Chapter 4 Modeling Basics

From ShadeCamp

In this chapter we’ll look at the basic user interface you will use in Shade to model an object.

Contents 1 Using the Create Tool 1.1 Rectangles and Disks 1.2 Spheres 1.3 Closed Lines and Open Lines 2 Creating Line Objects 2.1 Drawing Straight Lines 2.2 Closing Open Lines 2.3 Drawing Curves 2.4 Drawing Lines with both Straight Segments and Curves 3 Modifying Control Points 3.1 Selecting Control Points 3.2 Selecting Multiple Control Points 3.3 Selecting Multiple Control Points at Once 3.4 Deselecting Control Points 3.5 Deselecting All Control Points 3.6 Moving a Control Point 3.7 Adding a Control Point 3.8 Deleting a Control Point 3.9 Creating Tangent Handles 3.10 Unlinking Tangent Handles 3.11 Changing a Tangent Handle’s Length and Angle 3.12 Deleting Tangent Handles 4 Extruding and Revolving 4.1 Extruding a Disk 4.2 Revolving 5 Curved Surfaces

Using the Create Tool

Many of the tools in the Toolbox contain several options. When you click a tool with multiple options a submenu will appear. One of the first tools you’ll want to become familiar with is the Create tool. The Create tool is used to draw all types of basic objects.

Rectangles and Disks

1. Select File > New to open a blank scene.
2. Click on the Create tool, and select Rectangle from the submenu. In the Top view, click and drag diagonally to draw a rectangle.
   
3. Now click once in the Perspective view to shift focus to that view. Select Rendering > Display Mode > Shading. This changes the preview display mode of the Perspective view to give shading to the objects in the scene.
   
4. Notice that a “Closed line” object has been added to the Browser. This is the rectangle you just drew. Once drawn, Shade treats rectangles the same way as other closed-line objects, which is why it’s not simply called “Rectangle.”
   
5. You can repeat the above steps to create a disk, by selecting Disk instead of Rectangle from the Create tool. The distance you drag in the Figure window determines the radius of the disk.

Spheres

1. This time select Sphere from the Create tool.

2. Click and drag in the Top view just like you did for the rectangle and disk. The distance you drag determines the radius of the sphere, centered around the point you clicked.

3. Notice that “Sphere” has been added to the Browser.

Closed Lines and Open Lines

When drawing lines in Shade you will always start with a start point and end with an end point. Simple. The difference between closed and open lines is that the start and end points of closed lines are automatically connected together. Open lines can be line segments, curves, or a series of straight and curved segments with two end points.

Creating Line Objects

Drawing Straight Lines

Here we will open a template file and practice drawing straight line segments.

1. Since we’ll be working in the Top view, select Figure > View Mode > Top View so that the Top view fills the entire Figure window.
2. Select Figure > Template > Load Top View... to open a file Open dialog.
   
3. Navigate to the Documentation/Beginner Tutorials folder inside your Shade installation folder and open “BT_04_Template.bmp.” The template appears in the Top view. To make the template a bit easier to see, turn off the grid by unchecking the Grid checkbox in the Control Bar.
4. Select Open line from the Create tool in the Toolbox. First we’ll draw the line segment from point 1 to point 2. To do this, click at point 1 and then move the cursor to point 2.
5. Click on point 2 and move the cursor to point 3.
6. Click on point 3. Now we could keep going by clicking on different points to create more lines, but here we only want two line segments, so click the Finish button in the Toolbox.

Closing Open Lines

Open lines can be converted to closed lines, and conversely closed lines can be converted to open lines.

1. In the previous section we created an open line. Select this open line now in the Browser (if it’s not already selected). Next open the Object Info window by selecting View > Object Info. The Object Info window displays information about the currently selected object.
   
2. To convert the open line to a closed line, check the Closed box in the Object Info window.
   
3. You’ll see the third side of the triangle drawn in the Figure window, connecting points 1 and 3. Closing an open line will always connect the start (first) point with the end (last) point.
   
4. The name of the object has also changed from “Open line” to “Closed line” in the Browser. You can do the reverse (convert a closed line to an open line) simply by selecting the line object and clearing the Closed checkbox in the Object Info window.

Drawing Curves

1. We’ll continue to use the same template from the previous section. This time let’s trace the middle line.
   
2. Select Open line from the Create tool in the Toolbox.
3. Click at point 1 of the second (middle) line and hold down the mouse button. Drag the cursor to point 1A and release the mouse button.
   
4. Now move the cursor to point 2, click and hold down the mouse button, and drag to point 2A. Release the mouse button at point 2A.
   
5. Click at point 3, drag the cursor to point 3A and release. Finally, click the Finish button in the Toolbox. At this point you may want to practice drawing straight and curved lines, but we’ve covered all the basics you need to know. In the next section we’ll try drawing compound lines that have both straight and curved segments, using the methods you’ve learned.
   

Drawing Lines with both Straight Segments and Curves

Now let’s practice drawing lines that alternate between straight segments and curves.

