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From: <sta...@us...> - 2008-06-21 11:00:20
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Revision: 31518
http://brlcad.svn.sourceforge.net/brlcad/?rev=31518&view=rev
Author: starseeker
Date: 2008-06-20 11:13:46 -0700 (Fri, 20 Jun 2008)
Log Message:
-----------
And add the new lesson 2 to the book using xinclude
Modified Paths:
--------------
brlcad/trunk/doc/docbook/book/tutorial_series/VolumeII.xml
Modified: brlcad/trunk/doc/docbook/book/tutorial_series/VolumeII.xml
===================================================================
--- brlcad/trunk/doc/docbook/book/tutorial_series/VolumeII.xml 2008-06-20 18:12:58 UTC (rev 31517)
+++ brlcad/trunk/doc/docbook/book/tutorial_series/VolumeII.xml 2008-06-20 18:13:46 UTC (rev 31518)
@@ -217,676 +217,16 @@
<chapter id="Lesson-2">
<title>Learning the Viewing Options</title>
-
- <para>
- In this lesson, you will:
-
- <itemizedlist mark='bullet'>
- <listitem>
- <para>Create a model radio.</para>
- </listitem>
- <listitem>
- <para>Locate viewing information in the Command Window.</para>
- </listitem>
- <listitem>
- <para>Identify elements of the <application>MGED</application> viewing system.</para>
- </listitem>
- <listitem>
- <para>View your radio from different angles.</para>
- </listitem>
- <listitem>
- <para>Work with Shift Grips.</para>
- </listitem>
- </itemizedlist>
- </para>
-
- <para>
- Models in <application>BRL-CAD</application> are constructed in a single xyz coordinate system, which
- we sometimes refer to as model space. The Graphics Window of <application>MGED</application> displays
- a portion of this space. The xyz coordinate system is used for specifying
- both the geometry and the view of the geometry that is presented in the
- Graphics Window.
- </para>
-
- <para>
- <application>MGED</application> offers a default view and a variety of optional views. You can switch
- back and forth between these views during and after model creation. This
- lesson is designed to help you understand the viewing process and options.
- </para>
-
- <sect1>
- <title>Creating a Radio</title>
-
- <para>
- To gain practice viewing actual geometry, let's build a simple geometric
- object-a "walkie-talkie" radio. Note that the commands we use to do this
- are not discussed here because our current concern is on applying the
- principles of viewing. Later lessons on creating geometry address these
- commands in detail. Begin by launching <application>MGED</application> and creating a new database
- named radio.g. Remember that one way to do this is to type the following
- command in a Terminal Window:
-
- <command>$ mged radio.g</command>
- </para>
-
- <para>
- Type the following in the Command Window, carefully checking each line
- before pressing ENTER. If you make a mistake, use BACKSPACE or the left/
- right arrow keys to make corrections before pressing ENTER (see Appendix B
- for the editing command list).
- </para>
-
- <note>
- <para>
- Be especially careful to note the difference between the numeral one
- [1] and the letter l [l] in ell1 on the third line.
- </para>
- </note>
-
- <literallayout>
- <command>in body.s rpp 0 16 0 32 0 48[ENTER]</command>
-
- <command>in btn.s rec 8 30 36 0 3 0 4 0 0 0 0 2[ENTER]</command>
-
- <command>in btn2.s ell1 8 33 36 4 0 0 2[ENTER]</command>
-
- <command>in spkr.s tor 16 16 16 1 0 0 12 1[ENTER]</command>
-
- <command>in ant.s rcc 2 2 46 0 0 48 1[ENTER]</command>
-
- <command>in knob.s rcc 4 4 40 8 0 0 5[ENTER]</command>
- </literallayout>
-
-
- <note>
- <para>
- Note that in the preceding Command Line expressions, btn is an
- abbreviation for button, ant is an abbreviation for antenna, and spkr
- is an abbreviation for speaker. Also note that the numbers could have
- been separated by single spaces. The extra spaces were inserted
- simply to improve readability. For some usages (e.g., the r and comb
- commands, which are discussed later), the number of spaces has to be
- exact.
