[Cogl] [PATCH 1/3] color: Add HSL conversion functions
Robert Bragg
robert at sixbynine.org
Tue May 28 06:35:23 PDT 2013
I just realized that this bit also needs to initialize the alpha component:
+ if (saturation == 0)
+ {
+ color->red = color->green = color->blue = (luminance * 255);
+
+ return;
+ }
regards,
- Robert
On Tue, May 28, 2013 at 2:30 PM, Robert Bragg <robert at sixbynine.org> wrote:
> These look like good additions to me, and would save us duplicating
> the same kind of code in Rig too. Maybe later we might even want to
> consider the _init_from_string(), _to_string() and _interpolate() apis
> we have in Rig.
>
> Comparing with the similar code we have in Rig, I noticed that
> cogl_color_init_from_hsl() doesn't initialize the alpha component, so
> I think it needs a color->alpha = 1.0; at the end.
>
> As a minor detail we have also switched to updating the gtk-doc
> "Since:" attributes to reflect the actual cogl version we next expect
> to release with the api (i.e. 1.16) instead of the more vague "2.0"
> value since we were getting lots of apis bundled under "2.0" and it
> wasn't very meaningful.
>
> With those small tweaks though I think this patch looks good to land to me:
>
> Reviewed-by: Robert Bragg <robert at linux.intel.com>
>
> thanks,
> - Robert
>
> On Sun, May 19, 2013 at 6:04 AM, Damien Lespiau
> <damien.lespiau at intel.com> wrote:
>> This allows to easily caculate shades of the same color or pick colors
>> with the same saturation/luminance. In short, all sorts of interesting
>> things.
>> ---
>> cogl/cogl-color.c | 129 +++++++++++++++++++++++++++++++++
>> cogl/cogl-color.h | 38 ++++++++++
>> doc/reference/cogl2/cogl2-sections.txt | 4 +
>> 3 files changed, 171 insertions(+)
>>
>> diff --git a/cogl/cogl-color.c b/cogl/cogl-color.c
>> index 9ed1e15..0dba9da 100644
>> --- a/cogl/cogl-color.c
>> +++ b/cogl/cogl-color.c
>> @@ -266,6 +266,135 @@ cogl_color_free (CoglColor *color)
>> }
>>
>> void
>> +cogl_color_to_hsl (const CoglColor *color,
>> + float *hue,
>> + float *luminance,
>> + float *saturation)
>> +{
>> + float red, green, blue;
>> + float min, max, delta;
>> + float h, l, s;
>> +
>> + red = color->red;
>> + green = color->green;
>> + blue = color->blue;
>> +
>> + if (red > green)
>> + {
>> + if (red > blue)
>> + max = red;
>> + else
>> + max = blue;
>> +
>> + if (green < blue)
>> + min = green;
>> + else
>> + min = blue;
>> + }
>> + else
>> + {
>> + if (green > blue)
>> + max = green;
>> + else
>> + max = blue;
>> +
>> + if (red < blue)
>> + min = red;
>> + else
>> + min = blue;
>> + }
>> +
>> + l = (max + min) / 2;
>> + s = 0;
>> + h = 0;
>> +
>> + if (max != min)
>> + {
>> + if (l <= 0.5)
>> + s = (max - min) / (max + min);
>> + else
>> + s = (max - min) / (2.0 - max - min);
>> +
>> + delta = max - min;
>> +
>> + if (red == max)
>> + h = (green - blue) / delta;
>> + else if (green == max)
>> + h = 2.0 + (blue - red) / delta;
>> + else if (blue == max)
>> + h = 4.0 + (red - green) / delta;
>> +
>> + h *= 60;
>> +
>> + if (h < 0)
>> + h += 360.0;
>> + }
>> +
>> + if (hue)
>> + *hue = h;
>> +
>> + if (luminance)
>> + *luminance = l;
>> +
>> + if (saturation)
>> + *saturation = s;
>> +}
>> +
>> +void
>> +cogl_color_init_from_hsl (CoglColor *color,
>> + float hue,
