3

dbfile = bpy.path.abspath('//bounding_hierarchy.sqlite')dbfile = bpy.path.abspath('//bounding_hierarchy.sqlite')print('%s: Database file: %r' % (__name__, dbfile))print('%s: Database file: %r' % (__name__, dbfile))

class BoundingCircles(bpy.types.Panel):class BoundingCircles(bpy.types.Panel): bl_label = "Bounding Circles Hierarchy"bl_label = "Bounding Circles Hierarchy" bl_context = "world"bl_context = "world" bl_space_type = "PROPERTIES"bl_space_type = "PROPERTIES" bl_region_type = "WINDOW"bl_region_type = "WINDOW"

def draw(self, context):def draw(self, context): '''Draws the layout.''''''Draws the layout.''' db = sqlite3.connect(dbfile)db = sqlite3.connect(dbfile) try:try: self.draw_using(db)self.draw_using(db) finally:finally: db.close()db.close() def draw_using(self, db):def draw_using(self, db): '''Draws the layout using a certain database connection.''''''Draws the layout using a certain database connection.'''

layout = self.layoutlayout = self.layout

layout.label("Hierarchies in database")layout.label("Hierarchies in database") row = layout.row()row = layout.row() box = row.box()box = row.box() c = db.cursor()c = db.cursor() c.execute('select identifier, top_circle_id from hierarchies order by identifier')c.execute('select identifier, top_circle_id from hierarchies order by identifier') for dbrow in c:for dbrow in c: (identifier, top_circle_id) = dbrow(identifier, top_circle_id) = dbrow

split = box.split(percentage=0.8)split = box.split(percentage=0.8) row = split.row()row = split.row() row.label(text=identifier, translate=False)row.label(text=identifier, translate=False) # BCH Load buttons# BCH Load buttons row = split.row(align=True)row = split.row(align=True) if top_circle_id:if top_circle_id: props = row.operator("import_mesh.circle_hierarchy", text="BCH")props = row.operator("import_mesh.circle_hierarchy", text="BCH") props.top_circle_id = top_circle_idprops.top_circle_id = top_circle_id


Loading the BCHLoading the BCH

● We know database ID of top circleWe know database ID of top circle

● Clone the base circleClone the base circle

● Do coordinate-transformation and position/scaleDo coordinate-transformation and position/scale

● Recurse over sub-circles (if any)Recurse over sub-circles (if any)


import bpyimport bpyfrom mathutils import Vector, Matrixfrom mathutils import Vector, Matrixfrom math import pifrom math import piimport sqlite3import sqlite3

dbfile = bpy.path.abspath('//bounding_hierarchy.sqlite')dbfile = bpy.path.abspath('//bounding_hierarchy.sqlite')print('%s: Database file: %r' % (__name__, dbfile))print('%s: Database file: %r' % (__name__, dbfile))ogre2blender = Matrix.Rotation(pi / 2, 4, "X")ogre2blender = Matrix.Rotation(pi / 2, 4, "X")

def layer(n):def layer(n): return (n-1) * [False] + [True] + (20-n) * [False]return (n-1) * [False] + [True] + (20-n) * [False]

if 'base_circle' in bpy.data.objects:if 'base_circle' in bpy.data.objects: base_circle = bpy.data.objects['base_circle']base_circle = bpy.data.objects['base_circle'] bpy.context.scene.objects.active = base_circlebpy.context.scene.objects.active = base_circleelse:else: bpy.ops.mesh.primitive_circle_add(bpy.ops.mesh.primitive_circle_add( radius=1.0,radius=1.0, vertices=32,vertices=32, fill_type='NGON',fill_type='NGON', location=(0, 0, 0),location=(0, 0, 0), rotation=(pi/2, 0, 0))rotation=(pi/2, 0, 0)) bpy.ops.object.transform_apply(rotation=True)bpy.ops.object.transform_apply(rotation=True) # Set up the circle object & data names.# Set up the circle object & data names. base_circle = bpy.context.scene.objects.activebase_circle = bpy.context.scene.objects.active base_circle.name = 'base_circle'base_circle.name = 'base_circle' base_circle.data.name = 'base_circle'base_circle.data.name = 'base_circle' # Add material# Add material bpy.ops.object.material_slot_add()bpy.ops.object.material_slot_add() mat = bpy.data.materials['circle']mat = bpy.data.materials['circle'] base_circle.material_slots[0].material = matbase_circle.material_slots[0].material = mat base_circle.layers = layer(10)base_circle.layers = layer(10)

