TRACK TO CONSTRAINT

 

When we talk about constraints we talk about a source/owner and the target object. Constraint is applied to the source object. The source object, when it has to pickup  the control parameters from another object, then a target object is added. Some constraints of this type are transformation constraint, action constraint, copy location/rotation/scale constraint. Some  constraints which do not require a target object are limit location, limit distance, limit rotation and so on.

 Track to constraint, in simple terms means  a "Look at"  sort of constraint. When you have an object say a monkey(target) and the camera (source) on which the constraint is applied, the camera is set to face the monkey, irrespective of the movement or rotation of the Monkey or the camera. If the "Up" and "To" axis setting is the same, the constraint will not work. The influence setting can vary from 0 to 1. Zero means no effect, 1 means maximum effect.

 

The three images above shows how the Camera is always facing the Monkey.

The settings to activate the Track-to constraint is shown above. Some other examples of using this constraint are given below:

1. Let us say a ball is bouncing across the ground and the player's eye balls are continuously following the ball, then the constraint  is applied to the eye ball with the ball as the target.

2. Let us say a singer is moving around on the stage and a focus light is set such that the light beam always follows the singer, then the target will be the  singer and the constraint will be applied on the light(source/owner).

Experiment with the settings to get a hang of how it works.

CONSTRAINTS

 Constraints are a way to control an object’s  location, rotation or scale. Constraints can be used on objects or bones.Constraints are  mainly  used in animation. It can also be used on objects for controlling in a static sense. While constraints are used on the object as a whole it can also be used to control a vertex group or a bone part.
 

To apply a constraint to an object(or bone), first select it.

Constraints can be activated from the Properties panel  by clicking on the button having two chain links as its image icon. Hovering the cursor over this icon will display its name.

 When you have an object in the 3D window, constraints can be  activated by going to the header bar which is below the 3D windows, clicking on Object ->Constraints-> "Add constraints with target".  Keyboard shortcut for this is Shift+Ctrl+C. This will open the constraints menu panel. Here click on the particular constraint. This will open the particular constraint's menu window where required setting should be made to  activate the constraint. 

 More than one constraint can be applied to an object which is known as cascading constraints. All the constraints from top to be one below till the last one will have its effect on the object. 

 A constraint when applied to an object may be temporarily deactivated by clicking on the eye icon in the constraint window, to closing it. 

 Further the influence setting which has a value varying from 0 to 1 can be animated. Setting the influence value to zero will also deactivate  constraint.

TO SHIFT ORIGIN OF AN OBJECT TO ANY POINT

 

Origin of an object can be shifted  to any point on the object or outside it.

 

TO SHIFT ORIGIN OF AN OBJECT TO ANY POINT ON THE OBJECT

 Follow the steps given below:

1 Select the object and go to edit mode by pressing Tab key.

2. If all the vertices are selected, press  "A" key to de select all vertices.

3. Click on the desired vertex on which the Origin needs to be positioned and go to Mesh-> Snap->Cursor to selection.

4. Press Tab key to go to object mode. Now press Object->Transform-> Origin to 3D Cursor.

TO SHIFT ORIGIN OF AN OBJECT TO ANY POINT OUTSIDE THE OBJECT.

1. Let us consider a Cube for this example.

2. Select Cube and press Tab key to go to  Edit mode. 

3. Select all the vertices, including the ones hidden from your direct view.

4. Assume that we want the Origin to be 3 Blender units away from the geometric Centre of the cubes. Press G-> X-> 3 and hit Enter key.

 

ADD ONS

 Add-ons are scripts which are written to be used with Blender to achieve additional or special functionalities which are not coming with the core -Blender software.  Add-ons are grouped into Official, Community or Testing.

1. Official  add-ons are  provided with Blender, but needs to be enabled.

2. Add-ons which come under the Community are developed by the Blender community members. These add-ons generally needs to be downloaded from the web, and installed and then enabled to make it usable.

3. Add-ons coming under the Testing group are mostly developed by community members by still under test for performance with out any glitch.

To access Add-on set up in Blender follow the following path. File->User Preferences->   Add-Ons and enable the desired Add-on in the list provided below and click on Save User settings to save the  enable setting of the add-on, just done by you.

TO COPY NODE TREE FROM ONE OBJECT TO ANOTHER.

Assume that you you have made a node tree to set up a new material for an object(Let us say an UV Sphere). Now you add  another object (let us say a Cube). To copy the node tree from UVSphere to the Cube follow these simple steps:

1. Select the UVSphere. In the node editor set up a simple material node tree and save it. Now select all the nodes using Box select option. To copy these node tree to clip board click on the first floppy disk (like icon in light yellow color on the menu bar of the node editor.

