3D Computer Graphics Using Blender 2.80 - Modelling Methods, Principles & Practice

          Blender Tutorials: V-Roller Guide - part 4

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Part 4 Laying Out The Component Drawings

Most of the techniques necessary to layout an orthographic drawing were covered in Part 11 of the 608 Bearing Tutorial so rather than just repeating what's in that section this will be just a brief description of the layout process.

Initially though I thought it would be good to mention the two standard methods of laying out a drawing. 1st Angle Projection and 3rd Angle Projection. To see how the views are represented on paper it's easier to fold the paper into a cube around the component and project the view onto the cube. When the cube is unfolded it gives the correct layout.

1st Angle Projection 3rd Angle Projection
1st Angle Projection 3rd Angle Projection
In First Angle projection the view is projected through the component, so the front view is projected onto the back wall and the top view is projected onto the base.
In 3rd Angle projection the side facing the cube is projected onto the cube, so the top view is on the top of the box and the front view is on the front of the box.

1st Angle Plan 3rd Angle Plan

When the 1st Angle view is folded out the front view is at the back of the top view and the side view is on the opposite side of the front view. This type of layout often causes confusion with people who aren't completely familiar with orthographic layouts.
In 3rd angle projection the views are positioned on the same side of the view next to them, so the top view is on top of the front view and the side view is on the side of the front view that it represents. This is a much easier layout to understand and my preferred choice.

Hopefully that,s enough for you to appreciate the formal aspects of orthographic layouts, Its a subject where you can go into ever increasing detail and this is just a brief primer to get you started. If you want to learn more about layouts there is a lot of detail on www.technologystudent.com, it's worth a visit as it contains a lot of in depth advice.

I think that's enough on layouts so let's get back to Blender. In part 10 we created a page Layout for an A4 Portrait Page. We can start by importing this and then rotating the border to form an A4 Landscape layout. Start a new Blender project. If you already have Blender open save your work Ctrl-W then press Ctrl-X to open a new file. Delete the Cube Object that opens with each new project X, as we don't need it.

Append all the A4p objects from the PageTemplate.blend file created in the 608-Bearing tutorial. Shift-F1 to open the File Browser window in Append mode and from the "PageTemplate.blend" file LMB click Object then RMB select all the A4p objects. Click on Load Library to bring them into the new file. They will be placed on Layer one, as this was the layer they were created on. Go into front view to see the layout NumPad 1.

In the outliner select the A4pBorder object then in the Link and Materials panel change its name from A4p (portrait) to A4L (Landscape). Repeat this for all the other A4p Objects.

It's now time to rotate the border. The only problem is that the Title box is part of the Border mesh so we first need to separate the Title Box from the Border. Either in the outliner or 3D view select the A4LBorder Object and Tab into Edit Mode. Select All vertices, it's easier to deselect the vertices of the title box than select the vertices of the Border.

To de-select the vertices of the title box press B for box select, but this time drag a selection box over the vertices you need to de-select using the RMB. The vertices will no longer be selected. On the 3D View Header press select>>Inverse, this will invert the selection so the title box is now selected and the Border isn't. (You could have just de-selected all then box selected the Title Box, but I wanted to show the Box Deselect feature!) De-Select Title Box

With the Title Box vertices selected press P (part) to separate them from the current mesh and choose "Selection" from the pop-up menu.

Tab back into Object Mode and select A4LBoundary, Tab back into Edit Mode and select RMB the bottom Right Hand vertex snap the Cursor onto this Shift-S Cursor>Selection.

Tab into Object Mode and RMB select the A4LBorder Object and Shift-RMB select the A4LBoundary Object. In the 3D View Header set the Pivot point to 3D Cursor, then Rotate the Border and Boundary 90 degrees.
Border Rotate

The Border is now disjointed from the Title Box so Grab the Border and move it on the X-axis until the bottom Right Hand corner sits around the Title Box.

The final thing to do is amend the Camera and output Format settings detailed in A4LText.007 so Size X becomes 3300 and Size Y becomes 2400.

You now have an A4 Landscape page template that can be appended back into the PageTemplate.blend file.
A4 Landscape Page Template

Append the V-Roller Object from V-Roller.blend onto the scene and position it within the Border. (If it doesn't appear on the view after appending check the Eye icon in the outliner is open or it's layer is active) Copy this Shift-D and move it on the X-axis to the right of the original. Rotate the copied V-Roller on the Z-axis 90 degrees. Copy the rotated V-Roller and position this to the right of the original. We will use the second copy to form a sectioned view.

