#include "nuklear.h"
#include "nuklear_internal.h"
/* ===============================================================
*
* MATH
*
* ===============================================================*/
/*/// ### Math
/// Since nuklear is supposed to work on all systems providing floating point
/// math without any dependencies I also had to implement my own math functions
/// for sqrt, sin and cos. Since the actual highly accurate implementations for
/// the standard library functions are quite complex and I do not need high
/// precision for my use cases I use approximations.
///
/// Sqrt
/// ----
/// For square root nuklear uses the famous fast inverse square root:
/// https://en.wikipedia.org/wiki/Fast_inverse_square_root with
/// slightly tweaked magic constant. While on today's hardware it is
/// probably not faster it is still fast and accurate enough for
/// nuklear's use cases. IMPORTANT: this requires float format IEEE 754
///
/// Sine/Cosine
/// -----------
/// All constants inside both function are generated Remez's minimax
/// approximations for value range 0...2*PI. The reason why I decided to
/// approximate exactly that range is that nuklear only needs sine and
/// cosine to generate circles which only requires that exact range.
/// In addition I used Remez instead of Taylor for additional precision:
/// www.lolengine.net/blog/2011/12/21/better-function-approximations.
///
/// The tool I used to generate constants for both sine and cosine
/// (it can actually approximate a lot more functions) can be
/// found here: www.lolengine.net/wiki/oss/lolremez
*/
#ifndef NK_INV_SQRT
#define NK_INV_SQRT nk_inv_sqrt
NK_LIB float
nk_inv_sqrt(float n)
{
float x2;
const float threehalfs = 1.5f;
union {nk_uint i; float f;} conv = {0};
conv.f = n;
x2 = n * 0.5f;
conv.i = 0x5f375A84 - (conv.i >> 1);
conv.f = conv.f * (threehalfs - (x2 * conv.f * conv.f));
return conv.f;
}
#endif
#ifndef NK_SIN
#define NK_SIN nk_sin
NK_LIB float
nk_sin(float x)
{
NK_STORAGE const float a0 = +1.91059300966915117e-31f;
NK_STORAGE const float a1 = +1.00086760103908896f;
NK_STORAGE const float a2 = -1.21276126894734565e-2f;
NK_STORAGE const float a3 = -1.38078780785773762e-1f;
NK_STORAGE const float a4 = -2.67353392911981221e-2f;
NK_STORAGE const float a5 = +2.08026600266304389e-2f;
NK_STORAGE const float a6 = -3.03996055049204407e-3f;
NK_STORAGE const float a7 = +1.38235642404333740e-4f;
return a0 + x*(a1 + x*(a2 + x*(a3 + x*(a4 + x*(a5 + x*(a6 + x*a7))))));
}
#endif
#ifndef NK_COS
#define NK_COS nk_cos
NK_LIB float
nk_cos(float x)
{
/* New implementation. Also generated using lolremez. */
/* Old version significantly deviated from expected results. */
NK_STORAGE const float a0 = 9.9995999154986614e-1f;
NK_STORAGE const float a1 = 1.2548995793001028e-3f;
NK_STORAGE const float a2 = -5.0648546280678015e-1f;
NK_STORAGE const float a3 = 1.2942246466519995e-2f;
NK_STORAGE const float a4 = 2.8668384702547972e-2f;
NK_STORAGE const float a5 = 7.3726485210586547e-3f;
NK_STORAGE const float a6 = -3.8510875386947414e-3f;
NK_STORAGE const float a7 = 4.7196604604366623e-4f;
NK_STORAGE const float a8 = -1.8776444013090451e-5f;
return a0 + x*(a1 + x*(a2 + x*(a3 + x*(a4 + x*(a5 + x*(a6 + x*(a7 + x*a8)))))));
}
#endif
NK_LIB nk_uint
nk_round_up_pow2(nk_uint v)
{
v--;
v |= v >> 1;
v |= v >> 2;
v |= v >> 4;
v |= v >> 8;
v |= v >> 16;
v++;
return v;
}
NK_LIB double
nk_pow(double x, int n)
{
/* check the sign of n */
double r = 1;
int plus = n >= 0;
n = (plus) ? n : -n;
while (n > 0) {
if ((n & 1) == 1)
r *= x;
n /= 2;
x *= x;
}
return plus ? r : 1.0 / r;
}
NK_LIB int
