Example for a Post-Processing script for 3D-Import (Collada)

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Example for a Post-Processing script for 3D-Import (Collada)

wombatstampede

The intent of this post is to show how helpful the post-processing function of the 3D import can be.

Here's the basic reference: http://docs.godotengine.org/en/stable/learning/features/3d/importing_3d_scenes.html

What you can't to with post-processing: - You can't change much on the update-policy. Godot decides what objects are overwritten/recreated when re-importing updated models. - You can't access any objects/data which the Godot import didn't import.

What you can do: - You can add/remove and update any object of the imported 3d scene after the import was completed. - You can use any other GDScript functions (write to files etc.) - You can decide whether the import was successful or not.

This example deals with auto-creating collision box shapes for walls an other boxes. It can auto-create shapes when the surface was assigned a specific material which name contains "-collide". It can auto-create boxshapes inside other physics objects (-colonly and -rigid) when the box contains the name "-colbox". It can initialize physics objects with specific values for i.e. layer & mask when the scene contains an object with "-preset" in its name.

This script is a kind of specialized. But perhaps it serves as an "inspiration" for you to create your own post-processing scripts.

Here's an example 3d-scene in Blender: Note the material name "LockWall-collide" or the "#preset..." and "-rigid", "-colbox" objects in the object tree.

Here's the result after import + post-process in Godot:

The script is in the next post. (Post limit)

wombatstampede

Here's the script:

tool
extends EditorScenePostImport

var mdt
var preset={}
var presetMatch

func post_import(_scene):
	mdt = MeshDataTool.new()
	presetMatch = RegEx.new()
	presetMatch.compile("-(\\w+)=(-?[0-9.]+)")
	
	getCollisionNode(_scene,_scene)
	
	print ("*** done ***")
	return _scene
	
func getCollisionNode(node,scene):
	var delList = {}
	for N in node.get_children():
		if N.get_child_count() > 0:
			#print("["+N.get_name()+"]")
			getCollisionNode(N,scene)
		if N.is_type("CollisionObject"):
			setBodyPresets(N)
		#print(" "+N.get_type())
		
		# build collision shapes "box" for "walls" when material contains "-collide" flag in name
		# * mesh has to consist of tris (check on blender collada export)
		# * "wall" surface "quad" consists of 2 tris
		# * "bottom" tri is required to have 2pts of equal height (y-value)

		if (N.get_type()=="MeshInstance"): 
			var has_collide = false
			var m = N.get_mesh()
			for s in range(0,m.get_surface_count()):
				if (m.surface_get_name(s).find("-collide")>=0):
					if m.surface_get_primitive_type(s) == Mesh.PRIMITIVE_TRIANGLES:
						has_collide=true
					else:
						print("Error: wrong surface type "+String(m.surface_get_primitive_type(s))+
								" for "+m.surface_get_name(s)+". Required: PRIMITIVE_TRIANGLES")
					
			if has_collide: #collide material found
				var cscount=0
				
				delList[N.get_name()+"_collision"]="StaticBody"
				var sb=StaticBody.new()
				sb.set_name(N.get_name()+"_collision")
				N.add_child(sb)
				sb.set_owner(scene)
				setBodyPresets(sb)
				
				#PRIMITIVE_TRIANGLES = 4
				
				for s in range(0,m.get_surface_count()):
					if (m.surface_get_name(s).find("-collide")>=0): 
						var newname=m.surface_get_name(s).replace("-collide","")
						
						mdt.create_from_surface(m, s)
						for f in range(mdt.get_face_count()):
							var v=[]
							var cwid = 0.5 #width of collision shape (away from normal)
							for vc in range(3):
								v.append(mdt.get_vertex(mdt.get_face_vertex(f,vc)))
							var minY=min(v[0].y,min(v[1].y,v[2].y))
							var maxY=max(v[0].y,max(v[1].y,v[2].y))
							var vxz=[]
							for vc in range(3): #make array of 2 verts at minY
								if abs(v[vc].y-minY)<0.01:
									vxz.append(v[vc])
							if vxz.size()==2: #not "upper rectangle" (which has only 1 vert at minY)
								var norm=mdt.get_face_normal(f)
								#y-values are the same so this is length in xz plane
								var xzVec=vxz[1]-vxz[0]
								var lenxz=xzVec.length()
								var midxzOffs=xzVec/2
								var cshape = CollisionShape.new()
								var bshape = BoxShape.new()
								#node.add_shape(bshape,N.get_transform())
								cscount=cscount+1
								cshape.set_name(newname+"_"+String(cscount))
								cshape.set_shape(bshape)
								sb.add_child(cshape)
								#you need to set_owner to scene root to make a node visible in editor
								cshape.set_owner(scene) 
								bshape.set_extents(Vector3(cwid/2,(maxY-minY)/2,lenxz/2))
								#center of new shape
								cshape.set_translation(Vector3(vxz[0].x+midxzOffs.x-(norm.x*(cwid/2)),
										minY+((maxY-minY)/2),vxz[0].z+midxzOffs.z-(norm.z*(cwid/2))))
								
								cshape.rotate_y(Vector2(xzVec.x,xzVec.z).angle_to(Vector2(0,-1)))
								
						mdt.clear()
		