class LoadCircleHierarchy(bpy.types.Operator):class LoadCircleHierarchy(bpy.types.Operator): bl_idname = 'import_mesh.circle_hierarchy'bl_idname = 'import_mesh.circle_hierarchy' bl_label = 'Import Bounding Circle Hierarchy'bl_label = 'Import Bounding Circle Hierarchy' top_circle_id = bpy.props.IntProperty(top_circle_id = bpy.props.IntProperty( description='Database ID of the top-level circle')description='Database ID of the top-level circle') matrix = bpy.props.FloatVectorProperty(matrix = bpy.props.FloatVectorProperty( size=16,size=16, default=(default=( 1, 0, 0, 0,1, 0, 0, 0, 0, 1, 0, 0,0, 1, 0, 0, 0, 0, 1, 0,0, 0, 1, 0, 0, 0, 0, 1),0, 0, 0, 1), subtype='MATRIX',subtype='MATRIX', )) circle_layer_nr = bpy.props.IntProperty(default=4)circle_layer_nr = bpy.props.IntProperty(default=4) def execute(self, context):def execute(self, context): if not self.top_circle_id:if not self.top_circle_id: self.report({'ERROR'}, 'Loading BCH impossible, no database ID')self.report({'ERROR'}, 'Loading BCH impossible, no database ID') return {'CANCELLED'}return {'CANCELLED'} print(60 * '=')print(60 * '=') self.transf = ogre2blender * self.matrixself.transf = ogre2blender * self.matrix print('Using transformation matrix:\n%s' % self.transf)print('Using transformation matrix:\n%s' % self.transf) # Load the circles from the DB# Load the circles from the DB db = sqlite3.connect(dbfile)db = sqlite3.connect(dbfile) try:try: self.load_circle(db, self.top_circle_id)self.load_circle(db, self.top_circle_id) finally:finally: db.close()db.close() self.report({'INFO'}, 'Loading BCH %i finished' % self.top_circle_id)self.report({'INFO'}, 'Loading BCH %i finished' % self.top_circle_id) return {'FINISHED'}return {'FINISHED'}

def load_circle(self, db, circle_id, parent_circle_obj=None, depth=0):def load_circle(self, db, circle_id, parent_circle_obj=None, depth=0): # Load the circle from the DB# Load the circle from the DB c = db.cursor()c = db.cursor() c.execute('select * from circles where id=?', (circle_id, ))c.execute('select * from circles where id=?', (circle_id, )) row = c.fetchone()row = c.fetchone() # Create the circle# Create the circle radius = row[3] ** 0.5radius = row[3] ** 0.5

circle = base_circle.copy()circle = base_circle.copy() bpy.context.scene.objects.link(circle)bpy.context.scene.objects.link(circle) circle.layers = layer(self.circle_layer_nr)circle.layers = layer(self.circle_layer_nr) circle.select = Falsecircle.select = False circle.name = 'circle-%i=dbid' % circle_idcircle.name = 'circle-%i=dbid' % circle_id # Loaded in Ogre coordinates, self.transf contains ogre2blender.# Loaded in Ogre coordinates, self.transf contains ogre2blender. location = Vector((row[1], 0.03 * depth, row[2]))location = Vector((row[1], 0.03 * depth, row[2])) mat = self.transf * Matrix.Translation(location) * Matrix.Scale(radius, 4)mat = self.transf * Matrix.Translation(location) * Matrix.Scale(radius, 4) circle.matrix_local = matcircle.matrix_local = mat # Load sub-circles# Load sub-circles if row[4]:if row[4]: self.load_circle(db, row[4], circle, depth + 1)self.load_circle(db, row[4], circle, depth + 1) if row[5]:if row[5]: self.load_circle(db, row[5], circle, depth + 1)self.load_circle(db, row[5], circle, depth + 1)

return circlereturn circle



Loading the polygonLoading the polygon

● The Bounding Circle Hierarchy was based on a polygonal The Bounding Circle Hierarchy was based on a polygonal shapeshape

● This shape is also saved by our software, as OBJThis shape is also saved by our software, as OBJ

● Small modification required to place at correct layerSmall modification required to place at correct layer

● Visually nice: make polygon active objectVisually nice: make polygon active object


OBJ-loading & selecting operatorOBJ-loading & selecting operator

class LoadObjMesh(bpy.types.Operator):class LoadObjMesh(bpy.types.Operator): '''Imports an OBJ file and makes it the active object.''''''Imports an OBJ file and makes it the active object.''' bl_idname = 'import_mesh.obj'bl_idname = 'import_mesh.obj' bl_label = 'Imports OBJ file without prompting user'bl_label = 'Imports OBJ file without prompting user' filepath = bpy.props.StringProperty()filepath = bpy.props.StringProperty() obj_layer_nr = bpy.props.IntProperty(default=3)obj_layer_nr = bpy.props.IntProperty(default=3) def execute(self, context):def execute(self, context): bpy.ops.object.select_all(action='DESELECT')bpy.ops.object.select_all(action='DESELECT') bpy.ops.import_scene.obj(filepath=self.filepath)bpy.ops.import_scene.obj(filepath=self.filepath) bpy.context.scene.objects.active = bpy.context.selected_objects[0]bpy.context.scene.objects.active = bpy.context.selected_objects[0] bpy.context.scene.objects.active.layers = layer(self.obj_layer_nr)bpy.context.scene.objects.active.layers = layer(self.obj_layer_nr) return {'FINISHED'}return {'FINISHED'}


