Amiga Plus 2000 #1/Amiga Plus CD - 2000 - No. 1.iso/Tools/Dev/Meshwriter_lib/Library/meshwriter.readme

Text File | 1999-12-03 | 12KB | 490 lines

                        MeshWriter.readme


                          Version 0.2




28. march 1999                                 by Stephan Bielmann



Table of Contents
-----------------

 1.     Licence

 2.     Overview

 3.     Requirements

 4.     Installation

 5.     Conventions

 6.     Function overview

 7.     Supported formats

 8.     Sample source and programs

 9.     Known problems.

 10.    Future




   Stephan Bielmann
   Im Dorf 2
   1718 Rechthalten
   Switzerland

   [e-mail]
   http://www.rega-sense.ch/~sbielmann/amiga/index.html





1. Licence
---------


The library and files in this distribution are freely distributable
under the restrictions stated below, but are also copyright (c) to
Stephan Bielmann.

The library is FREEWARE. Feel free to distribute it on any media as
long as the content of this archive rests unchanged and complete.

By using this library in your program, FREEWARE/SHAREWARE/COMERCIAL,
you may only include the library itself and a copy of the README file,
instead of the whole archive. And because its FREEWARE you dont have
to pay me something for it. Nothing against gifts :)

But you have to do the 3 points listed below :

1: Adding a string like "Using meshwriter.library Copyright by Stephan Bielmann"
   to your about or information window/text.

2: Adding a similar remark in the documentation of your program with the URL
   of my meshwriter homepage and e-mail of me.

3: Just drop me a mail to inform me that you wrote a program which uses
   my library and for which purpose it is.

Payment for this archive or parts of its content is only permitted
to pay the media on which it resists itself.

Everything in this distribution must be kept together, in original
and unmodified form.


THE LIBRARY IS PROVIDED TO YOU "AS IS," WITHOUT WARRANTY. THE ENTIRE
RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD
THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY
SERVICING, REPAIR OR CORRECTION.




2. Overview
-----------


The library its goal is like the name says : to write meshes.
And which has to be written this way that future releases, with
more output formats can be used directly without to recompile
programs who use it.


Whats a mesh ? A 3 dimensional polygon object, which consists of vertices,
each vertex is described by his position in the space along the x,y and z-axis.

Vertices can be put together by creating polygons which contain those vertices, or
triangles, anyway : ALL IS THREATED LIKE A POLYGON.

Vertices with same coordinates are stored one time only to gain memory.

Further a mesh can have a name, which has nothing to do whith its file name, but
this one is used to identify it inside the prefered 3d tool of the user.

A copyright string, for developers :-), if they mean that people have to
know which great program made this mesh.

Camera information and a single light source is not really mesh related but
in some cases used for a correct output, like POV.

Each polygon may have a surface information, a material. Materials have an
ambient color (rgb), a shininess and a transparency information.

Like OpenGL a current transformation matrix is used to transform each
vertex when you add it. So you can perform translations, rotations and
change the scale of your vertices.

The way of use it is in all cases the same, and that the real fun!

Make a program which uses the library, for automatic or paramterizable
shape creation or even modelization with output or export functionality.

The library can handle multiple meshes at the same time, all depends on
the amount of memory of the used system.

Once you think you added all your polygons, materials and so on let
it display a save requester to the user, or do this at the beginning,
to let him choice the output format.

Need to save it in multiple formats, just save it again, and again :-)
by changing the output type.

Forgot something ? Just add it to the mesh and save it again.

Or if you want to write a program which can explicitly make only
output of one or a few formats simple tell this to the library.




3. Requirements
---------------


The library needs the utility.library V37 to parse TagItems and was
programmed according the rules of the libraries V3.0.




4. Installation
---------------


Just put a copy of the library into your libs: directory.

The include files for developers should be copied into your
developing environment.




5. Conventions
--------------


That things happens as they should, I had to define some conventions.