2. Select the Cube,click on new material and click on new. You will see a Diffuse BSDF node connected to the Material Output node.Click inside the node editor window using LMB. Now click on the floppy disk icon on the right side. The node tree of the UVSphere will be pasted here. Select the 3D window  and press Shift+Z to see the rendered view of both objects with the new material. Change in material setting of the nodes of UVSphere does not affect the material settings of the Cube.

IMAGE BASED LIGHTING (IBL)

  This learning material for Image Based Lighting (IBL) is written as applicable to Blender Version 2.79b. Image based lighting setup  is done using cycles node, with render Engine set to Cycles. Download and keep an HDRI image ready for use as the background Image.

Now the steps are as follows:

1. Set up a basic scene with a Cube  as the main object and a plane below it to serve as the ground. Add material and texture to both the Cube and Plane using cycles nodes. 

2. Change the lamp to Sun and set  strength to 3. Rotate it to direct its light ray on to the Cube.

3. Set the Camera and hit  0 (zero) key in Number pad to go to camera view. Adjust its position and direction to get desires view. 

4. In the properties Panel in the right, select World settings. Go to surface panel and for Surface select Background. 

5. Split the 3D window into three windows. Two at the top and the third one below. The top left window may be used to see the rendered view(Shift+Z), the top right window to see the 3d view and the window opened below may be used as a Node editor. 

6. In the Node Editor window, select World  for World setting. 

7. Add three nodes -  Environment texture, Background node and World Output node from left to right. Connect Color in Environment Node to Color in Background Node and from Background   here to Surface in World Output Node. Now the background would turn to a pink Color in the Rendered view, which indicates that all your node setting are ready for IBL. 

8. In the Environment Texture Node go to Open File option and open the HDRI image file. Now you will be able to see the image on the HDRI image file as the background in your scene. To see the rendered scene, hit Shift+Z in the top left window which we had opened for seeing the rended output.

9. If you want see the rendered image in full screen, first click inside the top left window and then press Shift + Space Bar. To go back to previous view hit Shift+Space bar key again. It toggles between the two view modes.

ANIMATION

 ANIMATION-2

ADDITIONAL FEATURES

 Here we shall learn about some additional  features of animation in Blender. When we want to animate a character(say a Cube), apart from changing its location, its angle of rotation and size(scaling) can also be animated. Again combinations like location and rotation, location and size,rotation and size or all three location-rotation-scale can be varied. Further these changes can be effected on all three axes - X,Y and Z.
 Further not only the objects in Blender like the Cube, Cylinder,Cone, UVSphere can be animated, the Camera and Lights can also be animated .  Further, the different shades of colour of an object or the brightness level can also be animated.  
 If there are more than one object in the 3D Screen, when we animate, we must set key frames for each Object. Again when the movement of the object is complex, (when we make a robot to walk like a man) then the number of keyframes would also increase very fast. This can be a very daunting task. To simplify the keyframing process and to speed it up, we can use Auto keyframing.

BLENDER ANIMATION

 ANIMATION 1 -INTRO

The word "Animation" is derived from the word "Animate" , which means to make an object come alive or to move like a living being. Cartoon characters are a good example of animation where the characters are made to walk, jump,slide,laugh or do  any other motion.


ANIMATION CONCEPT

Let us understand the basic concept of animation. Look at the image of an arrow facing upwards in Fig-1. 

                                                      Fig-1


We want this arrow to smoothly turn to the horizontal position as shown in Fig-2.

 Fig-2

To animate this arrow, we draw images of the arrow at in-between positions as shown in Fig-3.

                                                                         Fig-3

 The whole set of image, from beginning to end,  would then be as shown below in Fig-4.

                                               Fig-4


When we animate these images the computer will generate images for all in-between positions and show all the images in  sequence. The arrow will appear to turn smoothly from Vertical to Horizontal position as shown in the video, whose link is given below:

https://drive.google.com/file/d/1krmBTsjkgH9fgMNc59FPzZn7MZxIsxkb/view?usp=sharing

 In animation, one basic idea we must know is that when a sequence of images are run quickly at a minimum rate of 24 images per second the human eye sees the image movement  as a continues movement. This   idea is used in all animation, videos and movies.

 In Blender each of this image, where some change is made, is called  a Keyframe. We must set the key frames in Blender. In the Arrow animation example we discussed above, we have set four keyframes.  When we animate, Blender generates all the intermediate frames.

Now we shall learn to animate a Cube in Blender. The steps are given below:

1. Open Blender and then a new file and add an object(Cube)  at x,y location(0,0) in the Top view(Press Numpad 7).
2. In the Timeline window as shown below, set the frame number to 1.