Append the V-RollerAxle from the same file and position this within the border. Copy this on the Z-axis and position it above the original. (3rd Angle projection Top view sits above Front View)

Save the file as V-RollerLayout.blend
Append Models

Material Settings We now need to change the material for all the components. Select the 1st V-Roller and In the Links and Pipeline tab of the Material Buttons press the X to remove its material, then click Add New to add a new material.

In the Materials tab set the colour to white and click Shadeless so it renders as a pure white colour.
World Settings
In the World Settings change the Background to white.
With the material set on the first V-Roller Shift-RMB select all the other components, then Shift-RMB select the 1st V-Roller to make it the active object. Press Ctrl-L (Make Links) and select Materials from the popup menu. This will copy the material from the active object onto all the other selected objects.

In the Output tab of the Scene Buttons click Edge to allow the Edge filter to draw an outline around the components and then click on Edge Settings and set Eint (Edge Intensity) to 1 to give lines only on the most prominent edges.

In the Format tab change size X to 3300 and Sixe Y to 2400. Select the camera, go into camera view NumPad 0 and align the camera with the Boundary Object. Set the Camera to Orthographic in the scene buttons Camera tab
Edge Settings

Because we are working with such a large output size you can select areas of the camera view to do a test render. In the camera view press Shift-B and drag a selection box over the area you would like to test. The render will then be confined to the area of the selection.

To come out of Border render de-select Border in the Render tab.
Border Render

In side view NumPad 3 cut the right hand V-Roller in half by deleting all the vertices forward of the centreline. This is easier carried out in local view NumPad /.

Alt-Shift-RMB select the vertices on the two open ends and copy Shift-D them forward of the 1/2 V-Roller on the Y-axis. Shift-F fill these faces, beautify the fill Alt-F and convert to Quads Alt-J. The faces have been separated from the V-Roller to allow the edge filter to detect the edges cleanly.

With the vertices of the disconnected faces still selected we need to add an image texture with a hatch pattern. If you haven't already got one available use one of the textures from the 608-Bearing tutorial Part 11.

In the Link and Materials tab of the Editing Buttons click New to add a second material to the mesh and then press Assign to assign the second material to the selected vertices.
Section View

Add New Material In the Shading Buttons, Texture sub context add a new image texture and load your hatch pattern.

If you need more detail of how to do this go back to the 608-Bearing tutorial, Part 11 describes the process in detail.
Hatch Because Image textures are stretched to fit the object's bounding box size the hatch will have been skewed vertically so increase Y repeat to 2 or 3 in the Map Image tab of the texture buttons. This will repeat the texture 2 or 3 times in the Y-axis.

If you do a test render you should end up with something like the image opposite.

Radial Dimensions
To construct a diameter dimension select a vertex either side of the horizontal centreline and add an edge F. Click on Edge Length in the Mesh Tools 1 tab of the Editing Context buttons. We can use this figure for the dimension text.

Separate this edge from the V-Roller P, choose "Selected" from the popup menu. Tab into Object Mode and select the new edge, which will be used to form the dimension line. Go into Local view NumPad / for dimension line, then Tab into Edit Mode (Note I have removed the material to make the images clearer for this tutorial).

Select both vertices and Extrude them Z 0.1. Select the bottom two vertices and Extrude these Z -0.1 This adds thickness to the dimension line.

Select All and cut K through the horizontal edges choosing Knife (Multicut) from the popup menu and accepting the default 2 cut's.

Select the six new vertices that have been cut and Scale them along the horizontal edges X until they are around 4mm from the ends of the dimension line. Select the two vertices A & B and Extrude them in the Z axis 1mm Repeat this on the other three edges. You should end up with a dimension line that has a box on either end. Dimension Arrow

Select the five left hand vertices and with the Pivot Point set to Median Point Scale the vertices to 0 then Remove Doubles w. You will end up with an arrow shaped end.

Repeat this on the other end of the dimension line.

The next requirement is to add a leader line for the dimension text. Select the three vertices in the yellow box opposite.

Toggle back into Global View NumPad / and extrude these vertices on the X-axis out past the edge of the component.

Add the Black shadeless material from the border to the dimension line.

Tab into Object Mode and in side view NumPad 3 move the  dimension line in front of the V-Roller. With the dimension line selected snap the cursor Shift-S to its object centre Cursor>Selection.
Leader Line

Insert a Text object and in the Editing buttons Font tab, increase its size to suit the page scale (4 on my layout)

Backspace through "Text" to remove it, then add the dimension size using the number keys on the main keyboard (not the NumPad keys)

Tab into Object Mode and move G the text over the leader line.