- </para>
- </note>
-
- <para>
- An image similar to the following should now appear in the Graphics
- Window.
-
- <figure>
- <title> Default View of a Radio</title>
- <screenshot>
- <graphic fileref="defaultradio.png"/>
- </screenshot>
- </figure>
- </para>
- </sect1>
-
- <sect1>
- <title>Locating Viewing Information in the Command Window</title>
- <para>
- Now take a minute to look at the Command Window. Even if nothing is in the
- window, enclosed in the bottom border is a string of information about the
- Graphics Window. An example string might read:
-
- <literal>cent=(8.000 16.000 24.000) sz=96.000 mm az=35.00 el=25.00 tw=-0.00
- ang=(0.00 0.00 0.00)</literal>
- </para>
- <para>
- As detailed in the following table, this information contains four groups
- of viewing data about the Graphics Window.
-
- <table frame='all'><title>Viewing Data at the Bottom of the Command Window</title>
- <tgroup cols='5' align='center' colsep='1' rowsep='1'>
- <colspec colname='c1'/>
- <colspec colname='c2'/>
- <colspec colname='c3'/>
- <colspec colname='c4'/>
- <colspec colname='c5'/>
- <thead>
- <row>
- <entry>Screen Designation</entry>
- <entry>Viewing Information</entry>
- <entry>Location of Variables</entry>
- <entry>Default Units</entry>
- <entry>Default Values</entry>
- </row>
- </thead>
- <tbody>
- <row>
- <entry>cent=</entry>
- <entry>Center of View</entry>
- <entry>First 3 numbers</entry>
- <entry>Millimeters</entry>
- <entry>0.000 0.000 0.000</entry>
- </row>
- <row>
- <entry>sz=</entry>
- <entry>Size of View</entry>
- <entry>4th number</entry>
- <entry>Millimeters</entry>
- <entry>Dependent upon size selected</entry>
- </row>
- <row>
- <entry>az=</entry>
- <entry morerows='1' valign='middle'>Viewing Angle</entry>
- <entry morerows='1' valign='middle'>5th and 6th numbers</entry>
- <entry morerows='1' valign='middle'>Degrees</entry>
- <entry>35.00</entry>
- </row>
- <row>
- <entry>el=</entry>
- <entry>25.00</entry>
- </row>
- <row>
- <entry>tw=</entry>
- <entry>Twist</entry>
- <entry morerows='1' valign='middle'>7th-10th numbers</entry>
- <entry morerows='1' valign='middle'>Degrees</entry>
- <entry>0.00</entry>
- </row>
- <row>
- <entry>ang=</entry>
- <entry>Angle of View</entry>
- <entry>0.00 0.00 0.00</entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </para>
- </sect1>
-
- <sect1>
- <title>Identifying Elements of the <application>MGED</application> Viewing System</title>
-
- <sect2>
- <title>Center of View</title>
- <para>
- The first set of information tells you the center of what you are viewing.
- You can change the center of where you are looking through both the GUI
- and the Command Window.
- </para>
- <para>
- To change the center of your view of the radio using the GUI, press the
- SHIFT key and any mouse button while dragging the mouse. (This is an
- example of a Shift Grip, which is described later in this chapter.) You
- can also change the center of view by placing the mouse pointer where you
- want the center to be and clicking the middle mouse button.
- </para>
- <para>
- To change the center of view using the Command Window, simply type at the
- prompt the word center followed by three values for x, y, and z (which is
- the 3-D coordinate system mentioned previously). For example:
-
- <command>center 0 15 325.735[Enter]</command>
-
- As you change your view of the geometry, notice that the numbers in the
- brackets after the cent= title will change to reflect the new center of
- the view.
