Addition of external shadows

Hi all,

Here is a new proposal for the sim_physics branch: like the MLS one, this means that this is successfully implemented but awaiting some code cleaning/UI modification from experienced blender dev like Matt Ebb: As he kindly helps me in his free time and because he has a lot to do, please understand that it can take more time than expected…

In the current time, there are still plenty of gifts from the generous Matt Ebb to test: do not hesitate to ask questions about the sim_physics on my blog: even if I am not always connected, a friend of mine has told me that he would help as much as possible those who are already lost…

Proposal for sim_physics: Adding external shadow support

Adding full shadows greatly enhance realism and directly allows spectacular VFX such as the alien Suzanator vessel darkening part of the cloudy sky 😉 (Fig. 2)

Matt Ebb had previously implemented shadowing derived from the very design of the raycaster engine:  objects inside a volumetrics cast the light. However objects outside the volumetrics did not occlude light sources, leading to unrealistic illumination. I have so corrected this issue: now let the pictures speak as usual 🙂


Fig. 1 – current sim_physics branch – render time: 9 s


Fig. 2 – external shadows support – 20 s

You can see on the 3 images just below that this leads to the expected illuminations.




Full volumetric shadows calculation can be a very time consuming process by increasing up to twice the render time. Consequently, since it is not always needed, the user should have activate/deactivate it in a panel (no other UI button is needed)


Fig. 3 a), b) – no external shadows


Fig. 4 a), b) – external shadows


Fig. 5 – external shadows with more lamp samples

The calculation also takes into account self-shadowing


External shadows are very important for increasing the relationship between the volumetrics and the rest of the scene through light interactions. High render time could easily be decreased in the future by storing the shadows in the Light Cache structure (work-in-progress)

Cheers to all, Raúl Fernández Hernández

Addition of external shadows

6 thoughts on “Addition of external shadows

  1. David says:

    Excellent work! Another great toy to look froward to playing with.
    sim_physics branch problem. It seems that the last svn merge, -r 17502:18705 by genscher, has made it so that it will not compile with scons + mingw on win32. (will double check when I get a chance.)


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