torad manual

Torad Manual Page

Description
Installation
Loading
Interface
Options
Details
Diagnostics
Environment
Files
Requirements
Caveats
Bugs
Author
Acknowledgements
See Also
Legalese

NAME

torad.lsp - Export facility from Autocad to RADIANCE scene description.

DESCRIPTION

Software extension for Autocad to export data to the RADIANCE light simulation package of the Lawrence Berkeley Laboratory.

Autocad entities can be selected and filtered by a series of options.

Entities will be sorted by one of the three criteria color, layer or insertion layer of blocks (toplayer) according to your choice. The sorting results in seperate files written for every layer or color. Other files created optionally can contain initial material definitions (all identical), a list of "!cat" commands to include all the information to make up a complete scene description, a setup of natural lighting, a view description and a makefile for automatic image creation.

Only the entities that are visible (that is their layer is on and thawed) will be exported, even when nested in a selected block. This gives you another method of filtering elements of your drawing especially usefull when you want to update only part of a scene.

The layername or color number will be part of each respective filename to make it an unique identifier. The pipe character "|" used by Autocad within layernames associated with externally referenced blocks, as well as the dollar sign "$" are replaced by an underscore "_" as they are illegal or at least confusing characters for filenames on most systems.

INSTALLATION

Torad.lsp can be loaded after you have copied the *.lsp/bi4, torad.dcl and torad.mnu/x files to a location on your host which is included in your Autocad search path. The method to specify or modify the necessary environment variable ($ACAD) varies depending on the operating system. You will have to quit and restart any Autocad still running for the change to take effect.

LOADING

Load the program by entering (load "torad[.bi4]") at the Autocad command prompt or automatically by activating the TORAD section in the screen menu area of the associated menu file. It is recommended to use compiled code which runs significantly faster. Autolisp files compiled with the compiler "acomp(.exe)" from Autodesk for extended Autolisp usually have the extension "*.bi4". The menu file associated with this program tries to load such files first if they are present and supported by your version of Autolisp. Otherwise the uncompiled lisp files are loaded.

INTERFACE

The program is called by typing "torad" at the Autocad command prompt or by selecting the "EXPORT" option in the associated screen menu section.

There is a dialog box for Autocad 12 or later(?) which controls all the necessary settings. For earlier versions the same control is provided by text input or a screen menu section.

There are a number of toggles to switch on or off by entering "Yes" or "No" in text mode or by selecting toggle buttons in the dialog box. Some of the toggles affect the access to some of the others as it is apropiate for writing only subsets of the possible data. In such a case the respective prompts will be skipped or its input facilities in the dialog box will be greyed out and so disabled.

The entity sampling and sampling mode options can be preset from the screen section of the associated menu file. They are remembered for the current Autocad editing session.

The dialog box looks as follows (in OpenWindows style):

OPTIONS

Write Filetypes

Geometry information

This switch is on by default for it is the generic purpose of the program. Turning it off will disable the list of sampled entity types and the master control file, makefile and material file generation switches since they all don't make sense without.

Master Control

The created file will contain all the necessary references to the rest of the data so that "oconv" will be satisfied with only this control file as its single argument. This and the switches for materials, viewfile and sun are off by default because you probably only want to use them when you export a complete drawing for the first time.

Since it is not the goal of torad.lsp to make a full front end to the RADIANCE package it will not maintain any of these files. The information allready in there will be lost if you create them new for every update of a part of a scene description. In such a case you will have to edit these files manually to keep them up to date.

WCS Rotation from East to X: If your Autocad model is not aligned geograpically (so that the X axis points towards east and the Y axis to north) then you can specify the difference as a rotation angle around the Z axis in degrees here. This will cause the sun definition (if any) to be loaded with the apropriate "xform -rz ..." compensation.
Makefile: The makefile will contain rules for octree conversion, preview with rview and batch calculation with rpict. Only minimal parameters are included to the commands so you will have to edit this file as well, be it for high resolution image generation or other customizations.

Materials

All the layers or colors of the exported objects will have the same material (a grey plastic) assigned whithin a seperate file generated if this option is set.

View

This option enables a pop up list which contains the views that have been saved previously in Autocad and the current view. The one you select will be written to a file similar to those written by rview which will then contain all the information like viewtype, point, direction, angle and view up vector. View angles larger or equal than 120 degrees will generate a hemisperical fisheye view. Please note that RADIANCE clips every polygon that reaches behind the viewpoint. This is often the case in parallel views exported from Autocad where the viewpoint may be at a very small offset from the world origin.

Sun at position and time

This option will prompt you for the parameters of natural lighting as required by gensky. The default values are for Zurich (Switzerland) in the afternoon of August the 1st (This may seem exotic to you but not to me).

Sampling modes

Sample entities by

Color: The Autocad colornumber as visible on the screen. This is the default and will help you when you organize your drawing "visually".
Layer: The layer of every subentity (the one which this entity is created on). Choose this method if you use a conceptual layering system independently from screen display colors.
Toplayer: As above, except for entities within blocks which will be treated as if beeing on the layer the block is inserted on. Nested blocks will end all in the same file associated with the layer of the outermost block. This can be useful if you combine the use of (unnested) block libraries with a seperate layer structuring system.

The concept of floating layers and colors within (nested) blocks is fully supported. That means a subentity within a block with the layer "0" and/or the color "byblock" will appear on the layer and with the color of the containing block. This continues recursively if the block has those properties as well until a level with explicitly defined properties or the top level block is reached. Freestanding entities with the color "byblock" are drawn with color nr. 7 (white).

Segmentation per circle for arcs

Arc entities and arc segments of polylines have to be segmented for the use in RADIANCE. The value you enter here specifies how smooth these segments will appear in the final image. Higher values will make smoother surfaces. The default of 16 is rather low but is set for reducing filesize. Make tests for optimized settings because the appearance of the segments will depend as well on the applied material as on the radius of any specific arc.

Sampled Entities

The following switches (the left boxed row in the dialog box) let you specify which entity types you wish to extract from your drawing and what kind of surface they should display. By default all entities that make up a surface in Autocad (recognized by the hide and shade/render commands) are switched on. Others that just simplify modelling but are rendered differentely in Autocad or in RADIANCE are off and have to be enabled by the user explicitly. All polygons should keep their orientation as created in Autocad determined by the right hand rule as explained in the RADIANCE tutorial. Entities extruded by thickness will be inverted if their thickness value (or "PDSIZE" for point entities) is negative.

Planarized faces of 3DFACEs: 3dfaces will be split to two triangular polygons if not planar.
Extruded and flat TRACEs: Traces will appear as a single polygon or as a box if the thickness is not zero.
Extruded and flat SOLIDs: Solids will appear as a single polygon or as a box if the thickness is not zero.
Extruded and flat CIRCLEs: Circles will appear as a ring with a inner radius of zero or as a cylinder/tube with a ring at either end if their thickness is different from zero.
Extruded faces of ARCs: Arcs with a thickness different from zero will be segmented according to the given number of segments per full circle.
Extruded faces of LINEs: Lines with a thickness different from zero will appear as a single polygon.
Extruded faces of 2D-PLINEs: 2d-polylines with a thickness different from zero will appear as a set of polygons.
Constant Width of 2D-PLINEs: 2d-polylines with a starting width different from zero set in their header entity (not the vertexes!) will appear as a polygon following the trace of the polyline with a constant width. This option will override the following one for poly- lines that match both categories (see below). Together with a thickness and the respective option set this will will result in a kind of a quadrilateral worm.
Closed 2d-polys as POLYGONs: 2d-polylines with the closed flag set in their header entity will appear as a polygon of the shape of the polyline. polylines with a width will not follow this rule if the previous option is chosen as well (see above). Together with a thickness and the respective option set this will result in a prismatic volume of the shape of the polyline. This option is off by default.
Faces of 3D-MESHEs: The Faces of 3d-polygon meshes will appear as a set of polygons ignoring spline fits of any kind. Nonplanar faces will be split into two triangles.
Faces of POLYFACEs: The faces of polyface meshes (from Autocad version 11 on) will appear as a set of polygons. Nonplanar faces will be split into two triangles. This option has no effect in environments older than Autocad 11.
Points as SPHEREs or BUBBLEs: Point entities will appear as spheres or bubbles depending on either their thickness (if any) or else on the value of the Autocad system variable "PDSIZE". if the result is zero the entity is ignored. This option is off by default.

Filename prefix

The names of all output files (excluding the makefile) will start with the string entered here. Default is the name of the drawing file. The tilde "~" in a path name will be substituted for the home directory ("$HOME" if present).

OK/Cancel buttons

The OK button starts the exporting after you have selected the entities you wish to extract. The Cancel button discards all the setting you have made and terminates the program. In the text dialog mode you can press -C to exit any time.

DETAILS

Torad.lsp is optimized for speed and memory usage as far as possible without losing the functionality of sorting entities to seperate files. Therefore just the entity names are stored for sorting and geometry is ignored until later. The drawback is that entity data has to be extracted twice, once for sorting and once for writing (and maybe even more for nested blocks).

The geometrical transformations are executed in one pass out of an unlimited number of nested blocks as long as no multiple inserts are involved.

