BISECT AN OBJECT

 BISECT AN OBJECT

    The steps listed below will guide you to bisect an object into two pieces.

1. Add an object in Object mode. Now switch to edit mode and select all the vertices of the object.

2. If tool shelf is not visible in the 3D window, press "T" key to make it visible on the left side of your 3D window.

3. In the tool shelf, click on Tools > Mesh>Add>Bisect.

4. Place the cursor near the object and draw a line across the object so as to cut across it.Press Enter key to confirm.

5. In the tool shelf, look below, under the panel named "Bisect" you will find three check boxes, Fill, Clear Inner, Clear outer. Selecting clear inner will delete the lower half of the object, selecting Clear outer, will delete the upper half of the object.  Selecting the Fill check box will cover the cut edge with a face.

6. In edit mode, select all the vertices (eight) of  the upper piece, then press "P" key and click on "Selection" option.

7. Go to object mode, Object>Transform>Origin to Geometry.

8. Deselect both objects, select the upper portion and pull it away.

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.

UNITS IN BLENDER

 UNITS IN BLENDER(Blender Version : 2.79b)

 Units of measure in  Blender are as default set as Blender units. When we open the default screen and then press "N" key to open the properties window where we can see the dimension of the default cube is 2 units along all X,Y and Z axis. These units are defined as Blender units which serves as a general  unit of measure to set dimensions of any object or to compare their dimensions.
 

 Measuring units in Blender can also be set as mm(millimetre), cm(centimetre), m(metre) or as inch, feet, yard etc. To set the units with these units, the procedure is as follows:

 In the Properties window click on the "scene" BUTTON.(the third button from the left). You will see the drop down panel with heading "Units" and the button marked "None" which  would be highlighted with Blue colour. Click on Metric. Now move to 3D window and make sure you have added an object(let us say a Cube). Now hit "N" key to open the panel which would display the location, scale and dimension of the cube. Under Dimension, enter 10cm for x,y, and z dimension. The background  grid would change accordingly and the unit as  cm will be displayed at the top left corner of the 3D window.

 If you select the option "Imperial", then you can set the unit as inches or feet.

BOOLEAN MODIFIER

 BOOLEAN MODIFIER

 Boolean Modifier can be used to do the following three operations on an object- ie, union, intersect or difference.
 

  When we apply  an union operation then the end result is the combined shape of the two objects. Intersection is the the shape of the two objects where they commonly intersect. In case of difference, it the shape of the second object is removed from the first object. As an example if you consider a cube and a cylinder. when you do an union operation it will be the combined shape of the two objects. If you do intersection then it will be length of the cylinder which is intersecting with the cube will be the result. In case of difference the end result will be a cube in which the volume up to which the cylinder intersects with the cube is removed as if a hole is drilled in the cube body.

 To apply the Boolean Modifier, the steps are as follows: In the 3D window, add a Cube scale it 3 time along the X and Y axis. Add a cylinder and scale it 5 times along Z axis only.
To do the union operation, locate the Cube a convenient location, the position the cylinder on the Cube such that about 3 units length of the cylinder is inserted into the Cube.

 Now go to the Properties window and click on the spanner icon to open  the Add Modifier drop down menu. Click on "Add Modifier" . Under Generate heading,click on Boolean, under operation select Union. Select the Cube in the 3D panel, under Object click inside the window where you see an ink dropper icon. Select the cylinder. Then click on the Apply
button. Click on the cylinder to select it and drag it away. You will the Cube and cylinder joined as a single object.

 Follow the same procedure for intersect or difference. Corresponding to this operation the setting under "Operation" should be selected as Intersect or Difference.Then click on Apply. After the operation move the cylinder away to see the end result.

NOTE: When you are positioning the two object in the 3D window, under "View Port shading"  select wire frame. This will give wire frame view of both the objects.This view option is preferable over the solid view option.

 

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.