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Converted C++ comments to C89 and added reference

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Single line comment are a feature of C++ and C99 and above while C89 only
supports multiline comment /**/. In addition I added an additional
reference for the addition and subtraction formulae.
This commit is contained in:
vurtun 2017-08-12 17:53:37 +02:00
parent 4ba164c17b
commit bee9037028
1 changed files with 17 additions and 16 deletions
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33
nuklear.h
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@ -8587,23 +8587,24 @@ nk_draw_list_path_arc_to(struct nk_draw_list *list, struct nk_vec2 center,
if (!list) return;
if (radius == 0.0f) return;
// This algorithm for arc drawing relies on
// these two trigonometric identities:
// sin(a + b) = sin(a) * cos(b) + cos(a) * sin(b)
// cos(a + b) = cos(a) * cos(b) - sin(a) * sin(b)
//
// Two coordinates (x, y) of a point on a circle centered on
// the origin can be written in polar form as:
// x = r * cos(a)
// y = r * sin(a)
// where r is the radius of the circle,
// a is the angle between (x, y) and the origin.
//
// This allows us to rotate the coordinates around the
// origin by an angle b using the following transformation:
// x' = r * cos(a + b) = x * cos(b) - y * sin(b)
// y' = r * sin(a + b) = y * cos(b) + x * sin(b)
/* This algorithm for arc drawing relies on these two trigonometric identities[1]:
sin(a + b) = sin(a) * cos(b) + cos(a) * sin(b)
cos(a + b) = cos(a) * cos(b) - sin(a) * sin(b)
Two coordinates (x, y) of a point on a circle centered on
the origin can be written in polar form as:
x = r * cos(a)
y = r * sin(a)
where r is the radius of the circle,
a is the angle between (x, y) and the origin.
This allows us to rotate the coordinates around the
origin by an angle b using the following transformation:
x' = r * cos(a + b) = x * cos(b) - y * sin(b)
y' = r * sin(a + b) = y * cos(b) + x * sin(b)
[1] https://en.wikipedia.org/wiki/List_of_trigonometric_identities#Angle_sum_and_difference_identities
*/
const float d_angle = (a_max - a_min) / (float)segments;
const float sin_d = (float)NK_SIN(d_angle);
const float cos_d = (float)NK_COS(d_angle);