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    Welcome!

    This is the community forum for my apps Pythonista and Editorial.

    For individual support questions, you can also send an email. If you have a very short question or just want to say hello — I'm @olemoritz on Twitter.


    3D in Pythonista?

    Pythonista
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    • zencuke
      zencuke last edited by

      If you can draw 2D you can always do 3D drawing. Unless you mean 3D printing 3D drawing is done by projecting the 3D onto 2D and drawing the result. After all computer/cell phones only have 2D screens. That being said there is a lot of math involved and it is nice to be able to use a library to handle it for you. Now that NumPy has been ported it shouldn't be hard to port one of the 3D graphics packages.

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      • zencuke
        zencuke last edited by

        Additional note: What is hard in 3D graphics isn't the geometry, it is rendering, i.e. coloring the surfaces. Dooms biggest trick was to require all objects/walls to be perpendicular to the viewer. That simplified the rendering requirements substantially. Essentially every object in doom was a 2D shape with an image drawn on it. You scale to represent distance.

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        • Webmaster4o
          Webmaster4o last edited by

          Are there any 3D libraries out there that could be made to work with numpy/PIL?

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          • Moe
            Moe last edited by

            Take a look at SceneKit. While there is no python wrapper for it, you could use objc_util to accomplish that. It would probably make your life easier if you were to make a python wrapper first. To load that framework use

            from objc_util import *
            
            ObjcClass('NSBundle').bundleWithPath_('System/Library/Frameworks/SceneKit.framework').load()
            
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            • omz
              omz last edited by omz

              If you want to play with SceneKit, here's a starting point (requires beta #160023):

              Screenshot

              Note: You can use gestures (pan/pinch) to control the camera.

              from objc_util import *
              import ui
              import math
              
              load_framework('SceneKit')
              SCNView, SCNScene, SCNBox, SCNText, SCNNode, SCNLight, SCNAction, UIFont = map(ObjCClass, ['SCNView', 'SCNScene', 'SCNBox', 'SCNText', 'SCNNode', 'SCNLight', 'SCNAction', 'UIFont'])
              
              class SCNVector3 (Structure):
              	_fields_ = [('x', c_float), ('y', c_float), ('z', c_float)]
              
              @on_main_thread
              def demo():
              	main_view = ui.View()
              	main_view_objc = ObjCInstance(main_view)
              	scene_view = SCNView.alloc().initWithFrame_options_(((0, 0),(400, 400)), None).autorelease()
              	scene_view.setAutoresizingMask_(18)
              	scene_view.setAllowsCameraControl_(True)
              	scene = SCNScene.scene()
              	root_node = scene.rootNode()
              	text_mesh = SCNText.textWithString_extrusionDepth_('Pythonista', 6.0)
              	text_mesh.setFlatness_(0.2)
              	text_mesh.setChamferRadius_(0.4)
              	text_mesh.setFont_(UIFont.fontWithName_size_('HelveticaNeue-Bold', 18))
              	bbox_min, bbox_max = SCNVector3(), SCNVector3()
              	text_mesh.getBoundingBoxMin_max_(byref(bbox_min), byref(bbox_max), restype=None, argtypes=[POINTER(SCNVector3), POINTER(SCNVector3)])
              	text_width = bbox_max.x - bbox_min.x
              	text_node = SCNNode.nodeWithGeometry_(text_mesh)
              	text_node.setCastsShadow_(True)
              	text_container = SCNNode.node()
              	text_container.addChildNode_(text_node)
              	text_container.setPosition_((0, 40, 0))
              	text_node.setPosition_((-text_width/2, 0, 0))
              	box = SCNBox.boxWithWidth_height_length_chamferRadius_(100, 4, 100, 1)
              	box_node = SCNNode.nodeWithGeometry_(box)
              	root_node.addChildNode_(box_node)
              	rotate_action = SCNAction.repeatActionForever_(SCNAction.rotateByX_y_z_duration_(0, math.pi*2, math.pi*2, 10))
              	text_container.runAction_(rotate_action)
              	root_node.addChildNode_(text_container)
              	light_node = SCNNode.node()
              	light_node.setPosition_((0, 100, 10))
              	light_node.setRotation_((1, 0, 0, -math.pi/2))
              	light = SCNLight.light()
              	light.setType_('spot')
              	light.setCastsShadow_(True)
              	light.setColor_(UIColor.cyanColor().CGColor())
              	light_node.setLight_(light)
              	root_node.addChildNode_(light_node)
              	scene_view.setScene_(scene)
              	main_view_objc.addSubview_(scene_view)
              	main_view.name = 'SceneKit Demo'
              	main_view.present()
              
