About

Blender takes a different approach to scene generation than does POVRay. Rather than programmatically defining scenes, blender allows graphical manipulation of object primitives. This guide will touch *very* briefly on using blender to create the highly imaginative (ha) ray traced stonehenge scene (or thereabouts -- the actual Stonehenge looks vastly different than a circle of cookie cutter blocks).

Requirements

Blender requires somewhat beefier hardware than does POVRay because of the interactive nature of the application. Though technically not absolutely required, it is a good idea to have an OpenGL supported video card. For comparison purpose, my Blender workstation is a 500MhZ AMD K6-2 with 512M RAM and an ATI All-In-Wonder AGP video card. Mandrake 8.0 detected the card without problems. The example scenes took anywhere from 1 minute to 1 hour to render.

Setup

Blender is available from http://www.blender3d.org. Recently, Blender has been made available with a GPL license! Installation is relatively simple and requires that the blender binary be placed in your path.

Usage

The initial blender screen at first seems imposing. It does take some experimentation to understand the interface, but after a few hours, the commands make sense. The main thing to remember is that keyboard and mouse are used in conjuction and where the pointer focus is determines what each keyboard shortcut does. The commands are case sensitive.

From the main screen, use the numeric keypad to shift the viewpoint. Note that the observer viewpoint is different from the camera view. Pressing the 2/4/6/8 keys will rotate the view. Pressing Num-5 will toggle the Perspective mode. 1/3/7/9 will align the view along an axis. +/- will zoom out and zoom in.

Next, try some of the various toggles from the keyboard. For example, [SHIFT][D] will change the drawing mode. If you don't have hardware accelerated video then using line mode will save some time.

Other keys that will be useful include:

SPACE	Main menu
TAB	Toggle Edit Mode
b	Bounding Box Selection
c	Center Image
d	Change Drawing Mode
e	Extrude
g	Grab Object
i	Insert
n	Rotation
q	Quit
r	Rotate
s	Scale
t	Texture
v	Vertex Paint Mode
x	Erase Selected
z	Toggle Solid/Wireframe
z	Toggle Solid/Wireframe
D	Duplicate

Now that you've gotten accustomed to the interface, we can try to recreate our Stonehenge scene.

1. Create a stone block
   • Start by clearing the blender workspace and centering the view above the plane. Make sure that the mouse pointer is in the image area (top) section of the screen. Delete any existing objects by pressing [x] to bring up the Deletion menu, then select All to delete everything.
   • Change to the overhead view by pressing [NUM-7]. Change to the orthogonal mode (i.e., non-perspective view) by pressing [NUM-5]. It won't be immediately obvious if there's nothing on the screen, but you'll notice that the camera (that little triangle on the screen) is no longer a 3D wireframe. Also, the toolbar icon will change.
     
   • Bring up the main Blender menu by pressing [SPACE]. Select "Add"|"Mesh"|"Plane" to insert the first object onto the screen.
     
   • A square will appear on the center of the display.
     
   • Toggle the view to the front, along the X axis by pressing the [NUM-3] key.
     
   • The corners of the plane should automatically be selected. That is, the control points will be highlighted in yellow rather than in the pink, unselected color. If they are not, select all points of the plane by using the [B]ounding box function, dragging the Selection Rectangle over all points. Then press [E] to bring up the Extrude menu. Without clicking the mouse button, drag the points along the vertical axis about 6 squares, aligning the edges along the grid line. When you are satisfied with the height, click the left mouse button to commit the change.
     

     HINT: Press the [ESC] key to exit the function without committing the action.

   • You should now have a rectangular solid on the screen. To get a better idea of the object, select the OpenGL drawing mode by pressing the [d] key. Then use the 2/4/6/8 keys on the Numeric KeyPad to rotate the views. After a few hours of this fascinating entertainment, press the [NUM-3] key to return to the frontal view. Press [NUM-5] to turn off the perspective mode to make it easier to manipulate the objects.

2. Create a Trilith

   • If all points on the newly created block are not selected, use the bounding box selection tool by pressing [b] then selecting all points. Press [D] to duplicate the block.
   • Move the block elsewhere on the screen, aligning the bottom edges of both blocks.
     
   • Duplicate the block again to create a capstone. Move this new block to an unused part of the screen. Next, rotate the capstone into proper orientation by pressing the [r] key. Align the capstone lengthwise along the horizontal axis. Press the mouse button to commit the rotation.
     
   • Once the capstone has been rotated, move it into place with the Grab tool. Press [g] to grab the capstone then place it above the two existing blocks. Make sure that there are no spaces between the blocks and capstone. Of course, if you believe that supernatural forces or alien beings levitated the rocks into place, feel free to leave the gap.
     
   • Group the blocks.
     

3. Save/Load the File

   Here's a good time to save the image in case something catastrophic happens and you need to back up to an earlier version. Go to the File menu and select Save. Type in a name. Press [NUM-ENTER] to save the file. If you need to return to a previous version, type CTRL-O then TAB to return to edit mode.

4. Create the Henge
   • Switch to the overhead view by pressing [NUM-7]. Align the middle of the trilith at the center then move it up about 10 to 15 units above the center . If your screen is not large enough, zoom out or zoom in using the [NUM-+] or [NUM--] (plus and minus) keys.
     
   • Switch to the edit mode by pressing [F9] or the corresponding toolbar key.
     
   • In the middle of the screen are the DEGR and STEPS buttons. Change the values to 360 and 8 respectively by clicking and holding with the mouse button then moving the pointer left and right. Single clicking will step through the values.
     
   • Next, press the SPIN DUP button to duplicate and spin the image. The values from DEGR and STEPS specify that the selected image will be spun a full 360^o in 8 steps. This evenly spaces out the trilith objects at 45^o.
     

   • Use the rotation keys to view the scene from different angles. If you're unhappy with the spacing, revert to your saved version and try different parameters to the Spin tool. The most important thing is to experiment with the options.

     
5. Add the ground Press [SPACE] to bring up the Insert menu. Add a plane. Subdivide it randomly. Make it cover the plane by stretching.
6. Add lighting lorem ipsum movum seclorum. Ipso facto. Civilli deredego, fortibus es inero. Novilli demis trux. Vadis inem, causen dux.