Tutorial Post 10: Inputs Page.

Tutorial Post 10: Inputs Page.

You can invoke Inputs Page by pressing the sequence of two keys: 'Q' 'I'

Inputs Page is used for typing in some parameters in text input fields.
Type in the values of the parameters in respective text fields and press ENTER. You may also press ESC or 'Q' to leave the Inputs Page without changing the parameters.

Tutorial Post 9: Action Modes.

Tutorial Post 9: Action Modes.

Action mode specifies the actions of  'B', 'V', 'F' and arrows  keys. The default action mode is rotation:

 In this mode, pressing one of 'B', 'V', 'F' and arrows  keys rotates  the model  in selected direction around its focus point, which is, usually, the current cursor position. 

To move the cursor you heave to select cursor mode:

This mode is selected when the Shift key is pressed down. When you release the Shift key, the rotation mode is restored. While you are cursor in the cursor mode, the current position of the cursor is being displayed:

 (The simplest way to see the current cursor position is to press the Shift key. Note that after releasing the Shift you will have rotation mode.)

There are also action modes for moving, 90-degrees rotations, and mirroring of the selected endpoints. You can set these modes on the action modes menu which is invoked by pressing the 'A' key:

If you accidentally enter such "selected endpoints mode" while there are no selected endpoints, you may have impression that the application is not responding: 

 Just press and release Shift key to escape back to rotation mode.

Tutorial Post 8: Light.

Tutorial Post 8: Light.

The final color of the pixel on the screen is its RGB color vector multiplied by its brightness which is a factor with a value between zero and one. Edges are displayed in their full brightness (i.e. brightness=1.0). The brightness of the triangle is a sum of two components: 

• a fixed ambient component (default initial value is 0.2)
• a directional component

The value of the directional component depends on the angle between the direction of the directional light and the plane of the triangle. The more perpendicular the triangle is to the direction of of the light, the greater is the value of directional component of its brightness. 

Initially the directional light is parallel to the Z axis af the model space:

When the model is rotated, you can see the sides that are parallel to the direction of the light (they have only ambient component of the brightness):

You can set the direction of the light to the direction you are looking at, by pressing the sequence of the keys 'QDL' (i.e. 'L' key on data sub-menu):

Tutorial Post 7: Colors.

Tutorial Post 7: Colors.

You can invoke color-chooser sub-menu to select the color of the cursor ('QCC') or of the background  ('QDB'):

You can choose one of the eight predefined colors by pressing one of the keys: '0', ... , '7'.

You can also 'fine tune' each component of the color  by pressing one of its two keys. For example, the red component is increased by pressing 'R' and it is decreased by pressing 'E' (next key left to 'R' on QWERTY keyboard).

If you want to reuse  some color that is already used in the model you can select some endpoint with this color and use the 'N' key. The 'N' key cyclically selects colors from the selected endpoints. (Sometimes it is hard to select a single endpoint if other endpoints are in the same place.)

Note that the color-chooser sub-menu is persistent. To leave it, you have to press one of the keys: 'Q', ESCAPE, ENTER.    

Tutorial Post 6: Clipping.

Tutorial Post 6: Clipping.

Sometimes the fragment you want to edit is obscured by some other objects. You may use use clipping to prevent drawing the fragments that are outside  specified clipping box. 

Go to the clipping sub-menu with the sequence of key presses 'QX':

In the following example you see blue cube without any clipping:

Note the position and orientation of the cursor. When you invoke clipping sub-menu ('QX') and press the left arrow on it, then you move the 'maximum'  X coordinate of the clipping box to the X coordinate of the cursor. Clipping box is aligned with the model space. The direction of clipping is determined the same way as the direction of moving the cursor. 

Now you can see the smaller red cube hidden inside the blue one as the fragment of the blue box outside of the clipping box is not drawn.  (If you clicked 'QX' left arrow again, then the  X coordinate of the clipping box would be reset to its initial, very large, value. Arrows and 'B', 'F' keys on clipping sub-menu act as toggle switches.)

Let us press 'QX' and down arrow:

The maximum Y coordinate of the clipping box has been set to the Y coordinate of the cursor.

To cancel  clipping press 'QX' and then 'R'. (Actually, it resets the clipping box to its initial, very large  volume.)

  

Tutorial Post 5: Constructive Points.

Tutorial Post 5: Constructive Points.

Constructive points are used to denote positions in the model space. They are used mainly as the parameters of constructive methods. Constructive points sub-menu is invoked by pressing sequence of keys 'QP'.

You have the options to:

• set a point in current cursor's position'
• find a constructive point with a cursor by its name and show its label
• hide all the labels of constructive points

Constructive points are named with single letters: 'A' ... 'Z'.

In this example we select some endpoints and set two constructive points 'A' and 'B':

Then we execute a constructive method that moves the selected endpoints by the vector 'AB':

Note that the labels of constructive points are displayed as black letters on white rectangles with the lower left corner of the rectangle in the position of the constructive point. The labels are always facing the observer:

Tutorial Post 4: Selected and Bookmarked Endpoints.

Tutorial Post 4: Selected and Bookmarked Endpoints.

Many actions (painting, deleting, some constructive methods) are performed on the sets of the endpoints. The selection sub-menu is invoked by sequence of key presses 'QS':

Here you can find options for selecting the endpoints. For example, initially the default (cancelled) clipping box is so large that you can select all the endpoints by pressing 'X'.

The selected endpoints are marked by little x-shaped crosses of the cursor's color:

(Note that the actual number of selected endpoints in the example is 12, since each segment has two endpoints. If many selections are drawn in the same place then we see only one selection mark.)

Some actions (e.g. folding or triangles-triangles intersection) operate on two sets of endpoints simultaneously. Therefore  you can specify a second set of endpoints: bookmarked endpoints. You can change the selected endpoints into bookmarked endpoints by pressing 'B' on the selection sub-menu. The bookmarked endpoints are marked by little squares of the cursor's color:

Each time you bookmark the selected endpoints, the previous bookmarks are cancelled. Note that you can cancel bookmarks by bookmarking the empty set of selected endpoints.