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Illusionist

Another RISCWorld exclusive...

Edit menu

To bring up the main menu press the MENU button on the mouse whilst the pointer is in the Illusionist window. This also has the action of making Illusionist the active program, indicated by the title bar of the Illusionist window turning cream. The main menu looks like this:

The Edit sub menu is a very important one in Illusionist as it is used to add objects and lamps and also to control the materials used for objects.

Add object

This sub menu enables you to add various objects to the scene. An object is always added with its centre at the cursor position. If the Grid option has been set then the object is scaled to use the grid size. This results in objets falling within a two by two grid. For example a Cube will be exactly two by two grid units and a pyramid will be two units wide at its base and two units high. If the Grid Lock option is on then the objects are locked to the grid intersections.

Sweep object is explained more fully later but basically you can define your own object which is then plotted onto the scene. The other objects are self explanatory apart from Surface which plots a flat plane made up of intersecting lines. Any of the points can be selected and distorted so it is easy to generate contour maps.

Example 1: Click on Clear all in the icon bar menu to clear the scene. Go to the Edit.Add object menu and click on Cube. A cube is then plotted at the cursor position. Try clicking on the Rotate icons to see the cube rotating and also click into the white preview pane to see the wireframe image. Use Ctrl X to delete the cube and try plotting pyramid, sphere and torus. Try rotating these objects.

The same principle applies to Cone, Hemisphere, Disc, Surface and Sweep objects.

Delete - Ctrl X

Click on this icon or use Ctrl X from the keyboard to delete the selected objects.

Delete Pol

This option deletes the selected polygons. This is used to remove just part of an object. For example a cube is constructed from six polygons - one for each face. You can remove one polygon by selecting the points at each comer and using this option. You then have a cube with one open end, or in other words a box.

Material

This is another important item and it controls the appearance of the objects. It is in this dialogue that you can assign a picture map to be wrapped onto an object.

When you enter this dialogue the currently selected colour is shown in the colour box at the top right of the window. (Note: when using 16 colour modes the colour box only shows the nearest colour from its 16 colours.) The sliders at the top of the box are used to alter the Red, Green and Blue components of the colour. You can alter the sliders by dragging or by using the arrows on the left of each slider. Note that changes do not take effect on existing objects unless they are selected and unless you click on Update in this dialogue All new objects created take on the current settings in the Material menu.

• Enviro - This option controls the amount of environment 'reflectivity' in the selected objects. The higher this slider is set the more the colours of the sky and ground are seen in the object. This is not true reflection but you can achieve effects very close to the real thing Another way of describing this function is to think of it as setting the degree of mirroring.
  
• Textures - The five buttons Matt, Shiny, Metal, Plastic and Luminous enable you to assign different textures to selected objects.
  
• Update - Click on this icon to update the currently selected objects with the settings in the Material menu. Note that this does not include map coordinates - see later explanation.
  
• Fetch - Click on this icon to fetch the material specifications for the selected object. If more than one object is selected then the details for the first polygon which was designed are fetched. This is useful if you want to match a new object with an existing object.

The three remaining options in this dialogue are rather complicated and it is worthwhile reading the following explanations carefully so that you can get the best out of the program.

• Single F/Double F - This stands for single and double faced polygons. Each time you click on this icon it toggles between the two options. To describe this icon it is better to understand more about how the scenes are created.
  
   All objects, including spheres, are made by connecting points with flat surfaces (facets). Each facet is a polygon and a polygon can be single or double faced. The points can be seen highlighted on the three design panes, they are white when selected, otherwise they are green. To save rendering time the facets or polygons are usually plotted only if they face toward you. If you want all facets plotted then you must use the Double F option to instruct Illusionist to make the objects double faced. (See the Introduction to this manual).

