The Complete Guide to Blender Graphics
Combining Features

Delete the default cube in the 3D window. Go into “Top Orthographic” view and add a “Torus” object. On entering the “Torus” the “Add Torus Properties” panel displays in the “Tool Shelf” at the left hand side of the screen . Press the “Smooth” button in the “Object Tools” panel.


In “Edit” mode stretch the torus into the shape of the link by selecting one half of the vertices and translating. If you reduce the “Major Segments” from 48 to 46 there will be no vertices on the centre line of the torus which simplifies vertex selection. The detail of a weld joint in the link may be created by loop cutting one of the stretched sides of of the link then translating and scaling the added vertices.


Apply Material to the Link


Note: The single link created will be duplicated to form a chain. Texture will be applied to give the surface of the link realism. Before texture can be applied a material must first be added. Since we will want the whole chain to have the same surface texture we have to apply the material and texture before duplicating the link object. When duplicating the link objects the material and texture properties are also duplicated.

If you inadvertently applied a material with “Blender Render” active, then changed to “Cycles Render” you will have to click on the “Use Nodes” button in the “Materials” buttons to activate the node system.


In either case, in the “Material” buttons, “Surface” tab you will observe that the “Surface” type is by default “Diffuse BSDF”. You may change this to one of the other “Shader” types by clicking where you see “Diffuse BSDF”. Try “Anisotropic BSDF” which is similar to “Glossy” but darker around the edges.

Apply a Texture to the Link


At this stage a texture will be applied to the surface using “Displacement”. This provides surface characteristics not color. An “Image Texture” will be used, which is to say that the variations in color through the spectrum from white to black from the image are mapped to the surface forming surface irregularity.


In the “Properties” window, “Texture” buttons click on “New”. In the “Image” tab click “Open” to display the “File Browser” window. Navigate in your system and select an image. The image will display in the “Texture” buttons, “Preview” tab panel but does not have any affect on the chain link object in the 3D window.

To affect the surface of the object, the object's surface must be unwrapped.


Unwrap the Chain Link


Change the default Blender screen arrangement to the “Compositing Screen Arrangement”.


Note: The “Compositing Screen Arrangement” opens with five windows displayed,  “Node Editor”, “Properties”, “UV Image editor”, “3D Window” and the “Timeline” (Way down in the lower right hand corner). Although this provides a convenient window arrangement it should be noted that individual window may be divided and one division changed to whatever window type is appropriate. In this way a user has full control over the screen arrangement.



In the “UV Image Editor” window click on the “Browse Image to be linked” button in the header and select the image that was previously loaded. You may need to zoom out to see the whole image in the window.

In the 3D window Tab into “Edit” mode and press the A key twice to make sure all the vertices are selected on the link. Place the 3D window in “Top Orthographic” view. With the mouse cursor in the 3D window press the U key to display the “UV Mapping” selection menu and select  “Project From View (Bounds).

Node Editor Window


In the “Node Editor” window header, click on the “Shader” node button and check “Use Nodes”. Make sure the “Object” button is active.

The “Node Editor” window will display a “Diffuse BSDF” node connected to a “Material Output” node. The “Diffuse BSDF” node exhibits the default grey diffuse material color of the selected object (the chain link) in the 3D window. The BSDF socket is connected to the Surface socket of the “Material Output” node hence the grey color of the chain link in the 3d window.


To introduce our image as a “Texture” click on “Add”-”Texture”-”Image Texture” in the “Node Editor” window header. Arrange and connect the “Image Texture” node as shown. Click on the “Browse Image to be linked” button in the node and select the loaded image.

Connect the “Color” socket of the “Image texture” node to the “Displacement” socket of the “Material Output” node. You will see the image on the surface of the chain link in the 3D window (in “Rendered Viewport Shading” mode). The color data from the image displays as shades of grey on the surface of the chain link. Remember we are using the image to provide surface texture not color.




To control the strength of the texture add a “Multiply” node. Click “Add”-”Converter”-”Math” to introduce an “Add” node then change the node to “Multiply”. With the new node connected as shown the strength of the texture may be adjusted by changing the “Value” slider properties. At this time set the “Value to 0.00, that is, no texture.


Having applied material and texture to the chain link object it may duplicated to form a chain.


Chain Link Duplication


Change the screen arrangement back to the default screen. Remember we are in “Top Orthographic” view.


In “Object” mode duplicate the link. Press Shift + D (Duplicates the link and places the duplication in “Grab” mode for translation). Press the X key to confine the translation to the X axis (To combine the commands press Shift + D + X). Translate the duplication as shown (Drag the mouse - See Diagram). Rotate the duplication on the X axis, press R + X + 90. If you determine the exact amount of translation required you can enter the value (Shift + D + X + 2.5 + Enter) Note: The 2.5 translation value is determined by the elongation of the chain link.


Box select both links then duplicate the selection – Shift + D + X + translation value (5.0), press “Enter”. Hold “Shift” and press the R key to repeat the last action, duplicating and translating the two links to form a chain.


With the chain created it is time to set up the animation and to do this we will use “Rigid Body Physics”.


