On 07/10/2016 08:37 AM, Le_Forgeron wrote:
> Le 10/07/2016 14:30, William F Pokorny a écrit :
>> On 07/09/2016 08:32 PM, Jim Holsenback wrote:
>>> On 7/7/2016 1:48 PM, Le_Forgeron wrote:
>>>> I would suggest to leave "Numeric_Expressions" as it is so far, and
>>>> adding, in both "Vector_Expressions" and "Colour_Expressions", a
>>>> dedicated section about getting individual component out of a vector
>>>> and colour.
>>>
>>>
http://wiki.povray.org/content/Documentation:Reference_Table_of_Contents#Scene_Description_Language
>>>
>> On the page:
>>
>> http://wiki.povray.org/content?title=Reference:Color_Expressions
>>
>> wondering about the brackets around rgbft? I think there is no reason for them.
>>
>> COLOR_VECTOR:
>>      rgb <3_Term_Vector>    |
>>      rgbf <4_Term_Vector>   |
>>      rgbt <4_Term_Vector>   |
>>      [ rgbft ] <5_Term_Vector> |
>>      srgb <3_Term_Vector>   |
>>      srgbf <4_Term_Vector>  |
>>      srgbt <4_Term_Vector>  |
>>      srgbft <5_Term_Vector>
>>
>> Bill P.
>
> Actually, they are meaningful : a 5D vector would be interpreted as a rgbft colour
when nothing else is present (aka rgbft is implict).
>
OK. If the optionality is what we are trying to indicate, I think we 
probably want something like :

COLOR_VECTOR:
      [rgb] float            | (promoted to 3 value vector)
      [rg0] <2 Term Vector>  |
      [rgb] <3_Term_Vector>  |
      [rgbf] <4_Term_Vector> |
      rgbt <4_Term_Vector>   |
      [ rgbft ] <5_Term_Vector> |
      srgb <3_Term_Vector>   |
      srgbf <4_Term_Vector>  |
      srgbt <4_Term_Vector>  |
      srgbft <5_Term_Vector>

Bill P.

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