[SoC] GSoC 2020 - Coding Period Week 5 Report

[BELGACEM NEDJIMA]

Hi all,
During the fifth week of the summer of code I made a lot of progress
implementing the 3D scenes export feature. Here is my report for the week:


   -
   - Tasks done:
      - Got exporting the vector layer data working.
      - Saw how the flat terrain is generated and how the level of details
      system works.
      - Exported visible terrain tiles by taking the Qt3DRender::QAttribute
      objects directly and parsing the data.
      - Exported invisible terrain tiles by generating geometries manually.
      - Exported DEM terrain tiles (I had some troubles with non square
      height maps giving me wrong values but I eventually fixed the problem).
      - Discovered smooth edges parameter in the wavefront .obj standard
      and implemented it (I'm following this very useful spec obj-spec
      <http://fegemo.github.io/cefet-cg/attachments/obj-spec.pdf>)
      - Gave the user the ability to choose at which level of details he
      wants to export.
      - Made initial UI and classes for the scene export settings.
      - Switched from the user specifying the level of details to
      specifying the resolution of the terrain (more predictable in terms of
      loading speed and vertex count).
      - Made a separate class named Qgs3DExportObject that will handle the
      object name and various 3D data (to handle absence of texture coordinates
      data in a better way in the future).
      - Gave each object in the scene it's own object name in the .obj file
      so that blender users can edit the scene in a better way.
      - Documented the code and made a draft pull request that you can find
      here: https://github.com/qgis/QGIS/pull/37588
      - Discussed what I implemented with mentors.
   - Screenshots:
      - DEM terrain inside QGIS: https://imgur.com/aZl0E03
      - Exported DEM terrain (smoothing option to the left):
      https://imgur.com/Jkl9kfu
      - Exported vector layer with a flat terrain: https://imgur.com/LWBtHqf
   - Tasks to be done:
      - Export other types of layers (mesh layers, 3D symbol layers...).
      - Handle exporting of normals.
      - Handle exporting of texture coordinates.
      - Export textures as displayed in the scene to an image file.
      - Manage material file (.mtl) construction.
   - Blocking issues: Not really a blocking issue but I wanted to do export
      scene hierarchy in the .obj file but that didn't seem to work in
blender :(.

Any suggestion or feedback is always welcome.
Best wishes,

-- 
Belgacem Nedjima
4th year computer science and engineering student.
https://github.com/NEDJIMAbelgacem
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