 -The coordinatesystem

        +Z
         |    -Y
         |   /
         |  /
         | /
  -X____ |/____+X
        /|
       / |
      /  |
     /   |
   +Y    |
        -Z

  X from left to the right.
  Y from behind to the front.
  Z from the bottom to top.

  It is a right-handed coordinate system.

 -Polygons and triangles

  As mentioned before a triangle is nothing else than a polygon
  with 3 vertices.

  Only convex polygons are supported. Others wont be saved
  correct.

  All vertices have to be drawn counterclockwise! This is
  for two reasons. The library itselfs need a possibility
  to recognize hidden surfaces, and by the way all output
  formats too.

 -Materials

  Colors are built with red, green and blue components from
  0 up to 255.

  Values like shininess and transparency are made from 0.0 to 1.0.

 Remark

 The library makes all needed conversion internally, as for example
 for Lightwave objects which axis are defined the other way, and  polygons
 clockwise.



6. Function overview
--------------------


For real documentation look at the autodoc. This is just to
give you an idea of the functionset.

Each function begins with MWL for MeshWriterLibrary.

The name itself gives already a good idea what the function
will to at least. Like MWL2DFileFormatExtensionGet.

2D
File
Format
Extension
Get

Got it ? Easier that SQL ...


Functions can be separated in different sub groups :

 2D functions

  MWL2DFileFormatExtensionGet
  MWL2DFileFormatIDGet
  MWL2DFileFormatNamesGet
  MWL2DFileFormatNumberOfGet

 3D functions

  MWL3DFileFormatExtensionGet
  MWL3DFileFormatIDGet
  MWL3DFileFormatNamesGet
  MWL3DFileFormatNumberOfGet

 Drawing mode functions

  MWLDrawModeIDGet
  MWLDrawModeNamesGet
  MWLDrawModeNumberOfGet

 Mesh manipulation functions

  MWLMeshCameraLightDefaultSet
  MWLMeshCameraLookAtGet
  MWLMeshCameraLookAtSet
  MWLMeshCameraPositionGet
  MWLMeshCameraPositionSet
  MWLMeshCopyrightGet
  MWLMeshCopyrightSet
  MWLMeshCTMReset
  MWLMeshDelete
  MWLMeshLightColorGet
  MWLMeshLightColorSet
  MWLMeshLightPositionGet
  MWLMeshLightPositionSet
  MWLMeshMaterialAdd
  MWLMeshMaterialAmbientColorGet
  MWLMeshMaterialAmbientColorSet
  MWLMeshMaterialDiffuseColorGet
  MWLMeshMaterialDiffuseColorSet
  MWLMeshMaterialNameGet
  MWLMeshMaterialNameSet
  MWLMeshMaterialShininessGet
  MWLMeshMaterialShininessSet
  MWLMeshMaterialTransparencyGet
  MWLMeshMaterialTransparencySet
  MWLMeshNameGet
  MWLMeshNameSet
  MWLMeshNew
  MWLMeshNumberOfMaterialsGet
  MWLMeshNumberOfPolygonsGet
  MWLMeshNumberOfVerticesGet
  MWLMeshPolygonAdd
  MWLMeshPolygonMaterialSet
  MWLMeshPolygonVertexAdd
  MWLMeshPolygonVertexAssign
  MWLMeshRotationChange
  MWLMeshRotationGet
  MWLMeshSave2D
  MWLMeshSave3D
  MWLMeshScaleChange
  MWLMeshScaleGet
  MWLMeshTranslationChange
  MWLMeshTranslationGet
  MWLMeshTriangleAdd
  MWLMeshVertexAdd

2d,3d and drawing mode functions can be used at every moment.
To setup your program, if it runs under CLI or in a preferences
window. Or at least before you save the mesh. With these functions
you will in fact define the type of output.

Mesh manipulation can be made after creation of a new mesh
MWLMeshNew until you drop it with MWLMeshDelete.