nk_ifloord(double x)
{
x = (double)((int)x - ((x < 0.0) ? 1 : 0));
return (int)x;
}
NK_LIB int
nk_ifloorf(float x)
{
x = (float)((int)x - ((x < 0.0f) ? 1 : 0));
return (int)x;
}
NK_LIB int
nk_iceilf(float x)
{
if (x >= 0) {
int i = (int)x;
return (x > i) ? i+1: i;
} else {
int t = (int)x;
float r = x - (float)t;
return (r > 0.0f) ? t+1: t;
}
}
NK_LIB int
nk_log10(double n)
{
int neg;
int ret;
int exp = 0;
neg = (n < 0) ? 1 : 0;
ret = (neg) ? (int)-n : (int)n;
while ((ret / 10) > 0) {
ret /= 10;
exp++;
}
if (neg) exp = -exp;
return exp;
}
NK_API struct nk_rect
nk_get_null_rect(void)
{
return nk_null_rect;
}
NK_API struct nk_rect
nk_rect(float x, float y, float w, float h)
{
struct nk_rect r;
r.x = x; r.y = y;
r.w = w; r.h = h;
return r;
}
NK_API struct nk_rect
nk_recti(int x, int y, int w, int h)
{
struct nk_rect r;
r.x = (float)x;
r.y = (float)y;
r.w = (float)w;
r.h = (float)h;
return r;
}
NK_API struct nk_rect
nk_recta(struct nk_vec2 pos, struct nk_vec2 size)
{
return nk_rect(pos.x, pos.y, size.x, size.y);
}
NK_API struct nk_rect
nk_rectv(const float *r)
{
return nk_rect(r[0], r[1], r[2], r[3]);
}
NK_API struct nk_rect
nk_rectiv(const int *r)
{
return nk_recti(r[0], r[1], r[2], r[3]);
}
NK_API struct nk_vec2
nk_rect_pos(struct nk_rect r)
{
struct nk_vec2 ret;
ret.x = r.x; ret.y = r.y;
return ret;
}
NK_API struct nk_vec2
nk_rect_size(struct nk_rect r)
{
struct nk_vec2 ret;
ret.x = r.w; ret.y = r.h;
return ret;
}
NK_LIB struct nk_rect
nk_shrink_rect(struct nk_rect r, float amount)
{
struct nk_rect res;
r.w = NK_MAX(r.w, 2 * amount);
r.h = NK_MAX(r.h, 2 * amount);
res.x = r.x + amount;
res.y = r.y + amount;
res.w = r.w - 2 * amount;
res.h = r.h - 2 * amount;
return res;
}
NK_LIB struct nk_rect
nk_pad_rect(struct nk_rect r, struct nk_vec2 pad)
{
r.w = NK_MAX(r.w, 2 * pad.x);
r.h = NK_MAX(r.h, 2 * pad.y);
r.x += pad.x; r.y += pad.y;
r.w -= 2 * pad.x;
r.h -= 2 * pad.y;
return r;
}
NK_API struct nk_vec2
nk_vec2(float x, float y)
{
struct nk_vec2 ret;
ret.x = x; ret.y = y;
return ret;
}
NK_API struct nk_vec2
nk_vec2i(int x, int y)
{
struct nk_vec2 ret;
ret.x = (float)x;
ret.y = (float)y;
return ret;
}
NK_API struct nk_vec2
nk_vec2v(const float *v)
{
return nk_vec2(v[0], v[1]);
}
NK_API struct nk_vec2
nk_vec2iv(const int *v)
{
return nk_vec2i(v[0], v[1]);
}
NK_LIB void
nk_unify(struct nk_rect *clip, const struct nk_rect *a, float x0, float y0,
float x1, float y1)
{
NK_ASSERT(a);
NK_ASSERT(clip);
clip->x = NK_MAX(a->x, x0);
clip->y = NK_MAX(a->y, y0);
clip->w = NK_MIN(a->x + a->w, x1) - clip->x;
clip->h = NK_MIN(a->y + a->h, y1) - clip->y;
clip->w = NK_MAX(0, clip->w);
clip->h = NK_MAX(0, clip->h);
}
NK_API void
nk_triangle_from_direction(struct nk_vec2 *result, struct nk_rect r,
float pad_x, float pad_y, enum nk_heading direction)
{
float w_half, h_half;
NK_ASSERT(result);
r.w = NK_MAX(2 * pad_x, r.w);
r.h = NK_MAX(2 * pad_y, r.h);
r.w = r.w - 2 * pad_x;
r.h = r.h - 2 * pad_y;
r.x = r.x + pad_x;
r.y = r.y + pad_y;
w_half = r.w / 2.0f;
h_half = r.h / 2.0f;
if (direction == NK_UP) {
result[0] = nk_vec2(r.x + w_half, r.y);
result[1] = nk_vec2(r.x + r.w, r.y + r.h);
result[2] = nk_vec2(r.x, r.y + r.h);
} else if (direction == NK_RIGHT) {
result[0] = nk_vec2(r.x, r.y);
result[1] = nk_vec2(r.x + r.w, r.y + h_half);
result[2] = nk_vec2(r.x, r.y + r.h);
} else if (direction == NK_DOWN) {
result[0] = nk_vec2(r.x, r.y);
result[1] = nk_vec2(r.x + r.w, r.y);
result[2] = nk_vec2(r.x + w_half, r.y + r.h);
} else {
result[0] = nk_vec2(r.x, r.y + h_half);
result[1] = nk_vec2(r.x + r.w, r.y);
result[2] = nk_vec2(r.x + r.w, r.y + r.h);
}
}