DIAGNOSTICS

Error messages and alert boxes are meant to be self explanatory.

ENVIRONMENT

Autolisp variables of global scope

*exportnsegs*: Number of segments per circle for arcs [int].
*exportsmode*: Sampling mode ["Color"|"Layer"|"Toplayer"].
*exporttruelays*: Currently visible layers [list].
*exportentlist*: Currently sorted entities [assoc.list].
*exportblocklist*: Currently sorted blocks [assoc.list].
*valuablepolylist*: Currently writeable entity types [list_of_strings].
*col*: Color number used for graphical debugging [int].
*toraddlgpos*: Last position of the dialog box ['(intx, inty)].
*toradfilelist*: List of filetypes and values to write [assoc.list].
*toradetypes*: List of possible types and text entry prompts.
*toradtypelist*: Default list of entity types [list_of_strings].
*torad_error*: Exception handler [function].
*torad_preverr*: Old exception handler for reinstalling [function].
*FILE*: Current open file [filedesc].
$REASON: Control variable for dialog box (in fact local).
BD4A: Function defined by Autolisp for compiler support.

Operating system environment

HOME: Home directory used for tilde replacement.
ACAD: List of directories where Autocad looks for

FILES

Program files

torad.lsp: Main program source file.
esample.lsp: Entities sampling and conversion source file.
vector.lsp: Geometrical utilities source file.
torad.dcl: Dialog box definition file for Autocad 12.
torad.mnu/x: Menu file for setup with Autocad 10/11.

Additional Files

torad.man: This File.
torad.README: general info.

Data files

<prefix>l_<layername>.rad: Geometry data written with the Layer or Toplayer samplemodes set.
<prefix>c_<colornumber>.rad: Geometry data written with the Color samplemode set.
<prefix>.rad: Control file organizing the various data together for a complete RADIANCE scene description.
<prefix>.mat: Material definitions (all same) for manual editing.
<prefix>.view: View file.
<prefix>.sun: Daylight source definitions.
makefile: Rule definitions for the UNIX utility make.

REQUIREMENTS

Torad.lsp is meant to run with most versions of Autocad on any hardware Autocad runs on. Naturally, polyface meshes will not be extracted from version earlier than 11 drawings since they simply don't exist there. The dialog box control is unique to version 12 up to now. With other versions the setup is done by text input and the screen menu.

CAVEATS

Since torad.lsp uses layernames to form filenames in "Layer" or "Toplayer" mode when running on a PC under DOS you will have to choose your layernames very carefully and/or even enter a null string for the filename prefix. If the resulting filename is longer than 8 characters (that is the layername is longer than 5 [!] characters) torad.lsp will refuse to open the corresponding file.

Please note that the AME solid modelling package by Autodesk generates surfaces with surface normals pointing to the inside of the created volumes (at least most of the times...).

Models created with the AME Solid modelling package must have surfaces defined with the command "SOLMESH". Otherwise they consist of only wireframe information wich cannot be extracted by torad.lsp.

The "SOLID" entities in Autocad, which can be extracted with the "Extruded and flat Solids" option, have nothing to do with solid modelling or AME. These are a feature out of the 2D days of Autocad and are just flat quadrilateral faces which appear solidly filled when viewed from top. They form quadrilateral prisms if extruded, which can only be done vertically to their ground plane.

BUGS

There is no support yet for creating instances out of uniformly scaled blocks (RADIANCE does not support non-uniform scaling anyway).

The method of assigning just one standard material to all surfaces is rather primitive. It would be nice to have access to a library of predefined material types or at least to extract rgb-values out of the Autocad color numbers.

Cylinders (circles with a thickness) within a scaled block are output with unscaled diameter.

AUTHOR

Georg Mischler

ACKNOWLEDGEMENTS

Final development of this program has been sponsored by Prof. Dr. B. Keller, Building Physics, Dept. of Architecture ETH Zurich.

The development environment has been provided by Prof. Dr. G. Schmitt, Architecture & CAAD ETH Zurich.

LEGALESE

        Copyright © 1993 Georg Mischler / Lehrstuhl für Bauphysik,  ETHZ
 
        Permission to use,  copy,  modify,  and distribute this software
        for any purpose and without fee is hereby granted, provided that
        the above  copyright  notice appears in all copies and that both
        that  copyright notice and this  permission notice appear in all
        supporting documentation.
 
        THIS  SOFTWARE  IS PROVIDED  "AS IS"  WITHOUT EXPRESS OR IMPLIED
        WARRANTY.  ALL IMPLIED  WARRANTIES OF FITNESS FOR ANY PARTICULAR
        PURPOSE AND OF MERCHANTABILITY ARE HEREBY DISCLAIMED.

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