2. Position the cursor in 3D window and press "I" key. In the "Insert keyframe Menu" panel which opens, select "Location".

 

 

An yellow line will appear in the Timeline window which indicates that a key frame is inserted.

3. Next set the frame number to 125 in the Timeline window as shown below. 

 

In the 3D window move the cube to x,y location (5,5). Hit "I" key, then select Location in the "Insert Keyframe Menu" panel. An yellow line will appear in the time line window which indicates that a key frame is inserted at frame 125.

4. Next set the frame number to 250 in the Timeline window as shown below.

 

In the 3D window move the cube to x,y location (10,10). Hit "I" key, then select Location in the "Insert Keyframe Menu" panel. An yellow line will appear in the time line window which indicates that a key frame is inserted at frame 250.
5. Now set the frame number to 1 by pressing |<< key in the TimeLine window. This can also be done by entering 1 in the window as shown in the image above. To play the animation, press > key.
6. Save the Blender file.

ARRAY MODIFIER

 TO CREATE MULTIPLE OBJECTS OF THE SAME TYPE(BLENDER 2.79b)

 If you want to create, let us say 10 cubes of the same size , placed side by side with some spacing between the cubes Array modifier can be used.
 

  First open the 3D window and a cube.To active the Array modifier, go to the Properties window and clip on the spanner icon.A window with a  heading "Add Modifier" will appear. It has a drop down menu with a number of modifier options. Under the Generate heading click on "Array" to open the Array modifier option. In the window which opens, set count to 10 and under the Relative option, against x axis set it to 1.1 . Then click on Apply button to create an Array of 10 cubes.

 You can try out different settings by varying the count setting, and offset settings. Similarly set the offset along Y or Z axis and  see the result.For more details on Array modifier, see some video tutorial on the subject.

 Once the array is created, go to edit mode and hit "P" key and then click on Separate  by loose parts. Then go to object mode,select all the cubes and click on Ctrl+Shift+Alt+C to move the origin to the centre of each cube. Now each cube can be moved separately. Before you did this, all the cubes would move together.

Array modifier can be used to create a row of cubes(any object), which we may define as 1X5 for a row of 5 cubes in one row. Two dimension layout of cubes can also be created, which we may define as 5x5 and three dimension can be defined as 5x5x5.

To create a 2D array of say 5x5, first create an array of 5 cubes. Select all the 5 cubes, again open Array modifier set the count to 5 and the offset against y axis as 1.1 and click on Apply button.

To create a 3D array, select all the 25 cubes created above, set count to 5 and the offset against Z axis to 1.1 and click on Apply button.

SAMPLE WORKS DONE WITH BLENDER

Image-Animation2 Some of the art work created with blender are made available for viewing.The links for the same are provided below. Click on the  link  to  see/play the image/video.

HEXAGON ANIMATION

TWO-SPHERES

CUBES-GRID ANIMATION

QUADCOPTER-GENERIC 6 DOF CONSTRAINT

BALL-LAMP -TRACK TO CONSTRAINT

CAR ANIMATION-GENERIC 6 DOF CONSTRAINT

GEARS ANIMATION -COPY ROTATION CONSTRAINT

 DUPLIVERTS-ANIMATION

ELECTRON-SPIN

DUPLIVERTS-PLANES 

DUPLIVERTS-ICOSPHERE 

DUPLIVERTS-ICOSPHERES1 

PARTICLES SIMULATION 

PARTICLES-ASTRO-SIM1 

PARTICLES-ASTRO-SIM2

Thermo-Electric 

DNA-HELIX

Scientific Visualization

Scientific Visualization-3

Scientific Visualization-4

Scientific Visualization-5-Magnetic Field

Scientific Visualization-6-Graphene Tube

Scientific Visualization-7-Galaxy

Multiple Gears Animation

 Drones

Swarm Drones 

Image Animation 

Cubes Animation 

Image Animation 2

SCRIPT TO DELETE ALL OBJECTS IN 3D WINDOW

Script to delete all objects in 3D window:

import bpy


bpy.ops.object.select_all(action='TOGGLE')
bpy.ops.object.delete(use_global=False)

BPY SCRIPT TO ADD A CUBE AND A MATERIAL TO IT

The following script can be used  to add  a cube and a material to it:

 

import bpy

bpy.ops.mesh.primitive_cube_add(location=(0,0,0))
obj_matl=bpy.data.materials.new("obj_clr")
obj_matl.diffuse_color=(1,0,0)
mesh=bpy.context.object.data
mesh.materials.append(obj_matl)

GETTING YOUR FEET WET

 EDIT MODE

Open a new 3D window, change to front view by clicking on "1" key (in number pad), hit Shift+C to move the cursor to the 3D origin. Press Shift+A to add an object, then go to Mesh and then click on Cube. A cube object will be added. Press Tab key to go to edit mode, press "A" key to deselect all.

