3D Images/3D Images.iso/programs/amiga/icoons/doc/tutorial.doc

Text File | 1995-01-12 | 7.3 KB | 151 lines

This is a short tutorial to ICoons. Follow the steps below to create a
very simple object.

Start ICoons by typing ICoons from the CLI. You should now see a screen
with 4 views labelled X, Y, Z and P. These views will show the object from
different directions.
The P view shows a perspective view of the object, when you start the
program, the perspective view will be exactly the same as the Y view;
we'll try to rotate the perspective view later.


First we'll create a closed spline:
  Select the add command by typing 'a' on the keyboard, you should now see
  the text 'Add' in the menu bar; this indicates that you now are in add
  mode.
  Point near the upper left corner of the Y view, and press and hold
  the left mouse button. Drag the mouse pointer to the upper right corner
  of the Y view and release the mouse button.
  You have now created a simple spline consisting of one segment and two
  knots. The segment is red and the knot is yellow because they're selected.

  We'll now add a third knot to the spline:
  Select the 'a' command once more, then point just right of the rightmost
  knot in the Y view, and press and hold the left mouse button.
  Drag the mouse pointer to the lower right corner of the Y view and release
  the button.
  Now you've added another knot to the spline, ICoons didn't create a new
  spline because you pointed near an existing knot, the new knot was added to
  the end of the spline because you pointed AFTER the last knot.

  Ok, lets add a knot more:
  Select the 'a' command once more, then point just below the newest knot in
  the Y view, and press and hold the left mouse button. Drag the mouse pointer
  to the lower left corner of the Y view and release the button.
  With a little luck, you now see a spline consisting of 4 knots and 3
  segments.

  Lets finish this spline by closing it:
  Once more, select the add command. This time add a knot left of the lower
  left knot. Keep the left button down, and move the new knot up to the
  first knot you created in the upper left corner.
  While keeping the left button down, click once with the right button.
  This tells ICoons to connect the two knots to each other, the result
  should be a closed spline.

  Try to zoom out by using the Left-Amiga+O shortcut (or by choosing Zoom out
  from the display menu), you should now see a nice oval.

  Unfortunately, the oval would be invisible if you tried to render it,
  this is because an area enclosed by a single spline is invisible, so
  lets make it visible now. We'll do that by adding another spline.

Spline 2:
   Ok, we want to create a spline consisting of a single segment, the
   new spline should run from the upper left corner to the lower right
   corner.
   Do this by selecting the 'a' command and point to a position near the
   upper left corner which isn't too near to the know we already have there.
   If you are too close to that knot, you'll just add a new knot to the
   existing spline. If you do that, then delete it by pressing the 'd'
   key (d for Delete!).
   Add the new spline, and drag one corner to the lower left of the view.
   Now you should see two splines in the view, we now want to connect the
   two splines to each other:

Connecting:
   Point to the lower left knot of the new 2 knot spline, press
   the left mouse button and drag it to the other knot in that corner.
   Don't release the left button yet, instead click on the right button.
   This should connect the two knots in that corner. Verify this by moving
   the (now only) knot in the lower left corner: The two splines should
   both follow the mouse when you move it.

   Now connect the splines in the upper right corner by repeat this
   procedure. The result should be a single object consisting of two
   'patches', we'll now try to render it.

Rendering:
   Select the render command by either pressing 'r', or by choosing the
   menu item 'Render'. You should see a lot of messages in the menu bar,
   and after some time, you should see a rendering of the object in
   the perspective window. When you've finished looking at it, press
   the space bar to return to the normal view.

Perspective view:
   Ok, lets try to rotate the perspective view a bit.
   Select 'Rotate P.' from the menu, or press the 'R' gadget which can be
   found left of the perspective view.
   You should now see the message 'Rotate P.' in the menubar. Point in
   any view, and press and hold the left mouse button. Now try to move the
   mouse. You should see a bounding box which will turn as you move the mouse,
   release the mouse when you're satisfied with the new position, and
   the perspective view will be redrawn.

Re-rendering:
   Since we haven't modified the object, we can render it again by using
   the Re-render command. Press 'R'  (or select Re-render from the menu)
   to see a rendering of the object from the new direction. You could
   also use the render command again. The only difference between the
   two commands are that the Render command will recompute the object
   while Re-render won't.

Configuration parameters:
   The rendering may look a more like a polygon, than like a surface
   surrounded by smooth splines. The reason for this is that the splines
   are converted into straight line segments before rendering. If the number
   of line segments per spline segments are small, you'll get an edgy
   rendering:)
   Lets change this by modifying the number of line segments per spline segment,
   this is done in the configuration window:
   Select Configuration - Edit from the Project menu, you should now see
   a window with some numeric gadgets. We'll concentrate on the two gadgets
   in the middle column.
   The "Spl. resolution" defines the number of line segments used when editing
   in the views. The "Patch resolution" defines the number of edges used when
   rendering the object (it is also used when generating a TTDDD description
   of the object).
   Try to set the Patch resolution parameter to 10 (it is probably 4 right now).
   Now select the Ok gadget to return to the previous view.
   Render the object again by using the Render ('r') command, Re-render won't
   do now because we want to recompute the object.
   The result should be a much smoother object.
   Be warned: The number of triangles in the final object is proportional to
   the square of the Patch resolution parameter. So you've increase memory
   consumption and computing time drastically by increasing this parameter.

Expanded view:
   This isn't exactly a fancy object, but it's the best we've got, lets
   finish by having a BIG rendering of the object:
   Select the 'P' gadget to get a expanded version of the Perspective view.
   Now select Re-render (or Render) to get a big rendering of the object.
   Press space when you've finished looking at this fantastic picture :)
   Return to the 4 view screen by selecting the 'B' gadget.


Generating a TTDDD file:
   Lets finish by generating a TTDDD file of the object.
   Now select the "Generate - TTDDD format" from the project menu. You'll
   now see a file requester; enter a filename, select ok and hey presto,
   after a little time you have generated a TTDDD description file of this
   fine object.

   If you want to turn this into an Imagine object, you now need the T3DLIB
   shareware package from Glenn Lewis.

Quitting:
   I'll leave "Quitting the program" as an exercise for the reader :)


   Helge