              demo()
              
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              • Utsira
                Utsira last edited by

                Apologies for bumping a 2-year-old thread. When I try to run the above script in Python 3.5 I get an error at the map command saying:

                no Objective-C class named 'b'SCNView'' found

                Is this some 2.7 -> 3.5 issue? What is the extraneous 'b in the error message referring to?

                thanks in advance.

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                • ccc
                  ccc last edited by

                  The b'bytes string' is https://docs.python.org/3/reference/lexical_analysis.html#grammar-token-bytesprefix

                  SCNView is https://developer.apple.com/reference/scenekit/scnview

                  But I know nothing more.

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                  • omz
                    omz last edited by

                    Try adding load_framework('SceneKit') before the line with the error.

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                    • abcabc
                      abcabc last edited by abcabc

                      Thanks Omz . I tried also the basic code from following tutorial using your template and it is working fine.
                      https://code.tutsplus.com/tutorials/an-introduction-to-scenekit-fundamentals--cms-23847

                      from objc_util import *
                      import ui
                      import math
                      
                      load_framework('SceneKit')
                      
                      SCNView, SCNScene, SCNBox, SCNText, SCNNode, SCNLight, SCNCamera, SCNAction, UIFont = map(ObjCClass, ['SCNView', 'SCNScene', 'SCNBox', 'SCNText', 'SCNNode', 'SCNLight',  'SCNCamera', 'SCNAction', 'UIFont'])
                      
                      class SCNVector3 (Structure):
                          _fields_ = [('x', c_float), ('y', c_float), ('z', c_float)]
                          
                      '''
                      https://code.tutsplus.com/tutorials/an-introduction-to-scenekit-fundamentals--cms-23847
                      '''
                      '''
                      override func viewDidLoad() {
                          super.viewDidLoad()
                           
                          let sceneView = SCNView(frame: self.view.frame)
                          self.view.addSubview(sceneView)
                               
                          let scene = SCNScene()
                          sceneView.scene = scene
                       
                          let camera = SCNCamera()
                          let cameraNode = SCNNode()
                          cameraNode.camera = camera
                          cameraNode.position = SCNVector3(x: 0.0, y: 0.0, z: 3.0)
                       
                          let light = SCNLight()
                          light.type = SCNLightTypeOmni
                          let lightNode = SCNNode()
                          lightNode.light = light
                          lightNode.position = SCNVector3(x: 1.5, y: 1.5, z: 1.5)
                       
                          let cubeGeometry = SCNBox(width: 1.0, height: 1.0, length: 1.0, chamferRadius: 0.0)
                          let cubeNode = SCNNode(geometry: cubeGeometry)
                       
                          scene.rootNode.addChildNode(lightNode)
                          scene.rootNode.addChildNode(cameraNode)
                          scene.rootNode.addChildNode(cubeNode)
                      }
                      '''
                      
                      @on_main_thread
                      def demo():
                          main_view = ui.View()
                          main_view_objc = ObjCInstance(main_view)
                          scene_view = SCNView.alloc().initWithFrame_options_(((0, 0),(400, 400)), None).autorelease()
                          scene_view.setAutoresizingMask_(18)
                          scene_view.setAllowsCameraControl_(True)
                          main_view_objc.addSubview_(scene_view)
                          main_view.name = 'SceneKit Demo'
                          