>> + float luminance,
>> + float saturation)
>> +{
>> + float tmp1, tmp2;
>> + float tmp3[3];
>> + float clr[3];
>> + int i;
>> +
>> + hue /= 360.0;
>> +
>> + if (saturation == 0)
>> + {
>> + color->red = color->green = color->blue = (luminance * 255);
>> +
>> + return;
>> + }
>> +
>> + if (luminance <= 0.5)
>> + tmp2 = luminance * (1.0 + saturation);
>> + else
>> + tmp2 = luminance + saturation - (luminance * saturation);
>> +
>> + tmp1 = 2.0 * luminance - tmp2;
>> +
>> + tmp3[0] = hue + 1.0 / 3.0;
>> + tmp3[1] = hue;
>> + tmp3[2] = hue - 1.0 / 3.0;
>> +
>> + for (i = 0; i < 3; i++)
>> + {
>> + if (tmp3[i] < 0)
>> + tmp3[i] += 1.0;
>> +
>> + if (tmp3[i] > 1)
>> + tmp3[i] -= 1.0;
>> +
>> + if (6.0 * tmp3[i] < 1.0)
>> + clr[i] = tmp1 + (tmp2 - tmp1) * tmp3[i] * 6.0;
>> + else if (2.0 * tmp3[i] < 1.0)
>> + clr[i] = tmp2;
>> + else if (3.0 * tmp3[i] < 2.0)
>> + clr[i] = (tmp1 + (tmp2 - tmp1) * ((2.0 / 3.0) - tmp3[i]) * 6.0);
>> + else
>> + clr[i] = tmp1;
>> + }
>> +
>> + color->red = clr[0];
>> + color->green = clr[1];
>> + color->blue = clr[2];
>> +}
>> +
>> +void
>> _cogl_color_get_rgba_4fv (const CoglColor *color,
>> float *dest)
>> {
>> diff --git a/cogl/cogl-color.h b/cogl/cogl-color.h
>> index 94726a4..7e520a9 100644
>> --- a/cogl/cogl-color.h
>> +++ b/cogl/cogl-color.h
>> @@ -485,6 +485,44 @@ cogl_color_copy (const CoglColor *color);
>> void
>> cogl_color_free (CoglColor *color);
>>
>> +/**
>> + * cogl_color_to_hsl:
>> + * @color: a #CoglColor
>> + * @hue: (out): return location for the hue value or %NULL
>> + * @luminance: (out): return location for the luminance value or %NULL
>> + * @saturation: (out): return location for the saturation value or %NULL
>> + *
>> + * Converts @color to the HLS format.
>> + *
>> + * The @hue value is in the 0 .. 360 range. The @luminance and
>> + * @saturation values are in the 0 .. 1 range.
>> + *
>> + * Since: 2.0
>> + */
>> +void
>> +cogl_color_to_hsl (const CoglColor *color,
>> + float *hue,
>> + float *luminance,
>> + float *saturation);
>> +
>> +/**
>> + * cogl_color_init_from_hsl:
>> + * @color: (out): return location for a #CoglColor
>> + * @hue: hue value, in the 0 .. 360 range
>> + * @luminance: luminance value, in the 0 .. 1 range
>> + * @saturation: saturation value, in the 0 .. 1 range
>> + *
>> + * Converts a color expressed in HLS (hue, luminance and saturation)
>> + * values into a #CoglColor.
>> + *
>> + * Since: 2.0
>> + */
>> +void
>> +cogl_color_init_from_hsl (CoglColor *color,
>> + float hue,
>> + float luminance,
>> + float saturation);
>> +
>> COGL_END_DECLS
>>
>> #endif /* __COGL_COLOR_H__ */
>> diff --git a/doc/reference/cogl2/cogl2-sections.txt b/doc/reference/cogl2/cogl2-sections.txt
>> index 68769bd..4ac1148 100644
>> --- a/doc/reference/cogl2/cogl2-sections.txt
>> +++ b/doc/reference/cogl2/cogl2-sections.txt
>> @@ -628,6 +628,10 @@ cogl_color_set_alpha_float
>> cogl_color_premultiply
>> cogl_color_unpremultiply
>> cogl_color_equal
>> +
>> +<SUBSECTION>
>> +cogl_color_init_from_hls
>> +cogl_color_to_hls
>> </SECTION>
>>
>> <SECTION>
>> --
>> 1.8.1.4
>>
>> _______________________________________________
>> Cogl mailing list
>> Cogl at lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/cogl
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