By Dennis Collin
The month of March is over, and it is that time of year when a new version of AutoCAD LT is available to download and install from our Autodesk Access App or Online Account. This post will highlight many of the new features listed.
SAME 2018 ‘DWG’ FORMAT!
The inevitable questions are what new features do I get with this new release, and will it help me save time and become more efficient? There is definitely a new look with a revamped application Icon and splash screen, but the overall interface looks very familiar once AutoCAD has loaded. The current DWG format remains at the 2018 version which will be welcome by many offices who just need to view AutoCAD drawings. It is also possible to save back to legacy R14 DWG or R12 DXF formats if required.
One of the main features that has been introduced to AutoCAD is the support of AutoLISP! This environment has been available for Full AutoCAD for many years. AutoLisp provides the ability to streamline workflows and enforce CAD standards through automation and use thousands of programs that were previously written for use in AutoCAD-based programs.
AutoLISP is based on the LISP programming language, which is simple to learn and powerful for automating design tasks. No specialized programming tool or editor is required to create or modify AutoLISP programs.
An AutoLISP program can:
- Access built-in AutoCAD commands and system variables directly
- Modify or create objects directly in the drawing database.
- Prompt the user for input at the Command prompt or with a dialog box using DCL (Dialog Control Language)
- Programs written using AutoLISP can be stored in external files and loaded into the product when needed.
These file formats can be used to store AutoLISP programs:
AutoLISP Source Code (.lsp) file—an ASCII text file that contains AutoLISP program code.
Fast-load AutoLISP (.fas) file—a binary, compiled version of a single LSP program file
Visual LISP Compiled (.vlx) file—a compiled set of one or more LSP and DCL files.
However, it should be noted there are some limitations when utilising AutoLISP in the AutoCAD LT environment.
Most VL*, VLA*, VLAX*, and VLR* functions are supported, but the use of third-party automation libraries is not supported with AutoCAD LT.
Here is a high-level summary of the functions that are not supported:
- vlax-create-object
- vlax-get-object
- vlax-get-or-create-object
- vlax-import-type-library
- vla-GetInterfaceObject
VLA* functions related to creating and modifying 3D solid and surface, helix, material, multiline objects among others that can only be created in AutoCAD.
entmake, entmakex, and entmod functions only allow for the creation and modification of objects supported in AutoCAD LT
AutoLISP functions exposed by custom ObjectARX and Managed .NET programs also can't be used.
ActiveX limitations:
- PreferencesProfiles object exists as part of the ActiveX implementation, but all of its methods and properties have been removed since profiles are not supported in AutoCAD LT for Windows
- Creation of 3D meshes, surfaces, and solids is not supported, while support is limited for the modification of 3D objects.
Developing AutoLISP program limitations:
- Visual LISP integrated development environment (IDE) and VLIDE/VLISP commands are not available in AutoCAD LT for Windows.
- Debugging with the AutoLISP Extension in Visual Studio Code is not supported in AutoCAD LT for Windows.
Deploying AutoLISP program limitations:
- MNL files are not automatically loaded with CUIx files that have the same name, but the files can be loaded using the AutoLISP LOAD function from another LISP file
- Compiled LSP files are supported in AutoCAD LT for Windows, but compiling LSP files can only be done in AutoCAD for Windows only.
- Programs that utilize functions and commands that are limited to AutoCAD should check which product they are being loaded into to avoid compatibility problems. This can be done using the PROGRAM system variable, a value of acadlt is returned for AutoCAD LT.
Like its elder full product sibling AutoCAD LT also has a new smart block functionality can offer placement suggestions based on where you've placed that block before in the drawing.
The block placement engine learns how the existing block instances are placed in your drawing to infer the next placement of the same block. As you insert a block, the engine gives placement suggestions close to a similar geometry where you've placed that block before.
For example, if you've already placed a plumbing fixture block close to a wall corner, then when inserting another instance of that same block, AutoCAD automatically positions the object as you move it close to a similar corner. As you move the block, the walls highlight, and the position, rotation, and scale of the chair block are adjusted to match the previous block instance. If this is not desired, it is possible to change options via the Ctrl key to switch to other suggestions or move the cursor away from the target area to ignore the current suggestion. To temporarily turn off suggestions when placing a block, use the ‘Shift+W’ or ‘Shift+[‘ shortcuts while inserting or moving.
Unfortunately, AutoCAD LT does not have the same smart block replace facility, although this can be possibly mitigated with the introduction of AutoLisp aupport.
The Trace environment is also improved and now includes the new COPYFROMTRACE command and new settings controls on the toolbar. The COPYFROMTRACE command allows users to copy objects from a trace into the drawing. There are also new settings in the settings menu for transparencies for both the trace and the markup.
There are also improvements in how AutoCAD interacts with Autodesk Docs, with improved support and performance when viewing large files. An improved performance with Desktop Connector and opening drawings from the Cloud.
The Start tab is also improved in this release including new options to sort and search recent drawings and Improved navigation for drawings stored on Autodesk Docs. The recent drawings list uses smaller thumbnails to allow for more drawings to display. You can now sort and search the recent drawings in both the grid and list views.
A new file tab menu replaces the older ‘overflow’ pop-out menu. It also provides the ability to switch between drawings, create or open a drawing as well as many other commonly used functions.
AutoCAD LT 2024 also has a new layout tab menu which allows users to switch between layouts, import a layout from a template as well as publish options.
Other improvement includes speed improvements in performance along with a new PDFSHX system variable when this is set. AutoCAD store text objects that use SHX fonts as hidden element when the drawing is exported to a PDF. This makes the text searchable and selectable in the PDF file.
There are also performance improvements in LT’s graphics engine, in terms of handling raster images, wipeout elements, layout switching, stability and support for large coordinate systems.
In summary there are quite a few enhancements, to existing commands, with AutoCAD LT. The introduction of Lisp along with smart block placement are probably the most noteworthy. I would also like to have seen at least some of the Express tools that come with the full AutoCAD along with its enhanced data extraction tool. However, there are certainly enough new or enhanced features which will make many routine tasks easier to warrant deploying and using the new AutoCAD LT version.
Some useful information on AutoLISP and routines can be found here:
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