- </para>
- </sect2>
-
- <sect2>
- <title>Size of View</title>
-
- <para>
- The size of the view is the amount of model space that is shown in the
- Graphics Window. For example, consider using a camera with a zoom lens to
- photograph a rose. As shown in the following figures, if you zoom in on
- the rose, it will appear large in relation to your viewing field. If you
- zoom out, it will appear smaller. In actuality, the view size for the rose
- image on the left might represent only 15 mm across while the view size
- for the image on the right might represent 100 mm across. In both cases,
- however, the actual size of the rose is the same.
- </para>
-
- <informaltable>
- <tgroup cols='2'>
- <tbody>
- <row>
- <entry><graphic/></entry>
- <entry><graphic/></entry>
- </row>
- <row>
- <entry>Zoom In to View Details (small size of view)</entry>
- <entry>Zoom Out to View Object
- in Relation to Environment (large size of view)</entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
-
- <para>
- To change the view size of your radio through the GUI, click the right
- mouse button to zoom in and the left mouse button to zoom out. Each time
- you click the left or right mouse button, the view of the design will
- increase or decrease in size by a factor of 2 (i.e., two times larger or
- two times smaller than the previous size).
- </para>
- <para>
- You can also zoom in or out on your design by going to the View menu and
- selecting Zoom In or Zoom Out. A drawback to this method is that you can
- only zoom in or out one time because the drop-down menu closes once you
- make a selection.
- </para>
- <para>
- If you get lost at any point while creating a model, you can use the zap
- (Z) command to clear the geometry from the Graphics Window and then recall
- the shape with the draw command. When drawing in an empty Graphics Window,
- <application>MGED</application> automatically sizes the view to fit what you draw into the window.
- </para>
- <para>
- You can control the view size of your radio more accurately with the
- Command Window. To set the size to 100 (of whichever units you have
- selected), type at the prompt:
-
- <command>size 100[Enter]</command>
- </para>
- <para>
- You can also zoom in or out on a design by typing zoom on the Command
- Line. To make your radio appear 50% smaller, you would type:
-
- <command>zoom 0.5[Enter]</command>
- </para>
- <para>
- To make your radio appear twice as large, you would type:
-
- <command>zoom 2[Enter]</command>
- </para>
-
- <note>
- <para>
- Remember that changing the view size does NOT affect the size of the
- object. You will change the size of an object in Lesson 6.
- </para>
- </note>
- </sect2>
-
- <sect2>
- <title>Angle of View</title>
-
- <para>
- Azimuth, elevation, and twist (all measured in degrees) determine where
- you are in relation to the object you are viewing. Azimuth determines
- where you are around the sides of it (i.e., to the front, left, right,
- behind, or somewhere in between), elevation determines where you are above
- or below it, and twist determines the angle you are rotated about the
- viewing direction.
- </para>
- <para>
- To better understand azimuth, imagine walking around a truck with a camera
- to photograph it. As shown in the following illustrations, you would be at
- 0'0 azimuth if you stood directly in front of the truck to take its
- picture. If you circled around slightly to your right, you would be at
- 35'0 azimuth. If you moved further around until you were looking directly
- at the driver's side (in U.S. trucks), you would be at 90'0 azimuth.
- Standing behind it would put you at 180'0 azimuth. If you were facing the
- passenger's side, you would be at 270'0 azimuth.
- </para>
-
- <note>
- <para>
- The terms azimuth, elevation, and twist are similar to the terms yaw,
- pitch, and roll, respectively, which are common terms in the
- aerospace industry.
- </para>
- </note>
-
-
- <informaltable frame="none">
- <tgroup cols='2'>
- <tbody>
- <row>
- <entry><graphic/></entry>
- <entry><graphic/></entry>
- </row>
- <row>
- <entry>Front (az=0, el=0)</entry>
- <entry>az=35, el=0</entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
-
- <informaltable frame="none">
- <tgroup cols='2'>
- <tbody>
- <row>
- <entry><graphic/></entry>
- <entry><graphic/></entry>
- </row>
- <row>
- <entry>Left (az=90, el=0)</entry>
- <entry>Rear (az=180, el=0)</entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
-
- <informaltable frame="none">
- <tgroup cols='1'>
- <tbody>
- <row>
- <entry><graphic/></entry>
- </row>
- <row>
- <entry>Right (az=270, el=0)</entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
-
- <para>
- Elevation, on the other hand, involves the viewer's position above or
- below an object. In the preceding example, you circled around a truck
- without changing your relative height. You had an elevation of 0'0, which
- means you were level with it. As the following figures illustrate,
- however, imagine stopping at the 35'0 azimuth position and then climbing a
- ladder to photograph the truck from 25'0 elevation. Climbing higher, you
- would be at 60'0 elevation. If you were directly above it with the camera
- facing down, you would be at 90'0 elevation. If you crawled under the
- truck and looked directly up at it, you would be at -90'0 elevation.
- </para>
-
- <informaltable frame="none">
- <tgroup cols='2'>
- <tbody>
- <row>
- <entry><graphic/></entry>
- <entry><graphic/></entry>
- </row>
- <row>
- <entry>az=35, el=0</entry>
- <entry>az=35, el=25</entry>
- </row>
- <row>
- <entry><graphic/></entry>
- <entry><graphic/></entry>
- </row>
- <row>
- <entry>az=35, el=60</entry>
- <entry>az=35, el=90</entry>
- </row>
- <row>
- <entry><graphic/></entry>
- <entry><graphic/></entry>
- </row>
- <row>
- <entry>Top (az=270, el=90)</entry>
- <entry>Bottom (az=270, el=-90)</entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
-
- <para>
- Finally, twist (which is an optional setting in <application>MGED</application>) specifies a rotation
- about the viewing direction. This rotation is applied to the view after
- azimuth and elevation have been designated. So, returning to our truck
- example, imagine standing in front of the vehicle (az=0, el=0) and then
- tilting your camera counterclockwise 14'0. This would give your view a
- 14'0 twist angle, as shown in the following figure (on the left). Note
- again that it is not the truck that is tipped up, but simply your view of
- it. For more information on specifying twist, see the <command>ae</command> command in
- Appendix A.
-
- <informaltable frame="none">
- <tgroup cols='1'>
- <tbody>
- <row>
- <entry><graphic/></entry>
- </row>
- <row>
- <entry>Front (az=0, el=0, tw=14)</entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
- </para>
- </sect2>
- </sect1>
-
- <sect1>
- <title>Summing up on Azimuth and Elevation and the xyz Coordinate System</title>
-
- <para>
- As mentioned at the start of this lesson, <application>MGED</application> operates in a
- three-dimensional coordinate system (determined by the x, y, and z axes).
- Azimuth is measured in the xy plane with the positive x direction
- corresponding to an azimuth of 0'0. Positive azimuth angles are measured
- from the positive x axis toward and past the positive y axis. Negative
- azimuth angles are measured in the other direction.
- </para>
-
- <figure>
- <title>Azimuth, Elevation, and the xyz Coordinate System</title>
- <screenshot>
- <graphic fileref="coordsystem.png"/>
- </screenshot>
- </figure>
-
- <para>
- If the azimuth angle is 0, then elevation is measured in the xz plane with
- +90'0 corresponding to the positive z direction and -90'0 corresponding to
- the negative z direction. However, if azimuth is not 0, these angles are
- in a plane aligned with the azimuth direction.
- </para>
- </sect1>
-
- <sect1>
- <title>Viewing Your Radio from Different Angles</title>
-
- <para>
- Let's now experiment with different views of your radio. <application>MGED</application> has several
- standard default views, which you've already seen in the preceding truck
- example. They include Top (az270, el90); Bottom (az270, el-90); Right
- (az270, el0); Left (az90, el0); Front (az0, el0); Rear (az180, el0); az35,
- el25; and az45, el45.