Example 2: Click on Clear all in the icon bar menu and then click on Tube in the Edit.Add object menu to place a tube in the scene. If you do a Mini test on this you will see that only one side of the tube is visible as the inside of the other side of the tube is facing away from you and is therefore not visible at this angle. Next, ensuring that the tube is still selected, click on the Single F icon to change it to Double F, then click on the Update icon in the Material dialogue. This updates the selected facets with the new material settings, which now include Double F for double faced. Now do another Mini test to see that all the facets of the tube are now drawn regardless of their orientation. (See the Introduction to this manual.)

The same logic applies to the other objects in the Add Object menu although in many instances it does not appear to make sense to make objects double faced.

For example it may seem silly to make a sphere double faced as you cannot see the inside. But you can ! If you wrap a map 'onto a sphere and the map has areas of black you can make the black areas transparent so that you can see into the sphere. This is useful for doing things such as lanterns with holes that enable you to see the inside of the lantern. See the Black clear menu item for more details.

• Normal/Smoothed - Again this toggles between the two options. Smoothed gives the illusion that objects such as a sphere are made from curved surfaces. In fact, as you know, they are made from polygons. If you have Normal on then each polygon is a constant colour and it is easy to see the individual polygons. If you have Smoothed on then smoothing merges one polygon into another and it is difficult to see the joins.
  
• Selecting polygons - This is not a menu option but it needs to be explained here before you move on to the Map function. You can change the colour of a polygon by selecting all the points, choosing [he colour and clicking on Update.

Example 3: Load the Cube vector file and click on the Select all icon so ensure that all points are selected. Click on Render.Mini test to see that you have a grey cube. Go to the Edit.Material window and choose a different colour. Click on Update and then on. Render.Mini test. The cube will now be the colour that you have chosen

Move the cursor off the cube and add a pyramid. Note that all points on both the cube and pyramid are selected. Click on the Select all icon with ADJUST to de-select all points. Click on the Selector icon to get a large circle cursor and position the cursor in all three design panes over the top point of the pyramid to select it. Next click on the Join icon to link all points of the pyramid together. You can now change the colour of the pyramid without affecting the colour of the cube. Of course you could have used the Selector cursor to select all the points of the pyramid but using the Join function ensures that you get all of the points.

The above example deals with changing the colour of a whole object but it is often desirable to change the colour of just one of the polygons or indeed of each polygon in turn to a different colour.

This whole area is fundamental to Illusionist but it is a little complex to explain clearly. Please work through the following exercises to help you understand.

Example 4: Load the Cube vector file and click in the Preview pane, you can see the outline of the cube. Click on the Zoom icon with ADJUST to zoom out one step. You can now see both the Observer position (yellow cross) and the Target position (red plus). Using the bottom right design pane (plan view) you can see that the Observer position is in the South East looking via the Target position towards North West.

Now use the Edit.Material window to set the colour to blue and click on Update. Now when you click on Render .Mini test you will see that the left hand polygon is blue.

General guidelines: To select a polygon and alter the settings:

1. Decide which polygon you want to select.
2. Use the two panes that contain the direction in which the polygon faces to select the first point. It doesn't matter which point you choose from the possible choices as long as it is on the relevant side eg If the polygon faces East you can use either East/Up or East/ Down in the top right pane.
3. Use the other pane to select the points of the polygon.
4. Choose you material settings and click on Update.
5. Use Render .Mini test to check the results.

These rules are not hard and fast but should be thought of as a general guideline. For example if you are selecting polygons from a pyramid it may be easier to select the polygon direct from the bottom right pane. With a pyramid you can select any side except the base in this way. To select the base you would select the lower points in the top two panes first and all four comers in the bottom right hand pane, or plan view.

Using the cube again. You might want to select the bottom polygon. We have seen how you can select the top polygon by positioning the Selector cursor over the two top points in the top two panes and selecting the four points in the plan view. To select the bottom polygon you would position the cursors on the two lower points in the top two panes and then select the four points in the bottom right hand pane. To alter the sides of a cube it is probably best to rotate the cube and work on the polygons as they face you so that you can check the result using Mini test.

