Editing User:Xuwei/DevLog2019

=Coummunity Bonding Period=
* Set up the Development log
* Set up the development environment such as OS.
* Start to look at the different potential libraries code base.
* Discuss with mentors which external library to choose.

==May 16th==
*Start to check the checklist.
**Agreement sent.
**Dev log created.
**My Profile created.

==May 17th==
* Had four of my wisdom teeth extracted. The progress for the following week may be slow due to teeth extraction.

==May 19th==
* Looking at [https://bitbucket.org/Coin3D/dime/src/default/ Coin3D/Dime] code base, a possible library for DXF import/export.
** It has no external dependency.
** It supports all past and should support the future version of DXF format.
** It compiles on Windows, Linux, MacOS, etc.
** But it only loads DXF files into Dime object hierarchies and saves Dime object hierarchies as files conforming to DXF format.
** Seems only support 3D.

==May 20th==
*Looking at [https://sourceforge.net/p/brlcad/code/HEAD/tree/brlcad/trunk/src/conv/dxf/ BRL-CAD] DXF import/export code. Trying to understand how it works and see if it is suitable for OpenSCAD.
**It converts DXF format to .g and .g to DXF which is a BRL-CAD format.
**It seems that BRL-CAD does not support the entire format, only the part that is relative to solid-model.

==May 21st==
*Looking at [https://qcad.org/en/90-dxflib dxflib] which is used by QCAD and works fine, but it only supports 2D which is not ideal since OpenSCAD is already supporting 2D.
**Maybe we can add the 3D part. But not sure how hard it is to add that.

==May 22nd==
*Searching for a library that supports both 3D and 2D DXF import/export.
**Libraries above are for either 2D or 3D.
**Found some libraries support both but they are written in python instead of C++.

==May 23rd==
*Continue on searching for the potential library.

==May 24th==
*Looking at and Compile [https://github.com/LibreCAD/libdxfrw libdxfrw] code base which is used by LibreCAD.
*Will be out of town for the next two days.

=Coding Period=
==May==
===May 27th===
*Looking at both libdxfrw(libdxfrw.h, dxfreader.cpp) and OpenSCAD(dxfdata.cc, dxfdim.cc, import.cc) relative code.
**Comparing the differences between these two on how they handle DXF data.
**Trying to form a connection between these two.
**dxfdata.cc seems a bit complicated. Need some time to digest.
**The way that libdxfrw reads DXF file is kind of mixing with DRW code.
**libdxfrw encounters problems when dealing with elevated arcs(no response yet).[https://sourceforge.net/p/librecad/bugs/596/]
*Looking at dxflib code base as well.
**dxflib does not store any entities, only pass supported entities.
**A useful link for understanding dxflib data structure.[https://qcad.org/doc/dxflib/2.5/classref/class_d_l___dxf.html]
===May 28th===
*Move on to reading dxflib code for now
**Continue reading the link about the data structure of dxflib above.
**Trying to understand form the connection between dxflib and OpenSCAD code base.
*Continue reading dxfdata.cc
===May 29th===
*Found another one existing integration with dxflib that I can use it as reference.[https://github.com/CauldronDevelopmentLLC/CAMotics/tree/master/src CAMotics]
*Continue on reading dxflib and import.cc, dxfdata.cc.
**Keep trying to write some code that may help understanding how to integrate the library.
*Fill out the comparison [https://github.com/openscad/openscad/wiki/DXF-Library-overview wiki page]

===May 30th===
*Had to go the dentist this morning, will catch up the afternoon and at night.
*Keep browsing for more information for those four libraries.
*Reading [https://images.autodesk.com/adsk/files/autocad_2012_pdf_dxf-reference_enu.pdf DXF standard] to learn how DXF format works

===May 31th===
*Searching more information for potential libraries.
**Add more information that found to the comparison page.
*Learning how to integrate the library from the [https://ribbonsoft.com/doc/dxflib/2.5/reference/contents.html instruction] written by QCAD.

==June==

===June 3rd===
*We stick with using BRL-CAD's code for now.
*Try to implement the circle entity.
**Add a callback function on [https://github.com/leonplust/brlcadDXF/commit/1abc40cbe24793fbd9f94001b1a8d30e28602780#diff-3db848059130b96c98744620379df21a dxf-g.c] to pass the data back to openSCAD.
**Add processentitiyecircle() to [https://github.com/leonplust/openscad/blob/dxflibrary/src/dxfdata.cc dxfdata.cc] and some other changes to enable that function.
**Having some issue with ADDLINE. Will dig into that later.

===June 4th===
*Push few commits on [https://github.com/leonplust/openscad/tree/dxf-import import_dxf branch].
**Basically create a new import_dxf() function that replace the old dxfdata.cc
**Implement a simple geometry to test out the function

===June 5th===
*Modify the code committed yesterday to output a simple circle.
*Trying to understand layer, block.

===June 6th===
*Created a new branch [https://github.com/leonplust/brlcadDXF/tree/prototype prototype] on brlcadDXF repo.
**Trying to clean up the code so that it could compile independently.

