AutoCAD solid modelling - 2

This tutorial has been prepared for students studying:

ARCH7221 Computer Modelling and Rendering, and
ARCH5222 Computer Applications 1,

at the School of Architecture, University of New South Wales, Australia.

Introduction
	This second tutorial will introduce the two remaining "Solids" primitives in AutoCAD R13. Then you'll see how to use Constructive Solid Geometry (CSG) to join and cut solids! As with the first tutorial, this one will be short! Start AutoCAD (select Start - Programs - CAD Applications - AutoCAD R13). Before proceeding, split the screen into two vertical viewports (select: View - Tiled Viewports - 2 Viewports, and then press 'Enter' to accept a vertical split line).
Wedge
	Select the 'wedge' icon from the Solids toolbar. Note that there is a small arrow in the bottom right of the icon, you'll remember from the first tutorial that this indicates that there are a number of ways to execute this command. The default (shown on the icon) should have a dot in the centre of the wedge, indicating that the centre point (rather then a corner point) will be selected first. AutoCAD should prompt for the "Center of wedge", pick a position near the middle of the drawing area; the next prompt is for the "Corner of wedge", pick a position on the screen up and to the right of the centre, finally enter a height (by drawing a distance or by typing a value).
	If you haven't already made one of the viewports a 3D view then click on the right view and make it a 3D view (View - 3D Viewport - Tripod, and then view from the 'north east'). You may need to zoom out to increase the space around the object (select the magnifying glass icon with the minus "-").
To change the UCS, type: ucs [enter] and then z [enter] and the angle [enter].	Note that the wedge is created parallel to the crosshair axis, to create a wedge (or other shape) at some other angle, rotate the crosshair or create the shape and then rotate the shape! Draw a couple of wedges (make some intersect others)!
Torus
	Select the torus (donut) icon, enter the "Center of torus"; then enter a second point to provide the "Radius of torus" (note there's an option to enter the diameter instead); then enter a distance (number or two positions) for the radius of the tube. Create a few more tori. This is the last of AutoCAD's Solid Modelling primitives. Now we'll cover some of the commands used to modify those primitives.
Constructive Solid Geometry (CSG)
	AutoCAD has three commands for CSG: union, subtract and intersect. If you can remember the mathematics that you studied in school, these terms may be familiar to you from "Sets". The icons for the CSG commands are "hidden" in the Modify Toolbar!
Union
	As the name suggests, union joins objects together. In joining the objects, any surfaces that are internal to the result are discarded; this is significant, because if you cut a section through a unioned object, you don't want to see all the bits that made up the original parts. If none of your objects intersect at present, create some new objects that do intersect other objects. You can do this by re-issuing the wedge or torus command; or you could use copy or move! Select the union icon (or type "union"), pick two objects and press "Enter". You may notice in the 3D viewport that the objects look slightly different.
Subtract
	As I'm sure you can guess, subtract uses one solid to cut away part of another solid. Start the Subtract command, and then select the object(s) that you want to cut into, press "Enter" when you've picked the object(s); then select the object(s) that will do the cutting, and press "Enter". This command should cause a more significant change to the objects involved, the 'cutting' objects will disappear and the first objects will (hopefully) have holes in them!
Intersect
	The Intersect command operates similarly to the union command. Two (or more) objects are selected and then after the selection process the command executes. The result is that the parts of the objects selected that are common to all the objects are left!
These two views above show two wedges that have been copied 3 times and then unioned, subtracted and intersected.
Render
If you want spheres and cylinders to appear more round, then type: facetres 2 [enter].	Select: AutoVis - AutoVis Toolbar. Drag this toolbar out of the way if you wish. Have a look at the icons and run your mouse along them (slowly) to get the bubble text. Click on the first icon (Render). Set the "Rendering Type" to AutoCAD Render; make sure none of the options under "Rendering Options" are checked (have "X"s), then click Render. Once that has completed (it should only take a moment); click on the Render icon again, this time click the Smooth Shading option and the Render button, you should note that any objects with curves are drawn without faceting. Click on Render again and select AutoVision as the "Rendering Type" (click the Render button). This time you should see some highlights starting to appear, and the image should be "softer"!
Materials
Most of the materials are based on small images. These images lie in the xy-axis, so if you want to have the texture on a vertial surface, select the mapping icon (or type: setuv), select 'adjust coordinates' and change the axis.	During this section we'll apply some predefined materials to the objects created. Select the Materials icon (or type: rmat [enter]). Select the Materials Library... button; this should display the "Materials Library" dialog(!), select a number of materials from the list on the right, for example: aqua glaze, beige pattern, blue glass, blue plastic 50, and checker opa/shin; then click on Import and OK (to dismiss the dialog box), select one of the materials from the listing in the Materials dialog, click on Attach and then select an object. Repeat this process (using different materials) for each of the objects in the drawing. Select the Render icon, click on Apply Materials and Render. The result will probably be a mess(!) but I'm sure you get the idea! *Investigate....!* Remember to save your drawing and exit AutoCAD, before you log-out.


Last Update : 13 October 2000 Major Revision : 29 October 1997 SEARCH . FBE SITEMAP		Disclaimer . Webmasters Page Contact : Stephen Peter Email : S.Peter@unsw.edu.au