Selecting polygons on a sphere uses the same principles but it would be impossible to lay out any rules that would make any sense on reading. This is one of those instances when playing is far better. The guidelines given earlier will help you to understand. The main points to remember are that to select a point the cursor must be over the point in all three panes. If you select a point in error you can use the De-Selector option (Ctrl D) to erase specific points. The De-Selector cursor is a large circle with a diagonal line passing through it.

It is essential that you understand how this function works if you are to get the best out of Illusionist. For an exercise try placing a double faced tube and colouring some of the polygons a different colour.

• Map - This is another complex function that is worth persevering with. Maps must be either Mode 12 (16 colour) or Mode 13 (256 colour) full screen sprites. They are loaded by pressing Ctrl P to bring up the Picture maps window. When the window is up you can drop any Mode 12 or Mode 13 screen into the list. All sprites are held internally as a square image consisting of 1024 by 1024 cells. This enables you to rotate a map without distortion.
  
   After loading a picture map you can assign it to a whole object or just the selected polygons in the same way as assigning different colours to polygons. You select a map instead of a colour by clicking on the box to the right of the word Map in the Material window. This toggles through the loaded map numbers. Once a map is chosen click on Update to assign the map to the selected polygons. Now when you render the picture the map is put onto the polygons.

Example 5: Load the Cube file again. Press Ctrl P to bring up the Picture map window and drag the file Mandril into the window. Go to the Edit.Material window and click on the Up arrow beside Map so that the number one appears in the panel. Click on Update and then on Render.Mini test. You will now have the ape picture mapped onto each side of the cube. Each polygon is mapped with the selected picture map.

Delete the cube and add a sphere to the scene. Now map the picture onto the sphere in the same way. This time you will see that the picture is mapped onto the whole object and not onto each polygon. The same is true of Sweep objects where they are treated as one object and have the picture mapped onto the whole object.

Cubes, pyramids and discs have the picture mapped onto each polygon by default. All rotated objects such as the sphere, hemisphere, tube, torus, surface and sweep have the picture mapped onto the whole object. For example if you had a picture of the map of the world you could map it onto the sphere and you would get the earth.

If you prefer you can select just one polygon from these other objects and map the picture onto the individual polygons.

Next to the map number in the Material window is a set of Map coordinates. These are used to decide what part of a picture is mapped onto the object or polygon. Remember that all picture maps are converted internally to 1024 by 1024 cells. The coordinates let you specify which part of the picture is mapped onto the polygon

If you want the whole picture mapped onto the polygon then you use the default coordinates: 0,0,1023,0,1023,1023. You only need to give 3 points as the program works out the fourth one for you.

Example 6: Clear the vectors using the icon bar menu. Press Ctrl P to bring up picture map list and drop the supplied picture map called Mandril into the list. Using Edit.Add object place a cube on the scene. Go to the Edit.Material window and select Map number 1 and click on Update. Now render the whole picture using Render.Draw picture. You will see that the picture of Mandril the ape is shown on all visible sides of the cube in full. To confirm that all of the picture is used click on Mandril in the Picture map list. Note that the Mandril picture is sideways in the original.

Click on Render.Draw picture to see the image drawn as above. In the above example the points are cropping part of the picture so that only the portion shown is used to map onto the polygons.

Hint: If you are finding this difficult to visualise take two sheets of paper and in one cut a large square the same size as the photograph on the front of the manual cover. On the second sheet draw a square the same size as the first square but cut out a square about half its size. At the bottom left corner of the large cut out square and the large drawn square on the other paper mark Point 1 (0,0),' at the bottom right mark Point 2 (1023,0) and at the top right mark Point 3 (1023,1023). Now position this over the photograph with Point 1 at the bottom left of the photograph. Now use the other piece of paper with the smaller square and position Point 1 at the bottom left of the photograph. Because you have a smaller square you can only see part of the photograph. If the hole is half the area of the larger hole these coordinates would be 256,256,768,256,768,768.