- </para>
-
- <para>
- Go to the View menu and try viewing your radio from different angles.
- </para>
-
- <informaltable frame="none">
- <tgroup cols='2'>
- <tbody>
- <row>
- <entry><graphic/></entry>
- <entry><graphic/></entry>
- </row>
- <row>
- <entry>Top</entry>
- <entry>az35,el25</entry>
- </row>
- <row>
- <entry><graphic/></entry>
- <entry><graphic/></entry>
- </row>
- <row>
- <entry>Right</entry>
- <entry>Front</entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
-
- <para>
- You can also select any azimuth-elevation combination from the Command
- Line. For example, at the prompt type
-
- <command>ae 128 17[Enter]</command>
-
- As with many of the Command Line options, this method of selecting views
- provides a finer degree of control/precision when you need it.
- </para>
-
- <para>
- <application>MGED</application> can also display multiple views simultaneously. Go to the Modes menu
- and click on Multipane. Four small panes with different views should
- appear in your Graphics Window, as shown in the following illustration.
- </para>
-
-
- <figure>
- <title>Multipane View of the Radio</title>
- <screenshot>
- <graphic fileref="multradioviews.png"/>
- </screenshot>
- </figure>
- </sect1>
-
- <sect1>
- <title>Working with Shift Grips</title>
-
- <para>
- The Shift Grip options of <application>MGED</application> are handy hot-key and mouse button
- combinations that can be used in two different ways. With regard to our
- present discussion on viewing, the Shift Grips can, in effect, "drag" the
- world around in front of the viewer (but without actually changing the
- coordinates of the viewed objects). The same Shift Grips can also be used
- in Edit mode to actually move or alter the geometry of your objects. In
- both cases, the Shift Grips appear to do the same thing, so it is
- important always to know the mode in which you are operating.
- </para>
-
- <para>
- In general, the SHIFT key translates (moves), the CTRL key rotates, and
- the ALT key constrains (or limits) translation or rotation to a particular
- axis (x, y, or z). These axes correspond to the three mouse buttons as
- follows: the left button represents the x axis, the middle button
- represents the y axis, and the right button represents the z axis. In
- addition, the SHIFT and CTRL keys can be used in conjunction with any
- mouse button to scale an object (although the ALT key will not constrain
- this action). The following table lists all of the key bindings and their
- functions.
- </para>
-
- <table frame='all'>
- <title>Shift Grip Keys and Effects</title>
- <tgroup cols='5' align='center' colsep='1' rowsep='1'>
- <colspec colname='c1'/>
- <colspec colname='c2'/>
- <colspec colname='c3'/>
- <colspec colname='c4'/>
- <thead>
- <row>
- <entry>Function</entry>
- <entry>Key Combination</entry>
- <entry>Effect in Normal Viewing</entry>
- <entry>Effect in Edit Mode</entry>
- </row>
- </thead>
- <tbody>
- <row>
- <entry>Translate (Move)</entry>
- <entry>SHIFT + any mouse button + mouse drag</entry>
- <entry>Moves view in any direction</entry>
- <entry>Translates object in any direction</entry>
- </row>
- <row>
- <entry>Rotate</entry>
- <entry>CTRL + any mouse button + mouse drag</entry>
- <entry>Rotates view in any direction</entry>
- <entry>Rotates object in any direction</entry>
- </row>
- <row>
- <entry morerows='2' valign='middle'>Constrain Translation</entry>
- <entry>SHIFT + ALT + left mouse button + mouse drag</entry>
- <entry>Moves view in the x direction</entry>
- <entry>Translates object in the x direction</entry>
- </row>
- <row>
- <entry>SHIFT + ALT + middle mouse button + mouse drag</entry>
- <entry>Moves view in the y direction</entry>
- <entry>Translates object in the y direction</entry>