Almost all functions are made as Get/Set pair, because values
can be set by default and for interaction reasons.




7. Supported formats
--------------------


 Here a list of all supported output formats and what properties
 of the library they get, or better how they are interpreting them.

 Formats which have to convert the polygons to triangles can be
 lossy !! But only if you forgot to make polygons with at least
 three vertices ;-)

 Always the ID, the name or description of the format and its extension
 followed by the explanation.


 3D formats
 ==========

  T3DFRAWA   RAW ASCII            raw

   ASCII file which contains the name of the mesh on the
   first line. Followed by triangles printed as sets of 6 floating
   point values separated by a space.


  T3DFRAWB   RAW binary           raw

   Binary representation of the above one. Name which is 0
   terminated and then triangles as sets of 6 points, each point is
   a 4 byte floating point value.


  T3DFDXF    AutoCAD DXF          dxf

   ASCII output which contains a layer per materials and
   interprets only the color information.

   The polygons are made with POLYLINE entities.

   Name and copyright are written.


  T3DFVRML1  VRML 1               wrl

   ASCII file, which reflects the mesh as it is, with polygons
   and materials indexed on each polygon.

   Name and copyright are written.


  T3DFPOV3   POVRay 3.X           pov

   ASCII file with standart light source and camera to be able
   to render the file and to get a correct view of it.

   Polygons saved as triangles and materials indexed to each triangle.

   Name and copyright are written.


  T3DFLWOB   Lightwave            lwob

   Binary polygon represantation with full material support indexed
   to each polygon.


  T3DFTDDD   Imagine original     iob

   Binary triangle represantation. Material indexed per triangle but
   without the shininess.

   18 characters of the name are written.

  T3DFTDDDH  Imagine huge         iob

   Binary, as above, but can store bigger objects. Supported on Amiga
   since version 3.0 of Imagine.


  T3DFREF4   Reflections 4.X      r4

   Binary triangle representation with materials indexed per triangle.

   Name is written.

   Recently renamed to monzoom or similar.


  T3DFGEOA   VideoScape           geo

   Ascii polygon represantation with material information per polygon.

   Currently only the 16 default matte cololrs are built in.


 2D formats
 ==========

 In work.


8. Sample source an programs
----------------------------

 For the moment not a lot, but suffisent to show you what the
 library is made for.

 The TestMeshWriterLib calls each function, creates 3 polygons
 and writes them down on RAM: in each format, 3d and 2d.

 MeshWriter is a simple MUI program for tests supposed it was
 written by using MUIBuilder by Eric Totel.

 Based on Stephan Bodmer his Geo2Vrml I wrote geo2any to give a
 example of how to use the new functions for convertions. Source
 is included. Thanks to Stephan for his help.


9. Known problems
-----------------

 Very strange things are happening when computing the circle, as
 delivered as sample, and save it as an Imagine object. Imagine
 tells that it finds a bad chunk size.. however, I did not find
 it.

 The camera settings for the POV format is still not the best
 one, which is in case the internal camera which is used for
 PostScript and VRML too.

 Some applications have problems when reading GEO files with
 exponential value represantation.

 As I dont earn, like nobody else :), a correct documentation of
 the Videoscape GEO format, some cases are not treated or
 produce even errors.

 Seems that Reflections 4 does not handle my DXF output as it
 should, other applications do it correct.
 However, save it as Reflections and forget this one :)

10. Future
---------

 Still not implemented are :

 -What about a better documentation, it will be HTML only, soon !
 -PostScript support in the 2D ouput section has still some problems
  wait for 0.3.
 -Cinema4D,Aladdin4D,Real3D,Tornado3D,RayStorm,Studio3D,
  and VideoScape binary as soon as I get the floating point
  format descriptions.
 -More background about the formats in the documentation.
 -Source code savers, like GL for CyberGL, Mesa or OpenGL.
 -Some more surface/material parameters.
 -All needed overflow checks for the used output formats.