If you want to rotate a map you simply change the starting point for Point 1. For example to rotate the Mandril map so that the ape appears upright you would enter the coordinates 1023,0,1023,1023,0,1023 - try it but don't forget to press <Return> and click on Edit.Update.Map co-ords before drawing the picture.

Tiling

If you use larger coordinates then the map is tiled onto the polygon. For example if you enter coordinates 0,0,2047,0,2047,2047 then you get four maps on each polygon. If you enter 0,0,4095,0,4095,4095 then you get sixteen maps on each polygon.

You can alter the coordinates to distort or tilt maps. For example using a cube and the mandril map try 0,0,2047,0,4095,8191. the possible combinations are almost unlimited.

Triangles

Mapping onto a triangle is exactly the same as mapping onto a polygon on a cube. You supply three coordinates as before and the relevant part of the picture is mapped onto the triangle. Note that the image is not squashed into the triangle. The triangle simply provides a window onto the square map.

Update

The Update menu is a special form of the Update icon in the Materials menu. It is used to update just the specified item whereas the icon in the Materials menu updates everything, with the exception of map coordinates. The alI/no Co-ords option is the same as the Update icon in the Materials menu.

Selecting Map co-ords from this menu is the only way to update the map coordinates entered in the Material menu. Clicking on this item actions the changes as entered in the Material menu.

Do

The Do menu contains four items that do not have logical homes in any other menu.

• De-sel (Ctrl D) - This brings up the De-selector cursor which is a circle with a diagonal line through it. If you position the cursor over a point in all three windows then that point is de-selected.
  
• Attract (Ctrl A) - This brings up yet another type of cursor. This one looks like a magnet and it is used to 'attract' selected points thus enabling you to distort objects. You use it by selecting some points, bringing up the Attract cursor and then pressing ADJUST whilst holding down SELECT. SELECT works as normal and moves the cursor around but when you also press ADJUST the selected points are 'attracted' to the magnet cursor. The closer a point is to the cursor the faster it is attracted towards it. If the point is more than 3/4 of a view window away from the cursor then it does not move.
  
   The amount of movement is relative to the view window size. To affect more points use the Zoom out option to see more points before using the Attractor. This is an extremely useful function and it was this that enabled us to produce the superb dancing Coke can demo that many of you will have seen.
  
• Invert - This item inverts the face of all selected polygons. Remember that if a polygon is single faced and facing away from you that it is not visible. This option inverts the polygon so that the other side faces you and is therefore visible (or invisible depending on the position before inverting).
  
   This is useful to create a room where all you need to do is place a Cube, position the Observer position inside the cube and the Target outside. If you look at the wireframe after doing this you see nothing but if you click on Invert and the look at the wireframe you are inside the cube.
  
• Extrude WE - This option enables you to extrude selected polygons in a Westward direction. All points on the relevant polygon must be selected.

Example 7: Clear the scene by clicking on Clear all in the icon bar menu. Next create a triangle polygon as described in the section on the Polygon maker on page 14. When you have done this click on the Extrude WE item once. All the points of the polygon are extruded West. If you do a Mini test you can see that the object is a solid wedge shape. Whilst you can extrude again it does not make sense to do so as you can elongate objects by scaling. Nor does it make sense to extrude 3D objects.

Lamps

This dialogue controls the lamps, or lights, that are used in a scene. They show on the scene as small grey filled circles with a number beside them. You can have up to 14 lamps in a scene. The colour of the lamp is controlled with the Red, Green and Blue sliders. Any changes take immediate effect.

• Lamp number - You can scan the currently defined lamps by clicking on the left and right arrows next to the lamp number. As each lamp is selected its attributes are shown in the box.
  
• Create - To create a new lamp click on the Create icon. The new light has the attributes set in the menu but these can be altered at any time.
  
