Projected convex hull

projhull.py

 # ***** BEGIN GPL LICENSE BLOCK *****
 #
 # This program is free software; you can redistribute it and/or
 # modify it under the terms of the GNU General Public License
 # as published by the Free Software Foundation; either version 2
 # of the License, or (at your option) any later version.
 #
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
 # along with this program; if not, write to the Free Software Foundation,
 # Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 #
 # Contributor(s): Torbjörn Ratshman.
 #
 # ***** END GPL LICENSE BLOCK *****
 #


bl_info = {'name': 'Projected convhull', 'category': 'Object'}

import bpy
import bmesh
import mathutils
import pdb

class ProjectedConvhull(bpy.types.Operator):
	bl_idname='object.create_proj_convhull'
	bl_label='Create projected convex hull'
	bl_options={'REGISTER','UNDO'}
	plane_size_low_x=bpy.props.FloatProperty(name='Lower plane x radius',default=1,min=1e-6,max=1e6)
	plane_size_low_y=bpy.props.FloatProperty(name='Lower plane y radius',default=1,min=1e-6,max=1e6)
	plane_size_high_x=bpy.props.FloatProperty(name='Higher plane x radius',default=1,min=1e-6,max=1e6)
	plane_size_high_y=bpy.props.FloatProperty(name='Higher plane y radius',default=1,min=1e-6,max=1e6)
	height=bpy.props.FloatProperty(name='Column height',default=1,min=1e-6,max=1e6)
	n_planes=bpy.props.IntProperty(name='Number of cuts',default=10,min=2,max=100)

	def execute(self,context):
		pos_init=context.scene.cursor_location
		dz=(self.height-pos_init.z)/self.n_planes
		dsx=(self.plane_size_high_x - self.plane_size_low_x)/self.n_planes
		dyx=(self.plane_size_high_y - self.plane_size_low_y)/self.n_planes
		obj_sel=context.object
		objs=[]
		for k in range(0,self.n_planes):
		#Add plane
			pos=(pos_init.x,pos_init.y,pos_init.z + k*dz)
			bpy.ops.mesh.primitive_plane_add(location=pos,enter_editmode=True)
			bpy.ops.transform.resize(value=(self.plane_size_low_x + k*dsx,self.plane_size_low_x + k*dsx, 1.0))
			
		#Intersect with selected object
			bpy.ops.object.mode_set(mode='OBJECT')
			modifier=context.object.modifiers.new('Bool','BOOLEAN')
			modifier.operation='INTERSECT'
			modifier.object=obj_sel
			bpy.ops.object.modifier_apply(apply_as='DATA',modifier='Bool')
			
		#Compute 2d convex hull
			bpy.ops.object.mode_set(mode='EDIT')
			bpy.ops.mesh.extrude_region_move(TRANSFORM_OT_translate={'value':(0,0,1)})
			mesh=bmesh.from_edit_mesh(context.object.data)
			for v in mesh.verts:
				v.select = True
			bpy.ops.mesh.convex_hull(join_triangles=False,use_existing_faces=False)
			bpy.ops.mesh.select_all(action='DESELECT')
			for v in mesh.verts:
				if v.co.z > 0.5:
					v.select = True
			bpy.ops.mesh.delete()
			for v in mesh.verts:
				for f in mesh.faces:			
					if mathutils.geometry.intersect_point_tri_2d(v.co,f.verts[0].co,f.verts[1].co,f.verts[2].co) \
						and v!=f.verts[0] and v!=f.verts[1] and v!=f.verts[2]:
						v.select=True
			bpy.ops.mesh.delete()
			bpy.ops.mesh.select_all(action='SELECT')
			bpy.ops.mesh.edge_face_add()
			bpy.ops.mesh.select_all(action='DESELECT')
			bpy.ops.object.mode_set(mode='OBJECT')
			
		#Add result to list of objexts
			objs.append(context.object)
	
	#Join planes
		for obj in objs:
			obj.select=True
		bpy.ops.object.join()
		
	#Apply any transformation
		bpy.ops.object.mode_set(mode='OBJECT')
		bpy.ops.object.transform_apply(location=True)
		
	#Remove any double
		bpy.ops.object.mode_set(mode='EDIT')
		bpy.ops.mesh.select_all(action='SELECT')
		bpy.ops.mesh.remove_doubles()
	
	#Bridge edge loops
		bpy.ops.mesh.bridge_edge_loops()

	#Remove interior faces
		bpy.ops.mesh.select_all(action='DESELECT')
		bpy.ops.mesh.select_interior_faces()
		bpy.ops.mesh.delete(type='FACE')
				
		return {'FINISHED'}

	def invoke(self, context, event):
		wm = context.window_manager
		return wm.invoke_props_dialog(self)

	@classmethod
	def poll(cls, context):
		if context.object is not None:
			return context.object.type=='MESH'
		return 0
		
def register():
	bpy.utils.register_class(ProjectedConvhull)
	bpy.types.VIEW3D_MT_object.append(menu_func)

def unregister():
	bpy.utils.VIEW32_MT_object.remove(menu_func)
	bpy.utils.unregister_class(ProjectedConvhull)
	
def menu_func(self, context):
	self.layout.operator(ProjectedConvhull.bl_idname)

if __name__=='__main__':
	register()