71 lines
1.8 KiB
C++
71 lines
1.8 KiB
C++
// This file is part of meshoptimizer library; see meshoptimizer.h for version/license details
|
|
#include "meshoptimizer.h"
|
|
|
|
#include <assert.h>
|
|
|
|
unsigned short meshopt_quantizeHalf(float v)
|
|
{
|
|
union { float f; unsigned int ui; } u = {v};
|
|
unsigned int ui = u.ui;
|
|
|
|
int s = (ui >> 16) & 0x8000;
|
|
int em = ui & 0x7fffffff;
|
|
|
|
// bias exponent and round to nearest; 112 is relative exponent bias (127-15)
|
|
int h = (em - (112 << 23) + (1 << 12)) >> 13;
|
|
|
|
// underflow: flush to zero; 113 encodes exponent -14
|
|
h = (em < (113 << 23)) ? 0 : h;
|
|
|
|
// overflow: infinity; 143 encodes exponent 16
|
|
h = (em >= (143 << 23)) ? 0x7c00 : h;
|
|
|
|
// NaN; note that we convert all types of NaN to qNaN
|
|
h = (em > (255 << 23)) ? 0x7e00 : h;
|
|
|
|
return (unsigned short)(s | h);
|
|
}
|
|
|
|
float meshopt_quantizeFloat(float v, int N)
|
|
{
|
|
assert(N >= 0 && N <= 23);
|
|
|
|
union { float f; unsigned int ui; } u = {v};
|
|
unsigned int ui = u.ui;
|
|
|
|
const int mask = (1 << (23 - N)) - 1;
|
|
const int round = (1 << (23 - N)) >> 1;
|
|
|
|
int e = ui & 0x7f800000;
|
|
unsigned int rui = (ui + round) & ~mask;
|
|
|
|
// round all numbers except inf/nan; this is important to make sure nan doesn't overflow into -0
|
|
ui = e == 0x7f800000 ? ui : rui;
|
|
|
|
// flush denormals to zero
|
|
ui = e == 0 ? 0 : ui;
|
|
|
|
u.ui = ui;
|
|
return u.f;
|
|
}
|
|
|
|
float meshopt_dequantizeHalf(unsigned short h)
|
|
{
|
|
unsigned int s = unsigned(h & 0x8000) << 16;
|
|
int em = h & 0x7fff;
|
|
|
|
// bias exponent and pad mantissa with 0; 112 is relative exponent bias (127-15)
|
|
int r = (em + (112 << 10)) << 13;
|
|
|
|
// denormal: flush to zero
|
|
r = (em < (1 << 10)) ? 0 : r;
|
|
|
|
// infinity/NaN; note that we preserve NaN payload as a byproduct of unifying inf/nan cases
|
|
// 112 is an exponent bias fixup; since we already applied it once, applying it twice converts 31 to 255
|
|
r += (em >= (31 << 10)) ? (112 << 23) : 0;
|
|
|
|
union { float f; unsigned int ui; } u;
|
|
u.ui = s | r;
|
|
return u.f;
|
|
}
|