Corona sun

[flysimon]

I'm wondering is it possible to change the shape of the corona sun to a custom shape? Or if possible mask apply a mask to it

[maru]

I am really curious why you would want to do that.

[TomG]

Curiosity x 2!

[dj_buckley]

To simulate clouds/softer sun maybe, in a more irregular way than just increasing the size of the sun?

[flysimon]

I just thought it would be cool to experiment with the sun and see what type of results it can produce, also for artistic purposes.

[romullus]

I could be wrong, but i think it's doesn't matter what shape of the sun would be, you would not see a difference because of its apparent size, i.e. it's so small that from the shadows it's casting, you could not tell if its shape is triangle, donut, or dancing unicorn.

[mferster]

Incorrect! you can use big objects far out in your scene that can obscure and change the shape of your sun and effect the bokeh effects created from the sun.
 
I used a giant sphere to simulate an lunar eclipse and then went wild and made a star shaped hole cut out of a circular plane to get star shapes.

[TomG]

But where's the dancing unicorn one? Inquiring minds want to see the result! :)

[romullus]

I stand corrected. I totally forgot about those amazing solar eclipse shadows. Now if only the moon had the shape of an unicorn :]

[mferster]

Geeeezzzz so demanding! Hard to see but they do have horns!

[romullus]

I used a giant sphere to simulate an lunar eclipse and then went wild and made a star shaped hole cut out of a circular plane to get star shapes.

Wait a minute! That's not the same as changing the shape of the light source. You introduced aperture in light's path and it changed the shadows. Shape of light source has nothing to do with that (as long as we're talking about the sun). Remove the aperture and change light's shape and you probably won't see any difference compared to the ordinary sun.

[TomG]

However it was done..... yay dancing unicorns! ;)

[Juraj]

I used a giant sphere to simulate an lunar eclipse and then went wild and made a star shaped hole cut out of a circular plane to get star shapes.

Wait a minute! That's not the same as changing the shape of the light source. You introduced aperture in light's path and it changed the shadows. Shape of light source has nothing to do with that (as long as we're talking about the sun). Remove the aperture and change light's shape and you probably won't see any difference compared to the ordinary sun.

Yeah this, like Romullus says.

I actually did some "research" (quick experiment) to see if sun could be altered in way that it produced dappled shadows directly by itself identical to effect from occluding tree branches. All in single mapped 360 Dome HDRi.
And no, the object has to stand between the light source and object on which light is being casted.

It's possible to do some funky stuff with the sun shape but the effect isn't enough by itself. The occluding needs to happen on different plane of distance.

[mferster]

Wait a minute! That's not the same as changing the shape of the light source. You introduced aperture in light's path and it changed the shadows. Shape of light source has nothing to do with that (as long as we're talking about the sun). Remove the aperture and change light's shape and you probably won't see any difference compared to the ordinary sun.

Hmmmm looks like it still works the same way. I made a "mickey mouse" sun by combining 3 suns touching each other and all oriented pointing at the same spot, with no shaped aperature between them and the tree leaves and it makes a similar effect.

[romullus]

Hmm, then maybe the gaps in the leaves is an actual aperture and position of the moon is not important. Ok, i admit that i have way to little knowledge to judge this, therefore i must apologise you for wasting your time.

Edit, but your experiments are interesting and i believe they will be valuable for someone.