[Bf-viewport] Failled accurate soft shadow attempt

[Clément FOUCAULT]

Hi Felipe,

I am well aware of what unreal engine 4 does.

The problem with distance field is accuracy. It's great for smooth really
blurry shadows but not for very detailed sharp shadows.
There is a lot to consider when using SDF, storage is one of them. To keep
memory usage low enough, we would have to use streaming and LOD system. So
complexity is a problem.

Also as you mentioned the SDF does not works with deformable meshes. But in
Blender there is not only armature that are deformable. The whole modifier
stack can deform the mesh and therefore the shadows. For animated deformed
objects it would require recomputation every frame.

Also precomputation time is prohibitive too. There is simple methods but
only for manifolds meshes.

I wish that SDF shadows could have been the solution but it's a whole new
dimension of problems.

Thanks for pointing it out though, it's true that I did not mentioned it in
the report.

Regards,

Clément

2017-09-04 18:32 GMT+02:00 Felipe Botero <boterock at gmail.com>:

> Hello,
>
> I am no expert on the topic, but I know that in UE4 they use Distance
> Fields for blurred shadows, this has the disadvantage that meshes' distance
> fields need to be built, but it seems to solve the problem, and also allows
> them to use the distance fields for AO.
>
> Maybe having DF shadows disabled while in edit mode, but enabling them in
> object mode maybe would work, and building the distance field in the
> background if the mesh changed.
>
> Also for skeletal meshes they also have smoothed shadows, but they don't
> use mesh data but instead a PhysicsAsset data (which is basically the
> capsules or other primitives used when simulating a ragdoll), maybe in
> blender for those meshes the skeleton envelope could be used.
>
> Thank you for your time, and keep up your fantastic work!
>
> - Felipe Botero
>
>
> On Mon, Sep 4, 2017 at 8:39 AM, Clément FOUCAULT <foucault.clem at gmail.com>
> wrote:
>
>> Hi guys,
>>
>> As you may have noticed I had some trouble one week ago and did not
>> commited anything. This is because I was trying to get the most awesome
>> shadows out of shadow maps.
>>
>> Foolish of me to think this had not been attempted before. I reckon
>> having lost a bit of time before doing research.
>>
>> But long story short: There is no good, easy, fast solution for realistic
>> soft shadows. By this, I mean contact hardening soft shadows. Fixed size
>> penumbra shadows will be implemented (they already are).
>>
>> A more complete explanation of what I tried can be found here:
>> https://wiki.blender.org/index.php/User:Hypersomniac/
>> Dev_reports/Soft_shadows_failure#Soft_Shadow_Map_Faillure
>>
>> If someone is feeling more confident on this and want to take a shot at
>> it, please do and get in touch.
>>
>> Clément
>>
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>>
>
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