POV-Ray [plugin] (updated: 2016/Aug/08)

[micheus]

Sorry for make this post long, but I need show the informations I got before ask some questions. Thanks for any help/idea/comments...

It depends on whether it's specified as a point light or an area light.

Yes, and POV-Ray allow us to use "virtually" any kind of light for that object (virtually because I don't think others than these ones can be useful):
Parallel light:

Point light (the default type - set by the omission of a type of light):

Cylinder light:

Spot light:

Shadowless light:


The "area_light" term can be assigned for any kind of light - it is used exactly to produce soft shadows (compare them with the images above - see the box shadow):
Area light definition (Point light+area light ):

Spot light + area light definition:


So, Wings3d has only a menu option: "Object to Area light". Now, we know that the exporter is always creating a point light with soft shadows.
If we want to turn the object an emitter but producing sharp shadows, will we need to hack the .pov file?

That was the first aspect that drove me to make that question...

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We note that we have placed this area light in the x-y-plane instead of the x-z-plane. We also note that the actual appearance of the light bulb is not affected in any way by the light source.

... and this was the second.

After do some tests I noticed that when we use the term looks_like combined with area_light in the light definition the axis vectors (orientation) for area light doesn't matter...
Here a scene with an regular area light added to Wings3d scene:

below is the result (the small size and orientation produce shadows in the wall - compare it with that one in the previous post):


... but the size of this area is very important

The test environment:

Code:

- one Parallel light
- one sphere converted to an Area light 4x4 (1un diameter):
-> the object had two materials before being converted: half red + half blue;
-> its color was set to White.
- one sphere (1un diameter - smoothed);
- one cube (1un HxWxD).

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The bulb must be illuminated by some other light source or by, as in this case, a high ambient value...

... and that would be the third.

The object-light without Ambient influence (Ambient <0,0,0>):
In this situation, you can notice that the source of light came from the middle of the object and you also can observe the texture as it was defined because it's being illuminated by the parallel light.
By comparing these three images you can see that the shadows is growing:
a) area_light <1, 0, 0>, <0, 0, 1>, 4, 4

b) area_light <2, 0, 0>, <0, 0, 2>, 4, 4

c) area_light , 0, 0>, <0, 0, 3>, 4, 4

First question:
- How should we determine that size? Would it be by doing something like getting a bbox from the object and using its x-z plane dimension? Would it be the best option?

Now comparing the use of the ambient light property:
without ambient light influence (we see the material of the object):

with ambient light influence - huge value (we see only an light object):


Second question:
- Is there any situation where the material appearance will be relevant? If the object will be only an emitter, do we need exporte all the material/texture information to this kind of light?
It's because sometimes the light color cannot represent what we see:


I need these king of informations in order to export correctly the informations.
Let's make this exporter better!