To select a vertex click RMB on it. If you  want to select another vertex also, hold the Shift key down and then keep the cursor on the second vertex and then press RMB.

If you want to select an edge, first click on the edge select button in the horizontal panel in the bottom.It is positioned to the right of the edit mode  button. Then position the cursor on the edge you want to select and press RMB.

TO select a face, first select the face select option then select the face in a similar way.



SAVING FILE IN BLENDER

In Blender, the file you are working on must be saved when ever some substantial change is done in your file. Blender DOES NOT auto-save your file. Choose the proper directory where your Blender files are saved. Blender files are saved with the extension ".blend".


DUPLICATING AN OBJECT

To duplicate an object, select the object in object mode, press Shift+D.Then move the mouse, the duplicated object will move in the direction of the mouse movement. Click LMB to confirm the location of the duplicate  object.


STEPS FOR PROPER WORK FLOW

When you want to create a simple object (like a metallic bowl)  or a more complex one,it is worthwhile to spend some time to plan your steps to achieve the desired result. Working as you think would not help you move forward in a focused manner. "Set a target . Achieve it" This would be a better approach.

 
Basic steps for a proper work flow are listed below. You may adapt it to your specific needs:

1. Make a pencil sketch of the model you want to create.
2. Think of the tools in Blender which you would use to design your model.
3. Create the mesh of your model.
4. Add material.
5. Add texture..
6. Add light.
7. Set world horizon colour, if you want.
8. Position camera to get a good view of your model.
9. Render the image.
10.Save results.


CAMERA VIEW

If you want to set the camera position to a desired view which you have already got on your 3D screen, press Ctrl+Alt+0 (Zero key on Number pad).

 

EXTRUDING IN BLENDER

To extrude a set of vertices, select them using Box select option, then press "E" key then "z" key to extrude along z axis. Once you have extruded to desired length, click LMB to confirm.

EDIT MODE IN BLENDER

 14/10/2020

EDIT MODE

An object in Blender in the edit mode is defined by its vertices, edges and faces. If we consider a square plane, it has four vertices at the four corners,four lines(called as edges in Blender) connecting these four vertices and a  surface (called face in Blender) which stretches between the four edges.

Similarly if we consider a Cube it has 8 vertices, 12 edges and 6 faces. These details of the plane and cube are shown in the image below:

An UVSphere in edit mode would like this:

Thus we may conclude that all objects are constructed using vertices,edges and faces. The same  process is used for making both simple mesh like a cube or to construct more complex shapes which may go up to construct a human body shape or a complex machine part like a bolt, a gear wheel.

A bolt in mesh mode is shown below:

WORKING IN EDIT MODE

To work in edit mode, first open a 3D window in Blender, and add an object like a Cube.Hit Tab key go to edit mode.In edit mode you will see all the vertices,edges and faces. When these vertices,edges and faces are not selected they would appear in black colour. Hit "A" key to select all. Now you will see all the vertices,edges and faces in yellow colour.
You can toggle "A" key to select/deselect all objects in the 3D window.

In edit mode we can work with vertices, edges and faces in a detailed manner to design  any desired shape. A number of tools are available to work in edit mode.

Look at the image below which shows the horizontal panel in edit mode. To the right of the button marked "Global" you will see four square buttons. The first one has a point(vertex) in orange colour, clicking on this enables vertex-select mode. The second button has a vertical line(edge) in orange colour,clicking on which will enable edge select mode, similarly the third button  is used to enable face select mode. The fourth button shows four vertices and edges in the foreground and four vertices  in the background. This button,when clicked on, enables selection of vertices in both foreground and background.

Another way to select  a particular set of vertices and edges is to use the Box or Circle mode, which is activated by pressing "B" or "C" key. This method  is explained earlier under the sub-head "SELECTING OBJECTS".

Once one or more vertex/edge are selected we can delete them,move(translate) them or extrude them or rotate them to create a modified mesh.

After we finish our work in edit mode the modified mesh can be seen as an object in the  object mode(Press Tab key).

TOOL PANEL

Both in object mode and edit mode the Tool panel can be activated by pressing "T" key with the cursor within the 3D window. The Tool panel will be positioned along the left side of the 3D window. Different operations like translate, rotate, extrude and delete can be applied to the object selected in either mode. Side tab with label "Tools", "Create", "Relations, "Animation" are also shown.You may explore using these tools one by one.

NOTE: In Blender, it may be noted that there is always more than one way to do any operation like adding an object,editing, translating,rotating or scaling it.