===June 7th===
*Switch some functions and datatype and continue on cleaning up the code.
*Spend most of my day studying the exam tonight. Will make up the time tomorrow.

===June 8th===
*Walked through the whole file line by line and cleaned up as much as I can so far. There are still many details that I need to learn to clean up the rest.

===June 10th===
*Made changes to dxf-g.c according to the answer from brlcad.

===June 11th===
*fix bu_list with std::list and related functions, etc.

===June 12th===
*Add functions for circle eclipse from vmath.h, color.h.

===June 13th===
*Added more functions from dependencies.
*uploaded a file that records to-do list, question, notes, etc.
===June 14th===
*few fixes on dxf-g.cc.
*Study for the midterm tonight for the most of the day will make up the hours tomorrow.

===June 15th===
*Finished converting all bu_list data structure to std::list except in one function drawmtext().
**drawmtext() may be removed later.
===June 17th===
*Finished fixing all bu_vert_tree structure.
*Started on fixing vls a bit.
===June 18th===
*Finished fixing all vls except those in the main().
===June 19th===
*Finished most of the parts of dxf-g.c.
** Create a new branch [https://github.com/leonplust/brlcadDXF/tree/test test] for testing and commented out some less necessary functions to test.
** Upload test files from openSCAD testdata/dxf
** Need to fix the segmentation fault.

===June 20th===
*Fixed numbers of segmentation faults mainly caused by malloc.

===June 21st===
*Fix strncmp function error
*Tested with circle, ellipse, failed at block section.
*Tried to reconstruct block_list, block_head data structure.

===June 24th===
* Fix block_list data structure
* Now dxf-g.cc can go through the whole dxf file and spit out data to file output
* Done basic testing with circle, ellipse, polygons, lwpolyline. files from openscad testdata/dxf.
** Found the correct geometry.
** coordinates of the vertices are correct.

===June 25th===
* Randomly picking files from openscad/testdata/dxf to check geometry and coordinates.
* Trying to figure out if the data structure is actually storing the correct data.

===June 26th===
* Trying to extract data from the data structure to test if it's reading correct data.
** For circle, extract cirlce_pts.
** For line, extract line_pts.
** For lwpolyline, extract polyline_vertice.
** For elllipse, center and majorAxis
** For point, pt.

===June 27th===
* More data extracting continue from yesterday.
* Try to start integrating openscad and dxf-g.cc just for circle entities.

===June 28th===
* Run openscad together with dxf-g.cc.
* Implemented circle entities using dxf-g.cc called a openscad function.
** Later the day discussion concluded that this is not the preferred way. deprecated.

==July==
===July 1st===
* Added structs for each geometry for storing the data.
* Some minor fixes for original data type point_t.
===July 2nd===
* storing all the data parsed to the respect vectors.
** Except polyline is a bit tricky, not done yet.

===July 3rd===
* Added polyline struct and the storing part.
* Added code for passing circle entity information to openscad and openscad draw it.
** Having trouble with compilation.

===July 4th===
* Added arc, line, points, lwpolyline.
** Still have some problems with lwpolyline.
===July 5th===
* fix lwpolyline.
* Added ellipse.
* Found problem with mesh.

===July 8th===
* Trying to fix mesh

===July 9th===
* Change the structure of the entire code to use the code of dxfdata to fix the mesh problem
* The code still not able to produce the correct polygon yet.
===July 10th===
* Fix the mesh problem and now the code can properly import a single dxf file.
** For some reason, the data is store and fill in the next polygon if the second dxf is imported.

===July 11th===
* Fix the data leakage between document.
* Now the code is passing all the test file except nothing decimal comma and transform insert.
** the reader has an issue with insert entity

===July 12th===
* Trying to figure out how to fix the insert.
* Learning the insert spec from dxf manual

===July 15th===
* Fix the block list and curr_block is not storing value properly
* There is an infinity loop caused by the file offset in the process_enitites_unknown
** It jumps to the preivous line but does not jump back
* Continue on fixing insert

===July 16th===
* Clean up most of the commented code in dxf.cc and dxf.h
* fix the curr_block memory issue by using a global variable indx that indicate the position of the block in block_list
* Continue on fixing insert

===July 17th===
* Adding back_file_offset to state_data to have the program jump back
** Still getting the wrong result, the geometries are scattered but shapes are the same.
* Continue on fixing insert

===July 18th===
* replace all memory allocation function related to insert with new and delete
** valgrind now output no error or warning
* Continue on fixing insert

===July 19th===
* Download and build brlcad to test out what's the difference and if it can output the correct result
** There is no problem with the curr_state->file_offset
* Continue on fixing insert

===July 20th===
* Found that the brlcad xform is different than my version. 
** Can't figure out why it's different
* Continue on fixing insert

===July 21th===
* Found the BU_LIST_POP actually assign curr_state to the last element of the list
** This fix the infinity loop and remove back_file_offset.
* Continue on fixing insert

===July 22th===
*By switching the push_back and new_state = curr_state this fix the xform problem.
** Insert is fixed but it looks there is an issue with different compiler