- </row>
- <row>
- <entry>SHIFT + ALT + right mouse button + mouse drag</entry>
- <entry>Moves view in the z direction</entry>
- <entry>Translates object in the z direction</entry>
- </row>
- <row>
- <entry morerows='2' valign='middle'>Constrain Rotation</entry>
- <entry>CTRL + ALT + left mouse button + mouse drag</entry>
- <entry>Rotates view about the x axis</entry>
- <entry>Rotates object about the x axis</entry>
- </row>
- <row>
- <entry>CTRL + ALT + middle mouse button + mouse drag</entry>
- <entry>Rotates view about the y axis</entry>
- <entry>Rotates object only about the y axis</entry>
- </row>
- <row>
- <entry>CTRL + ALT + right mouse button + mouse drag</entry>
- <entry>Rotates view about the z axis</entry>
- <entry>Rotates object aboutthe z axis</entry>
- </row>
- <row>
- <entry>Scale</entry>
- <entry>SHIFT + CTRL + any mouse button + mouse drag</entry>
- <entry>Scales view larger or smaller</entry>
- <entry>Scales object larger or smaller</entry>
- </row>
- </tbody>
- </tgroup>
- </table>
-
- <caution>
- <para>
- Depending on your window manager or desktop environment settings,
- some key combinations may already be designated to perform other
- tasks (e.g., resizing or moving a window). If so, you may need to
- adjust settings to allow the Shift Grip options to function.
- Furthermore, left-handed users may have switched the behavior of the
- left and right mouse buttons in their system configurations. In such
- instances, the terms left mouse button and right mouse button should
- be switched throughout this document.
- </para>
- </caution>
-
- <para>
- Probably the easiest way to familiarize yourself with the Shift Grip
- options is to try them out on your radio. Using the preceding table as a
- guide, experiment with translating, rotating, constraining translation and
- rotation to particular axes, and sizing your radio view.
- </para>
-
- <note>
- <para>
- Remember, although the Shift Grip options may appear to be
- manipulating objects, unless you are in Edit mode they are only
- manipulating your view of the objects.
- </para>
- </note>
- </sect1>
-
- <sect1>
- <title>Review</title>
-
- <para>
- In this lesson, you:
-
- <itemizedlist mark='bullet'>
- <listitem>
- <para>Created a model radio.</para>
- </listitem>
- <listitem>
- <para>Located viewing information in the Command Window.</para>
- </listitem>
- <listitem>
- <para>Identified elements of the <application>MGED</application> viewing system.</para>
- </listitem>
- <listitem>
- <para>Viewed your radio from different angles.</para>
- </listitem>
- <listitem>
- <para>Worked with Shift Grips.</para>
- </listitem>
- </itemizedlist>
- </para>
- </sect1>
+ <xi:include href="../../lessons/mged/learning_viewing_options.xml" xpointer="overviewlist"/>
+ <xi:include href="../../lessons/mged/learning_viewing_options.xml" xpointer="intropara1"/>
+ <xi:include href="../../lessons/mged/learning_viewing_options.xml" xpointer="intropara2"/>
+ <xi:include href="../../lessons/mged/learning_viewing_options.xml" xpointer="creating_radio"/>
+ <xi:include href="../../lessons/mged/learning_viewing_options.xml" xpointer="locating_viewing_info_cmd_window"/>
+ <xi:include href="../../lessons/mged/learning_viewing_options.xml" xpointer="viewing_system_elements"/>
+ <xi:include href="../../lessons/mged/learning_viewing_options.xml" xpointer="coord_sys_summary"/>
+ <xi:include href="../../lessons/mged/learning_viewing_options.xml" xpointer="view_radio_angles"/>
+ <xi:include href="../../lessons/mged/learning_viewing_options.xml" xpointer="shift_grips"/>
+ <xi:include href="../../lessons/mged/learning_viewing_options.xml" xpointer="review"/>
</chapter>
<chapter id="Lesson-3">
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