Understanding Blender source code

In order to implement the changes into the Blender and cycles source code needed to achieve the logic for my bachelors thesis I am on a continuing journey to understand said source code.

Especially the code that is responsible for viewport rendering and the code for object transformation are relevant for the project.

What I could learn so far:

Main Window Loop

• creator.c : Blender main function ->
• wm.c(WindowManager) : WM_main Main program loop ->
• wm_draw : wm_draw_update update all non minimized windows, (swap_buffers) ->
• wm_draw : draw_window ->
• wm_draw : draw_window_offscreen ->
• area.c : ED_region_do_draw draw region
• …

Viewport Render with Cycles

The logic for viewport rendering seems to be independant of the main window loop and gets triggered whenever a view gets updated by any sort of event. A click in a viewport suffices for example.

• draw_manager.c : DRW_draw_view ->
• draw_manager.c : DRW_draw_render_loop_ex (render Loop for external render engines?) ->
• draw_manager.c : drw_engines_init ->
• external_engine.c : external_engine_init (Cycles is an external render engine?) ->
• draw_manager.c : drw_engines_draw_scene ->
• external_engine.c : external_draw_scene ->
• external_engine.c : external_draw_scene_do ->

• Some RNA related classes I wasn’t able to wrap my head around yet

  eventually we end up at the Cycles code:

• blender_session.cpp : draw (draw call in cycles with width and height parameters. Are these the measures of the view?)

I wasn’t able to identify the exact point where Blender code calls Cycles code. This is my main priority right now and I have started a thread on Blender stack exchange.

Transform Logic

The documentation on the Blender wiki is informative, but not completely up to date. The main API, described in transform.h is located in source/blender/transform not in “source/blender/include/BIF_transform.h” as far as I could tell. I wasn’t able to identify the parts of the code which are responsible for updating the view after a transformation has taken place. This is another priority at the moment.

Notes

the Blender source code seems to be written in plain C for the most part, while Cycles was implemented in C++.