Addition to GUI panel codeAddition to GUI panel code

def obj_fname_for_identifier(identifier):def obj_fname_for_identifier(identifier): fname = bpy.path.abspath('//occup_output/%s.obj' % identifier)fname = bpy.path.abspath('//occup_output/%s.obj' % identifier) return fnamereturn fname

… and in the draw() function, below the other button-drawing stuff:… and in the draw() function, below the other button-drawing stuff:

# OBJ load button# OBJ load button row = split.row(align=True)row = split.row(align=True) objfile = obj_fname_for_identifier(identifier)objfile = obj_fname_for_identifier(identifier) if os.path.exists(objfile):if os.path.exists(objfile): props = row.operator("import_mesh.obj", text="OBJ")props = row.operator("import_mesh.obj", text="OBJ") props.filepath = objfileprops.filepath = objfile


Converting to an addonConverting to an addon

● The previous code worked only in one Blender fileThe previous code worked only in one Blender file

✔Good enough for my useGood enough for my use

✔Easy to developEasy to develop

✗ Not good for distributionNot good for distribution

✗ Can't be used in multiple filesCan't be used in multiple files

● Solution: Solution: addonaddon


Converting to an addonConverting to an addon

● Toss everything into one Python file …Toss everything into one Python file …

● … … or one Python moduleor one Python module

● Add a Add a bl_infobl_info dict at the top dict at the top

● Add register/unregister functionsAdd register/unregister functions


bl_infobl_info

bl_info = {bl_info = { "name": "Bounding Circle Hierarchy","name": "Bounding Circle Hierarchy", "author": "Sybren A. Stüvel","author": "Sybren A. Stüvel", "version": (0, 1, 1),"version": (0, 1, 1), "blender": (2, 68, 0),"blender": (2, 68, 0), "location": "World properties -> Bounding Circle Hierarchies","location": "World properties -> Bounding Circle Hierarchies", "description": "Loads BCH data from a SQLite database","description": "Loads BCH data from a SQLite database", "warning": "Research code, may not always work.","warning": "Research code, may not always work.", "wiki_url": "http://wiki.blender.org/index.php/Extensions:2.6/Py/""wiki_url": "http://wiki.blender.org/index.php/Extensions:2.6/Py/" "Scripts/SybrensBCHLoader","Scripts/SybrensBCHLoader", "category": "Object""category": "Object"}}

Guidelines at: Guidelines at: http://wiki.blender.org/index.php/Dev:2.5/Py/Scripts/Guidelines/Addonshttp://wiki.blender.org/index.php/Dev:2.5/Py/Scripts/Guidelines/Addons


(un)registration(un)registration

def register():def register(): bpy.utils.register_class(BoundingCircles)bpy.utils.register_class(BoundingCircles) bpy.utils.register_class(LoadCircleHierarchy)bpy.utils.register_class(LoadCircleHierarchy) bpy.utils.register_class(LoadObjMesh)bpy.utils.register_class(LoadObjMesh)

def unregister():def unregister(): bpy.utils.unregister_module(__name__)bpy.utils.unregister_module(__name__)

# For easy testing:# For easy testing:if __name__ == '__main__':if __name__ == '__main__': register()register()


InstallationInstallation


RecapRecap

● We have seen how to:We have seen how to:– create objects from Pythoncreate objects from Python

– create operatorscreate operators

– extend the user interfaceextend the user interface

– obtain data from outside Blenderobtain data from outside Blender

– create an addoncreate an addon

● I hope you enjoyed it!I hope you enjoyed it!


My questions to youMy questions to you

● Setting parent object while keeping transformation matrixSetting parent object while keeping transformation matrix● Re-use of GUI elements?Re-use of GUI elements?● Custom property types?Custom property types?

– Object reference?Object reference?

● Custom editor type?Custom editor type?● Creating new objects in game engine?Creating new objects in game engine?


LinksLinks

● http://wiki.blender.org/index.php/Dev:2.5/Py/Scripts/Cookbohttp://wiki.blender.org/index.php/Dev:2.5/Py/Scripts/Cookbook/Code_snippets/Interfaceok/Code_snippets/Interface

● http://www.blender.org/documentation/blender_python_api_http://www.blender.org/documentation/blender_python_api_2_69_1/2_69_1/

● http://stuvel.eu/http://stuvel.eu/● http://stuvelfoto.nl/http://stuvelfoto.nl/● http://vhtlab.nl/http://vhtlab.nl/

blender as research tool · sybren a. stüvel - [email protected] blender as research tool: from...

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