                          scene = SCNScene.scene()
                          scene_view.setScene_(scene)
                          
                          root_node = scene.rootNode()
                          
                          camera = SCNCamera.camera()
                          camera_node = SCNNode.node()
                          camera_node.setCamera(camera)
                          camera_node.setPosition((0.0, 0.0, 3.0))
                      
                          light = SCNLight.light()
                          light.setType_('omni')
                          light_node = SCNNode.node()
                          light_node.setLight_(light)
                          light_node.setPosition((1.5, 1.5, 1.5))
                          
                          cube_geometry = SCNBox.boxWithWidth_height_length_chamferRadius_(1, 1, 1, 0)
                          cube_node = SCNNode.nodeWithGeometry_(cube_geometry)
                          
                          root_node.addChildNode_(light_node)
                          root_node.addChildNode_(camera_node)        
                          root_node.addChildNode_(cube_node)
                          
                          main_view.present()
                      
                      demo()
                      
                      
                      
                      

                      Full example here
                      https://gist.github.com/balachandrana/644840a223b636ecd84d14a595dad33b

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                      • Utsira
                        Utsira last edited by

                        @omz thanks, it works now, that's awesome. I've used SceneKit quite a lot with Swift, but I'm still new to Python/ Pythonista. One question, how come you implement SCNVector3 as a Python class, rather than importing it with the other ObjC classes? Just trying to understand the implications of working with ObjC libraries in Pythonista. thanks.

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                        • dgelessus
                          dgelessus last edited by

                          SCNVector3 is a C struct, not an Objective-C class. Objective-C classes carry lots of information at runtime (their name, superclass, protocols, methods, etc.), and all Objective-C objects contain a pointer to their class. All of this information can be looked up via APIs provided by the Objective-C runtime library. That's what makes objc_util possible.

                          C structs, on the other hand, carry no runtime info at all. If you look at some struct data, you cannot see what its type is. For all you know, it might not even be a struct. It could also be an int, or an array of bytes. There is also no way to see what struct types there are, or what fields a certain struct type has.

                          So to be able to work with struct data, you first need to describe its type. In ctypes, you do that by creating a subclass of the ctypes.Structure class. Your subclass's _fields_ attribute lists the name and type of every field in the struct. Once you've done that, you can allocate instances of your struct in memory, and you can tell ctypes that a function takes or returns struct data of that type.

                          In this specific case, I don't think the declaration of SCNVector3 is actually needed. In the above code, you can see that all places where a SCNVector3 would be used in Swift, the Python/objc_util version simply uses a tuple. This is only possible because Objective-C is involved. All Objective-C methods have a type signature, which describes the types of their return value and all arguments, including structs. This allows objc_util to get some basic info about a method's struct arguments, which is enough to convert a Python tuple into correctly formated C struct data. This only works with Objective-C method arguments though, and not anywhere else. For plain C functions and variables, you still need to declare the struct type by hand.

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                          • Utsira
                            Utsira last edited by

                            Thank you for your answer @dgelessus , really interesting.

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                            • bcraig_6973
                              bcraig_6973 @JadedTuna last edited by

                              @JadedTuna
                              I am new to this
                              Have you got a better Handel on how to do this
                              All I want to do is just using 3 Python learn to how create a 2d flat grid in 3d space
                              What are the step by steps to do this kind of thing ?

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                              • Brun0oO
                                Brun0oO last edited by Brun0oO

                                Hi,

                                I got, from a swift project, some SceneKit assets (files with ‘.scn’ extension). I put them in a ###.scnassets directory and try to load them using the SCNScene.sceneNamed_ method.
                                This call fails, i got None as result.
                                Do you know if I need to make a kind of initialization for the SceneKit resources mechanism ?

                                Thanks for your help...

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