Hi folks,

a new set of semi-official Windows binaries of the current development 
branch can be found at:

https://github.com/c-lipka/povray/releases/tag/v3.7.1-alpha.7918791

Don't be alarmed at the "alpha" version number; being only a 
semi-official release, it simply lacks an official beta number.


As always, Unix jockeys can find the latest and greatest dev source code at:

https://github.com/POV-Ray/povray

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Thanks. Are there particular things we need to be aware of or we need to 
look for?

-- 
Thomas

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Am 23.01.2015 um 09:13 schrieb Thomas de Groot:
> Thanks. Are there particular things we need to be aware of or we need to
> look for?

Under the hood, so much has changed that you'll probably want to keep an 
eye on anything suspicious.


There's one potentially breaking change: Where the parser expects a 
filename, it used to ignore (most) escape sequences; while this allowed 
the easy use of backslashes in literal filenames, it was obviously 
inconsistent and never really documented. Specifying "#version 3.71" 
will cause backslashes to be treated consistently in all string literals.


A few changes to SDL worth experimenting with:


* More realistic finish:

- Radiosity now fully supports brilliance; specify "brilliance on" in 
the global radiosity settings to activate.

- Brilliance is now taken into account not only for incoming light, but 
also for outgoing light; specify "brilliance FLOAT,FLOAT" to activate 
(set both values to same for most realistic results).

- Fresnel angle-dependent attenuation is now also available for 
highlights and diffuse; specify "fresnel on" directly in the finish 
block (another "fresnel on" is still needed in the reflection block).


* Nonlinear colour map and pigment map gradients:

- Specify "blend_mode 1" in a colour or pigment map to force linear 
interpolation regardless of assumed_gamma, which is presumed to be 
physically most realistic, and has also proven to give visually pleasing 
colour gradients.

- Specify "blend_mode 2 blend_gamma FLOAT" to force non-linear 
interpolation as if assumed_gamma was set to FLOAT (defaulting to 2.5), 
which is known to give visually pleasing brightness gradients.

- Specify "blend_mode 3 blend_gamma FLOAT" to force non-linear 
interpolation of luminance, while forcing linear interpolation of 
chromaticity, to give gradients that are visually pleasing with respect 
to both brightness and colour.


* True inverse-power-law light fading:

- Specify "fade_power FLOAT fade_distance 0" (with FLOAT=2 for physical 
realism) to have the light intensity follow a true inverse power law, 
reaching nominal intensity at a distance of 1 unit (requires #version 3.71).


A few other highlights since v3.7.0 release proper:

* Removed limit of 256 entries per blend map.
* Removed limit of 1000000 components per blob.
* Improved accuracy of media sampling in mode 3.

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This:
       color_map {
         blend_mode 1
         [0.10  color Red transmit 0.5]
         [0.50  color Green transmit 0.5]
         [0.90  color Yellow transmit 0.5]
       }
gives a parse error: Must have at least one color in color map

This:
       pigment_map {
         blend_mode 1
         [0.10  rgb <1,0,0> transmit 0.5]
         [0.50  rgb <0,1,0> transmit 0.5]
         [0.90  rgb <1,1,0> transmit 0.5]
       }
works correctly.

-- 
Thomas

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Second comment: Changing blend_gamma in blend_mode 3 does not make any 
visible difference. All settings equal to blend_mode 1.

-- 
Thomas

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Am 26.01.2015 um 13:20 schrieb Thomas de Groot:
> This:
>        color_map {
>          blend_mode 1
>          [0.10  color Red transmit 0.5]
>          [0.50  color Green transmit 0.5]
>          [0.90  color Yellow transmit 0.5]
>        }
> gives a parse error: Must have at least one color in color map

Whoops - to my surprise you're right.

I'll look into it.

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Am 26.01.2015 um 13:47 schrieb Thomas de Groot:
> Second comment: Changing blend_gamma in blend_mode 3 does not make any
> visible difference. All settings equal to blend_mode 1.

If your transitions are between different colours, with not much 
difference in brightness, then that is to be expected.

If your transitions are between different brightness levels, with not 
much difference in colour, then I am inclined to attribute your 
observation to you doing something wrong ;)


Here's what I get with blend_mode 3, and blend_gamma varying from 0.5 
(left) to 2.5 (center) to 7.5 (right). Note the differences in the 
struts connected to the black ball.

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Attachments:
Download 'gradients.png' (95 KB)

Preview of image 'gradients.png'

Am 26.01.2015 um 21:53 schrieb clipka:
> Am 26.01.2015 um 13:20 schrieb Thomas de Groot:
>> This:
>>        color_map {
>>          blend_mode 1
>>          [0.10  color Red transmit 0.5]
>>          [0.50  color Green transmit 0.5]
>>          [0.90  color Yellow transmit 0.5]
>>        }
>> gives a parse error: Must have at least one color in color map
>
> Whoops - to my surprise you're right.
>
> I'll look into it.

Fixed with commit 44d47df. As a preliminary workaround until a new 
Windows binary is released, I suggest simply replacing "color_map" with 
"pigment_map".

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On 26-1-2015 22:11, clipka wrote:
> Am 26.01.2015 um 13:47 schrieb Thomas de Groot:
>> Second comment: Changing blend_gamma in blend_mode 3 does not make any
>> visible difference. All settings equal to blend_mode 1.
>
> If your transitions are between different colours, with not much
> difference in brightness, then that is to be expected.
>
> If your transitions are between different brightness levels, with not
> much difference in colour, then I am inclined to attribute your
> observation to you doing something wrong ;)
>
>
> Here's what I get with blend_mode 3, and blend_gamma varying from 0.5
> (left) to 2.5 (center) to 7.5 (right). Note the differences in the
> struts connected to the black ball.
>
OK! My experiment was mainly with fairly equal brightness. I see now 
what you mean. Thanks!

-- 
Thomas

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