Finally add the Black material to the text object.

With the cursor snapped to the Object centre copy the the dimension line and text, then rotate the copy from the horizontal.

The original dimension line can now be modified by moving the arrows on the X-axis to a new diameter.
Dimension Text

This technique can also be used for radius dimensions by cutting the dimension line on the centre-point and deleting all the vertices to one side of the cut.

If you haven't been doing so it's worth frequently saving your work. Press Ctrl-W and save the file.

Linear dimensions

Linear dimensions using the Blender Caliper script were covered in detail in the 608-Bearing tutorial Part 11 along with scaled views. If you can't remember how to add the dimensions please revisit Part 11
Choose Verts

As a quick refresher, in Edit Mode select the two vertices where you want the dimension measurement to be taken from. 

Copy the vertices and move them away from the model (constrained to an axis). This gives a break between the extension line and the model. Extrude these vertices to the point where you want the dimension line, then extrude again past this point.

To thicken each edge so it will show on the render, select the three vertices of one edge and extrude it away from the other edge 0.2mm. Do the same with the other edge.
Copy & Extrude

Thicken & Add Dimension To add the dimension select the two vertices on the inner edge of the extension lines. Open Blender Caliper, adjust the measurement settings for the dimension line and press measure. (You may need to play with the settings to get a suitable font size and dimension line scale).

Select the vertices of the extension lines and separate them from the models mesh P. Go into Object Mode and join the extension lines to the dimension line created by Blender Caliper by selecting both objects and pressing Ctrl-J.
As you progress through your layout join all the dimension and extension lines into one object. It helps to change the colour of the dimensions to help differentiate them from the model.

The models are going to be rendered using the edge settings so need to be rendered separately to the drawing border and dimensions. Select all the models and move them onto layer 2
Layer 2 Move then click the second layer box in the popup.
In the Render Layer tab of the scene buttons select layer 2 to limit the render to this layer. In the Output tab make sure Edge is still selected.

In the Format tab select PNG as the file format and check the RGBA button. Render the line drawings of the components. When you save the render it will save the component layout onto a transparent background. Save F3 the drawing as V-RollerLayout1.png
Render Layer

Node Editor To combine this drawing with the border and dimensions, we can use the Node Editor. The Node editor is a complex image editor and needs a book of its own to describe its full capabilities. I will just touch on what's needed to combine the two layers.

In the render Layers tab select layer 1. In the Output tab deselect Edge to turn off the edge filter. Render the layer and close the render window.

In the 3D View click the window type button and choose Node Editor. On the Node Editor Header click on the face icon to select composite nodes, then click Use Nodes. A Render Layer Node and Composite node will appear in the view joined with a curved line.

The nodes will have a thumbnail view of the Border and Dimensions. We now need to add an input node so we can load the image with the line drawings.
Node Editor

Node Menu

Press the SpaceBar to open the node menu choose Add>Input>Image, a new node will appear in the View. You can move the nodes around by LMB dragging the Header at the top of the node. Position the Input Node below the Render Layer Node.

Press Load New and load the drawing V-RollerLayout1.png. The thumbnail of the image will appear in the node. Nodes are arranged with inputs on the left-hand side and outputs on the right-hand side.

We now need to add a node that can combine both the Render Layer and Image nodes together. To do this press the SpaceBar and choose Add>Color>AlphaOver. The AlphaOver node will be placed in the view.
Alpha Over
Input Node

Node Layout
We need to re-wire the nodes to give us the correct output.

LMB click and drag the cursor across the link between the Render Layer Node and the Composite Node. This will cut the connection.

LMB click and hold on the yellow output socket on the Render Layer node and drag the mouse to the bottom yellow input socket on the Alpha Over node. A new connection will be made.

In the same way connect the output of the image node to the top input of the Alpha Over node. Then connect the Output socket of the Alpha Over node to the input socket of the Composite node. The connections are now complete.

Before rendering the layout you must tell Blender to use the composite output. In the Scene buttons Anim tab click Do Composite, then render the layout.

If all has gone well you will get a composite layout with a dimensioned line drawing of the components. In the Scene buttons Format tab Click RGB as we no longer need alpha in the image and Save the Layout drawing F3. Save your file Ctrl-W.

The final thing necessary to print the drawing to scale is to adjust the pixels per inch to 300 in an image-editing program such as Gimp or PhotoShop.

V-Roller Layout

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