1. Select Open line from the Create tool in the Toolbox.
   
2. In the bottom template, click once at point 1 and then at point 2. This draws the straight line segment. To draw a curve click at point 2A while holding down Crtl (Win) or Option (Mac). Then release the key.
   
3. Click at point 3 and then drag the cursor to point 3A while holding down the mouse button. Release the mouse button at point 3A.
4. Next click at 3B while holding down Crtl (Win) or Option (Mac). Then release the key. The tangent handle bends at point 3, where you last did a normal click.
   
5. Click at point 4 and drag the cursor to point 4A while holding down the mouse button. Release the mouse button at point 4A.
   
6. Hold down Crtl (Win) or Option (Mac) while clicking at point 4 again and then release the key.
   
7. Click at point 5 once to create the tangent handle. Click at point 5 once more to create the end point. Click the Finish button in the Toolbox to complete the line drawing.
   

Modifying Control Points

Control points and tangent handles can be modified even after an object is created. Before you can modify an existing object you need enter Modify mode. Select the object you wish to modify, and then select Enter Modify Mode from the Modify tool in the Toolbox. In this section let’s use the last line object we drew in the section above, the line with both straight and curved segments.

Selecting Control Points

If you click a control point it will turn red, indicating that it is selected. The colors used in the Figure window can all be customized in the Preferences (Edit > Preferences), but by default, red means “I’m selected.”

Selecting Multiple Control Points

If you want to select more than one control point, hold down Crtl (Win) or Option (Mac) while you click additional control points.

Selecting Multiple Control Points at Once

Control points can also be selected using one of the three selection tools in the Toolbox: the Box, Lasso and Trace selection tools.

The Box selection tool is the default method. Simply click and drag the box around the control points you wish to select. The Lasso selection tool works the same way, but allows you to freehand draw a “lasso” around the desired control points. The Trace selection tool is usually used for selecting polygons rather than control points. For more information on the selection tools, see “Selecting Objects in the Figure Window“ on page 000.

Deselecting Control Points

Simply click on a selected (red) control point while holding down Crtl (Win) or Option (Mac) to deselect it.

Deselecting All Control Points

To deselect all the control points hold down Crtl (Win) or Option (Mac) and click anywhere in the Figure window (anywhere except on a control point).

Moving a Control Point

To adjust the position of a control point, first select it (so it turns red) and then click and drag it to a new location.

Adding a Control Point

To add a new control point to the middle of a line object, hold down the X and Z keys (Win) or Option1 and Option (Mac) and click and drag across the line. A new control point is added to the location you dragged across.

Deleting a Control Point

To delete a control point, hold down the X and Z keys (Win) or Option1 and Option (Mac) and click the control point you wish to remove.

Creating Tangent Handles

Click and drag a control point while holding down Z (Win) or Option (Mac) to create a pair of tangent handles.

Unlinking Tangent Handles

To separate a pair of tangent handles so that each handle moves independently, click and drag the handle you wish to move while holding down Z (Win) or Option (Mac).

Changing a Tangent Handle’s Length and Angle

The tangent handles of a control point can be moved to change the shape of the line or curve. Simply click and drag the end of a tangent handle to move it. You can change its length or its orientation.

Deleting Tangent Handles

Click the end of a tangent handle while holding down X (Win) or Option (Mac) to delete it. The line or curve will change its shape to reflect the fact that there is no longer a tangent handle.

Extruding and Revolving

Revolving and extruding are two methods of creating solid objects from flat shapes in Shade. Extrusions are created by “stretching” a two-dimensional object in a third direction. Revolved objects are made by revolving a flat object about an axis.

Extruding a Disk

1. Before creating an extrusion you’ll need to create a flat object such as a rectangle, disk or line. Here let’s create a disk in the Top view.
   
2. Select Extrude from the Solid tool in the Toolbox. In the Front view--you should be viewing the disk on edge--click and drag downwards, perpendicular to the plane of the disk.
   
3. The disk is extruded in the direction and length you specified, creating a cylindrical shape.
   

Revolving

1. First click on the origin in the Side view to set the cursor to that point along the X axis. The choose Disk from the Create tool and draw a disk in the Front view to one side.
   
2. Select Revolve from the Solid tool. In the Front view, click and drag in a vertical direction along the Y axis (to one side of the disk).
   
3. The disk is revolved about the axis you specified, creating a torus.
   

Curved Surfaces

1. In the Top view let’s create three open lines, with three control points in each one.
   
2. Select Curved Surface from the Part tool to create a curved surface part, or container, for the lines. In the Browser, move each of the lines inside the curved surface part, in order from left to right in the Figure window.
   
3. You now have something that looks like a flat rectangle. It may not look fancy, but curved surface parts such as this often form the building blocks used to create more complex objects in Shade.
   
4. Although we started with three open lines, our curved surface is actually composed of six lines-- three in each direction. Shade lets you edit any of the lines in a single direction at once. To switch to the other (perpendicular) direction, select Switch from the Modify menu. Now you can select and edit the other lines in Modify Mode.
   
   

For more information on curved surfaces, see Chapter 7: Working with Curved Surfaces in the User Guide. |