• Type - There are two types of lamp Point and Spot. Both are shown as filled grey circles. This icon toggles between the two. Point lights shine in all directions whereas Spot lights have cones of light with any width, or spread, and can be directed at any angle. When a spot light is selected a grey outline circle with a number the same as the lamp appears in the scene - this is the target for the spotlight. It is usually placed at position 0,0,0 but can be altered with the Put target option (see below).
  
• Spread - This is a writable icon and to alter it you click in and edit the numbers. The number gives the spread of the spotlight's cone of light and is given in degrees.
  
• Distance - This is another writable icon and it sets the number of distance units over which the light fades out to nothing. If it is set at 1000 then the intensity of the lamp is full until the object is over 1000 units away. Its intensity is then gradually reduced until, at 2000 units, the intensity is zero. Note that if the distance is set at 100 the intensity fades to zero at 200.
  
• Position - Clicking on this icon causes the currently selected lamp to be placed at the current cursor position.
  
• Put target - Clicking on this icon causes the currently selected spotlight target (a grey outline circle) to be placed at the cursor position. Note that the distance of the target is irrelevant as the target only provides directional information.
  
• Delete - Click on this icon to delete the currently selected lamp.

Sweep

This useful edit window allows the definition of rotated or swept objects. This window is used to define the silhouette of an object, like designing it on a lathe. To demonstrate the results of the sweep function find the supplied Sweeps directory on the disc and drag the Glass file into Illusionist. Now look at the Sweep window again you will find the silhouette of a glass. Now select the menu item Edit.Add object.Sweep Obj which places the glass in the scene with all the other objects. Click on the Clear icon to wipe the glass sweep.

Designing a Sweep object

All points are placed in the right hand side of the window (gridded). The left hand window automatically shows a reflected copy of the right hand side.

• The SELECT button places points.
  
• The ADJUST button back-tracks through previous points for editing.
  
• The Delete icon deletes the last or edited point.
  
• The icon shown as Open above toggles between Open and Joined when clicked on. When set to Joined the last point on the sweep is joined to the first (see the Nut example).
  
• The left hand icon, set at 360 above, defines the number of degrees of rotation that the sweep makes when the object is created. This is demonstrated later. Clicking on the Up and Down arrows increases and decreases this by preset amounts.

Note: When creating a sweep silhouette, place the points in a clockwise direction. This ensures the facets face outward when the object is swept.

Hint: To make sure that a point is in the exact centre vertically move the pointer into the left hand side of the designer and press SELECT. The line never crosses into the left side but it will move as far left as it can go, which is the centre.

Example 8: Clear the current sweep and load the example sweep file called Tape. Look at the simple design in the weep window and note that the degrees of rotation is set to 1080. Click on the Grid item in the Misc menu - a grid should be visible on screen. Next go to the materials window and set Red, Shiny, Smoothed and Double F. Now click on the Sweep obj in the Edit.Add object menu to create the sweep object. You will notice from the grid that on each turn of the sweep the points are moved up by one grid unit until the desired 1080 degrees of rotation are completed.

Try changing the degrees of rotation by clicking with SELECT and ADJUST and the placing the sweep object again.

This function is very useful for creating symmetrical objects and when used with the rotation it is very useful for creating curled wire or exotic sculptures!

Connect

This function joins together all selected points that have the same coordinates. this reduces the number of points required and consequently reduces the file size. For example if you put Grid Lock on and place two cubes one on top of the other so that the top of one is touching the bottom of the other. You can select all points and then click on Connect to join the points on those that are at the same position. If you check the File info box on the icon bar menu before and after you will see that the file size has reduced.

This command also proves useful for the smooth shading function. For example if you put two smooth shaded hemispheres together the shading does not work correctly over both objects unless you connect the points of the two halves together using this function.

Note that this process may take a little while on complicated scenes.

Copy (Ctrl C)

This function copies all selected polygons. There is no immediately visible effect as the copied object is positioned over the original. The original points are de- selected so you can then move the new object to the desired position using the Mover. Alternatively you can use the rotate icons to rotate the object.

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