As with many procedures in Blender there are more ways than one to achieve the same result. The following will demonstrate two ways to apply “Rigid Body Physics”.




Apply Physics in the Properties Window


Select a single chain link in the 3D window. Remember at this stage each link is a separate object.


In the “Properties” window, “Physics” buttons click on “Rigid Body”. The “Rigid Body” tab displays showing physics Type: Active and “Dynamic” is checked. In the “Rigid Body Collisions” tab change “Shape: Convex Hull” to “Shape: Mesh”. Changing this is changing the shape of the “Collision Bounds” limits for the object. In simple terms the “Convex Hull” bounding shape is similar to stretching a piece of plastic wrap over the object. Since we are working with an object (Torus) this would cover the hole in the centre. The “Mesh” shape wraps the plastic similar to wrapping an auto tyre leaving the hole exposed. The “Convex Hull” and “Mesh” options are difficult to demonstrate since they both wrap to the mesh surface of the object. The other options can be visualised if you change the 3D window to “Wireframe Viewport Shading” mode.





For the time being, apart from changing the “Rigid Body Collisions: Shape, all other values remain as default. Remember this has applied the physics properties to the single chain link selected. You see this since the selected link has a green outline in the 3D window in “Solid Viewport Shading” mode. Clicking on any other link will show an orange outline.


Applying “Rigid Body” physics to an object gives it properties which allows it to interact with other objects in the scene but in order to do so the other objects have to have the same physics applied. It follows that each chain link requires “Rigid Body” physics. To achieve this have the single link with the physics applied selected. Box select all the links including the link with the physics already applied. In the “Tools” panel at the left hand side of the screen, “Physics” tab under “Object Tools” click on “Copy from Active”. This applies the physics to each of the selected links.


Apply Physics in the Tool Panel


Select the chain (All the links). In the “Tool” panel at the left hand side of the screen, in the “Physics” tab under “Rigid Body Tools”-”Add/Remove, click on “Add Active”. In the same panel under “Object Tools” click “Change Shape” and select “Mesh”. This procedure applies the same physics set-up as described in the previous demonstration.


Note: The chain links remain separate individual objects. If you wish to remove the physics from one or all of the links, select then in the “Rigid Body Tools” click on “Remove”.

Running a Simulation


With “Rigid Body” physics applied you may run a simulation of the chain as it would react in the real world by pressing the “Play” button in the “Timeline” window. With the 3D window in “Front Orthographic” view you will see the whole chain descend under the influence of gravity. The gravitational force is set in the “Properties” window, “Scene” buttons, “Gravity” tab. The Z: -9.81 value represents Earth's gravity in the real world.


In  running the simulation you will find that the action looks like a slow motion replay. This is in part due to the scale being employed in the viewport window. The scale of the chain link created from the default “Torus” object was merely made to look reasonable in the 3D window. The default “Torus” is 2.5 Blender units in diameter. If you change the units of measurements in the “Scene” buttons to Metric you will see that this is 2.5 Meters which is a pretty darned big chain link. The motion in the simulation is exactly what you would expect in the real world with a chain constructed from links of that size. The speed of the simulation may be varied in the “Properties” window, “Scene” buttons, “Rigid Body World” tab but be aware that a dramatic increase will result in a jerky playback. Also scaling the chain way down may also produce unwanted results. For the time being leave everything as default.  


Note: Each chain link is “Active” with “Dynamic” checked as seen in the “Properties” window, “Physics” buttons, “Rigid Body” tab.


To make the simulation more interesting fix one end of the chain in position. To do this select a link at one end of the chain and simply uncheck “Dynamic”. The link remains active in the simulation but is fixed in position in the scene. Running the simulation again will show the chain swing downwards and back and forth under the influence of gravity.


Adding Obstacles


Objects with “Rigid Body” physics applied interact with other “Rigid Body” objects.


Place a “Cylinder” object in the scene as shown in the diagram. Apply “Rigid Body” physics to the cylinder and make it Type: Passive. Change the “Rigid Body Collision”, “Shape” to “Mesh”. This means it will react with other objects but will remain stationary in the scene. Playing the simulation shows the chain swing down and wrap itself over the cylinder.


Also place a “Plane” object in the scene and position it such that the end of the chain comes to rest on the plane.


Add material and texture to the cylinder and the plane.


For “Material”, select each object separately and follow the procedure previously described for the chain link. You may leave the material as the default grey color since “Texture” will be applied to enhance the surface appearance.


For “Texture”, with material already applied, select either object and  in the “Properties” window, “Material” buttons, “Surface” tab, click on the button at the end of the “Color” picker bar. In the selection menu that displays, in the “Texture” category, select “Image Texture”. The “Surface” tab expands to show the “Open” button. Click the button, navigate to an image and select it.


During this process the “Node Editor” window will have been updating and at this stage will have an “Image Texture” node connected to a “Diffuse BSDF” node, connected in turn to an “Material Output” node. The file name of the image you have selected for your texture is shown in the “Image texture” node. You will be disappointed to find that your texture image is not showing on the surface of the selected object even when the 3D window is in “Rendered” viewport shading mode.


