The commands explained in this section are used to control the display of the building steps of the model in work. They are ignored in any mode except in the "View mode".
Building steps stop the drawing during viewing on defined positions, allowing the child (or adult) to build the model step by step as known from building instructions of Lego.
The simplest form is the normal step. It just stops drawing and waits for an input until the drawing is continued. When looking into the "model part list" everything above the step will be executed or displayed. Everything below the step will happen after the user continues drawing, by pressing a key or one of the buttons on the "Movement bar".
To insert such a step navigate to the position where drawing should stop, using the "model part list". The step will be inserted after the item currently selected.
From the menu select "Edit/Insert/Step", or press the corresponding button from the toolbar.
MLCad can insert steps for you based on certain criterias. Open the following dialog using the menu "Edit/Add/Autosteps...":
![]() |
- "Insert step after height change" inserts a step between parts with different Y (height value). - "Insert step after number of parts" inserts a step after a the number of parts specified below |
Note: this feature is usefull in connectionwith the sorting function to automatically create building instructions for a model where the model is build from bottom to top. See also Sorting.
Rotation steps are extended forms of the simple step command (see above). They also stop drawing, but before, they rotate the model. Therefor it might make sence to insert a normal step before a rotation step, this will stop drawing at the current angle, wait for the users input, rotate the model and wait again.
The simplest form is the "rotation end step" which turns the model back to the default 3D display angles as defined in the "Settings". To insert such a step navigate to the position where drawing should stop, using the "model part list". The step will be inserted after the item currently selected. From the menu select "Edit/Insert/Step", or press the corresponding button from the toolbar.
The more interesting form is the "rotation step" itself. It allows to display the model from any side. Insert such a step as any other step (see above) but use the "Rotation Step" this time. The following dialog will be displayed now:
The fields X, Y and Z accept degree
values in the range from -360 to +360 degrees. Select one off Relative,
Absolute or Additive to set the type of rotation
step. Relative turns the model relative to the default
view angle, while Absolute would overwrite these angles.
The last type "Additive" turns the model based
on the current angles when this step is executed. Press the Preview
button to look at your model at this angle. Press the OK
button to save the rotation step.
Note: Due to the fact that MLCad doesn't know the right
rotation angles at this time, preview for Relative is
disabled.
Instead of entering the angles you can also click into the preview and while holding the left mouse button you can rotate the model with the mouse.
You can define more steps after each other. For instance if you want to stop drawing at a certain point, rotate the model add new parts, stop drawing again, and at the end you rotate the model back. Here is how you would do it:
1) Add parts to the model
2) Add a normal step to the model
3) Add a rotation step to the model, to rotate it into the angle
you like
4) Add some more parts
5) Add a normal step (this will cause drawing to stop with the
changed view)
6) Add a rotation end step (and the model will be displayed in
the default view)
Another example for using the rotation steps is to rotate the model along an axes to show it when it is complete:
1) Create the model
2) Add the first rotation step (e.g. X and Z set to 0, and Y set
to 90°)
3) Add another rotation step (e.g. Y set to 180° now)
4) Add the last rotation step (e.g. Y set to 270°)
When you view the model, the program will show the complete model at the end and then rotate it by 90° steps when you step through
The clear command when it is executed clears the current screen and leaves an empty screen back, everthing drawn before this command is invisible after it.
To add a background image either select from the menu "Edit/Add/Background" or select the background symbol from the "element bar". In either case a dialog is opened where you can select the file to be used as a background. The image will be shown in this dialog. Please note that true-color bitmap files can be used only!
You may assign one or more background images for your model. The background image will be displayed in the viewing mode. If you add exactly one background image to your model and it is before the first step command (in the "model part list") then it will be shown for all steps displayed during viewing. If you define the background image after a step, it will be shown in the next step following the image line.
You can use more than one background image by specifying different images during steps, if there are more background definitions in one step the last definition will be used.
Examples:
In the following example the background is shown always
0 Comment
0 BACKGROUND "xxx.bmp"
1 ....
1 ....
0 STEP
In the next example the background is the default background color (no image) until the first step, then the background image is shown
0 Comment
1 ....
1 ....
0 STEP
1 ....
0 BACKGROUND "xxx.bmp"
1 ....
This feature is used in connection with the "Buffer Exchange commands". If buffer exchange commands are used in sub-models of an MPD project, than we expect the final sub-model beeing used in the main-model. But the sub-model also shows everything inbetween two buffer exchange commands, even if the sub-model itself when viewed doesn't show them.The reason for this effect is that MLCad disables CLEAR and Buffer Exchange commands in sub-models. Another problem occures when the project is viewed with another viewer other than MLCad itself.
These problems can be solved by so called Ghost Parts or Ghost Items. The main idea behind Ghost Items is that they are viewed only if the model which contains them is currently viewed, but not if it is viewed as a Ghost Part. Other viewers (than MLCad) will not display the Ghost Parts at all, since they are stored in the format of a comment, so other viewers would interpret them as plain comments.
To create Ghost Parts simply select the relevant parts and either select the menu "Edit/Visibility/Ghost" or press the corresponding button in the tool-bar. The menu "Edit/Visibility/Ghost Off" reverts the item back to a normal item.
For examples of using this feature please see the example models on my web-page.
This group of commands allow to influence the viewing-mode only and can be used to insert certain effects during viewing.
The Clear command when executed simply clears the displays, any parts shown before will not be shown after this command. As special use of this command is to use it for a slide show.
The Buffer Exchange command is a very powerfull command. MLCad allows to save up to eight displays during the viewing mode and to retrieve them at a later moment.
To use the command select the menu "Edit/Add/Buffer exchange" or use the tool bar button instead. Then the dialog shown below is displayed:
First select a buffer to be used then check the Retrieve box when you want to restore a saved situation. An example should make everything clear:
1) Add some parts
2) Add a Buffer Exchange command, select Buffer 'A' and leave the
Retrieve box unchecked.
3) Add a STEP
4) Add some more parts
5) Add a STEP
6) Add a Buffer Exchange command, select Buffer 'A', this time
check the Retrieve box.
What will happen in View-Mode? First
MLCad will display the parts added in step 1 and stop drawing.
In the next step the parts added in step 1 and step 4 will be
shown and drawing stops again.
In the next step MLCad will retrieve the display as it was at
step 2 and therefor just display the parts added in step 1.
A nice usage of this function could be to display a certain part above the the model first, and in the next step inserted into the model (means you would add the parts from step 4 as step 7, but in a different position).
Someone might say this effect is possible with the clear command as well. True but in this case the parts displayed over all steps would have to be copied, which makes the file bigger and also slows down drawing. The buffer exchange commands eliminates the copying by hand, and makes the operation more clear.
There are several options which influence the behavior of viewing a model. Information about how to change these settings can be found at "Changing settings". Here is a summary of the options: