Le 2024-04-13 à 15:07, RATH, CHRISTOPHER A a écrit :
> On 4/13/2024 2:55 PM, Cousin Ricky wrote:
>> "RATH, CHRISTOPHER A" <car### [at] comcastnet> wrote:
>>> This is a work-in-progress inspired by a photo I took of my grandson
>>> chasing soap bubbles in his yard.  As usual, it was supposed to be a
>>> brief doodle, but has morphed beyond that.  I have started adding other
>>> things that "float" in various ways to model in the scene as well.
>>
>> Are those floating objects intended to be bubbles?  They look like 
>> solid water
>> droplets.  Hollow bubbles do not invert the scene behind them.
>>
>> The cracks in the pink granite blocks are conspicuously regular, but 
>> I'm sure
>> you already have plans for those.
>>
>>
>>
> Yes, the are supposed to be bubbles.  I'm not sure what I'm doing wrong 
> yet, but I have noticed that effect.  They are isosurface shells with 
> very thin walls.  The material has an ior of 1.33, which is wrong and is 
> probably causing the issue.  I guess a soap bubble has an ior pretty 
> close to 1, so I'll have to play with that.  I think when I was trying 
> to get the irrid right I pushed the ior back up, but got that side-effect.
> 
> The balloon isn't quite right either.  It's too glossy so it looks more 
> like glass.
> 
> I think the cracks need to line up with the cracks in the foundation as 
> well.  More things to play with.
Check with your isosurface that it actually have an inner opening. 
Render just a single one cut in half using a difference or intersection.
Assuming that Bubble_Object is defined at the origin and having it's own 
texture :
difference{
	Bubble_Object
	box{<100, 100, 0><-100, -100, -100> pigment<1,0,0>}
   }
or
intersection{
	Bubble_Object
	box{<100, 100, 0><-100, -100, 100> pigment<1,0,0>}
   }
You need to see only a thin line of red around the shape. If the whole 
surface is red, then, it's not hollowed out properly.

The ior is correct. Bubbles are mostly water, and water's ior is 1.33.
The best/easiest way to model those is the difference of two spheres.
difference{
	sphere{Centre, Radius}
	sphere{Centre, Radius-0.001}
	pigment{rgbt 1}
	finish{reflection 1 specular 1 fresnel irid Value}
	interior{ ior 1.33 }
   }

The balloon need to have some blurring in the reflection. Probably also 
need to reduce the amount of reflection.

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