		# Create collision shape for a box-object inside a -colonly (StaticBody) or -rigid (RigidBody) parent
		# * object name contains "-colbox"
		# * client object rotation is not transferred (if any)
		# * shape has extents and position of box
		# * removes automatically created shapes ("shape","SphereShape","BoxShape")
		if (N.get_type()=="MeshInstance") and (N.get_name().find("-colbox")>=0): 
			print(node.get_name()+" ->"+N.get_name())
			var newname=N.get_name().replace("-colbox","")
			
			if node.is_type("CollisionObject"): #parent can deal with collision shapes
				print(" is collision")
				
				var aab=N.get_aabb()
				var cshape=null
				var bshape=null
				#reuse/update shape if already exists, does this ever happen?
				if node.has_node(newname) and (N.get_type()=="CollisionShape"):
					cshape = node.get_child(newname)
					bshape = cshape.get_shape()
					print(" update existing")
				else:
					cshape = CollisionShape.new()
					bshape = BoxShape.new()
					#node.add_shape(bshape,N.get_transform())
					cshape.set_name(newname)
					cshape.set_shape(bshape)
					node.add_child(cshape)
					#you need to set_owner to scene root to make a node visible in editor
					node.get_node(newname).set_owner(scene) 
					#cshape.set_owner(node) #required? think not
				bshape.set_extents(aab.size/2)
				#no rotation transferred
				print("Pos: "+String(aab.pos)+" End: "+String(aab.end))
				#pos + size/2 seems to work good as long as pos is min of (pos,end)
				#todo: move basis/rotation over
				cshape.set_translation(N.get_translation()+((aab.pos+(aab.size/2))))
				node.remove_child(N) #maybe not required when free/queue_free is used
				N.queue_free()
				
				#remove shapes which are auto-added to rigidbodies(-rigid)/staticbodies (-colonly)
				#they're replaced by colbox shapes
				delList["shape"]="CollisionShape"
				delList["SphereShape"]="CollisionShape"
				delList["BoxShape"]="CollisionShape"
				
		#Objects with -preset in name allow to initialize selected presets (i.e. for RigidBody/StaticBody)
		#Example name: "Cube-preset-mask=1024-layers=3-mass=1000"
		if (N.get_type()=="MeshInstance") and (N.get_name().find("-preset")>=0): #preset values
			#print("get presets")
			presetMatch.find(N.get_name())
			
			var matchStart=0
			var prevMatchStart=0
			while presetMatch.find(N.get_name(),matchStart)>=0:
				matchStart=presetMatch.get_capture_start(0)+presetMatch.get_capture(0).length()
				if prevMatchStart==matchStart:#check for endless loop
					print("error in regexpmatch endless loop")
					break
				else:
					prevMatchStart=matchStart
					
				preset[presetMatch.get_capture(1)]=presetMatch.get_capture(2)
				print("preset: "+presetMatch.get_capture(1)+"<=>"+presetMatch.get_capture(2))
				delList[N.get_name()]=null
	#delete child nodes after iteration (to not confuse object iteration)
	for i in delList:
		delchild(node,i,delList[i])

#init selected presets if set
func setBodyPresets(node):
	if node.is_type("PhysicsBody") or node.is_type("Area"):
		if preset.has("mask"):
			node.set_collision_mask(int(preset["mask"]))
		if preset.has("layers"):
			node.set_layer_mask(int(preset["layers"]))
	if node.is_type("RigidBody"):
		if preset.has("mass"):
			node.set_mass(float(preset["mass"]))
		if preset.has("friction"):
			node.set_friction(float(preset["friction"]))
		if preset.has("linear_damp"):
			node.set_linear_damp(float(preset["linear_damp"]))
		if preset.has("angular_damp"):
			node.set_angular_damp(float(preset["angular_damp"]))

func delchild(node,childid,type=null):
	if node.has_node(childid):
		var c=node.get_node(childid)
		if (type==null) or (c.get_type()==type):
			node.remove_child(c)
			c.queue_free()