Remember for the texture to display the surface of the object has to be unwrapped. Go back and follow the unwrapping procedure that was used for the chain link.


Recap


At this point we should recap and think about what we have up to this point. We have a chain constructed from links and each link has a material applied to its surface. Each link also has a displacement texture applied to its “Anisotropic BSDF” surface. Obstacles have been placed in the scene which interact with the chain when a simulation is played. When the simulation is paused the frame of the animation may be saved as a rendered image. We have therefore achieved our objective but the final objective of any scene or animation is to produce an image or a movie or to form part of a game. The view in the 3D window in “Rendered” viewport shading mode is most likely far from your expectations. There are other factors that come into play. Lighting and the positioning of the camera are two very important consideration. The default point lamp in the default default scene will not cut the mustard (be up to standard). What you see in “Camera” view may not be what you want in your image or in your animation.


Camera Position


It may seem to be stating the obvious but the direction in which the camera is pointing will determine what the final result in an image or video will be. How many times have you seen something in a scene from an old movie that should not have been there. Positioning the camera for that reason applies today although it easier to delete unwanted shots these days.


In the diagram the camera is positioned to show the end of the chain hanging over the cylinder and resting on the plane. Note that the scene background is purposely partially obscured by the cylinder and plane. The reason for this will be made apparent later.


Lighting


There are many tutorials on lighting and once again the options are limitless. For our simple demonstration place two additional lamps in the scene and set their properties as shown in the diagram . This will brighten up the result.



Placing lamps in a scene go part of the way towards achieving an effect. If you think about taking a photo or doing a movie shoot, sure you can use lamps, but even so the environment in which you are working will play an important part in what you achieve.


Environment


To further enhance your image you can add an “Environment Background Texture”. This supplies environmental lighting which will provide reflection from glossy surfaces. Remember we suggested the “Anisotropic” shader for the chain link surface. This gives a glossy reflective surface.


In the “Properties” window, “World” buttons, click on “Use Nodes”. Click the button at the end of the color picker bar and select “Environment Texture” from the menu. The rendered viewport will turn bright pink. Click the “Open” button and navigate to an image on your computer. In “Rendered” viewport shading mode the 3D window will show the image as a background to the scene.


Note: We previously positioned the camera such that the scene background was out of camera view but the environmental lighting is reflected in the glossy surface of the chain links.



Camera Positioning – Lock Camera to View


To aid in positioning, the camera may be “Locked to View”, where the view may be zoomed, panned and rotated. To do this, in the 3D window, in “Camera View”, with the “Camera” selected, press the N key to display the “Properties” panel with properties pertaining to the “Camera”. In the “View” tab check “Lock Camera to View”. Close the “Properties” panel (Press N key). The scene may now be orientated to what the camera sees. Remember, what the camera sees, is what is rendered to an image.



Rendering


Rendering is the process of turning the “Camera” view in the 3D window into a digital image or frame in an animation sequence. We have the “Cycles Render” option set in the “info” window header and with the 3D window in “Rendered Viewport Shading” mode we can see a preview of the render.


To render an image simply press the F12 button on the keyboard or press “Render” in the “Properties” window,”render” buttons, “Render” tab. Remember the “Samples” value in the “Sampling” tab. Increasing the “Samples” value for “Render” will improve the output. Try something like 500. The downside of this is the time it takes to render the image but if you have created a masterpiece you will want the best result possible.


When the render is complete press the F3 button on your keyboard to save the image to file.


Home Book Content Supplements The Author

The Complete Guide to Blender Graphics introduces the components of the Blender program by referencing to the Graphical User Interface. Having studied the book the user may combine the different tools to create images or animations. The combinations are limitless, therefore it is impossible to include tutorials describing every creation possible.


As an introduction to combining or linking Blender features the following is offered.


In this example a model of a chain link will be created and extended into a chain. One end of the chain will be fixed in position, then the chain will be animated to swing down under the force of gravity. The chain will interact with other objects in the scene. The animation will be paused and an image will be created.


“Cycles Render” will be used in conjunction with the Blender “Node” system.


In the “Info” window header change “Blender Render” to “Cycles Render”.  If appropriate (if it speeds up the rendering process) activate GPU rendering in the “User Preferences” window.


The 3D window has several “Viewport Shading” options. When modelling “Solid Viewport Shading” is best used but to see the application of “Material” and “Texture”, “Rendered Viewport Shading” will display the scene in an approximation of the final image.


With “Cycles Render” activated and the 3D window in “Rendered Viewport Shading” mode the window shows a rendered view of the scene and reiterates the render when a property is altered. The quality of the render is governed by the number of passes set for the render process which can be seen as the “Path tracing Samples” value at the top of the 3D window. The default value is 10/10. When a property is altered you will see the reiteration of the render count up to the maximum set value of 10 passes. This value is set in the “Properties” window, “Render” buttons, “Sampling” tab under “Samples”. There are settings here for the final render (Render) and the sample render (Preview) as displayed in the 3D window.