mirror/oot
1
0
Fork 0
mirror of https://github.com/zeldaret/oot synced 2026-06-24 09:41:27 -04:00
Code Issues Packages Projects Releases Wiki Activity

Lightweight trigonometry doc (#1356)

Browse Source 
* Doc units of trig functions

* "Very simple" yet I made a mistake

* sins returns in [-0x7FFF,0x7FFF] as the [-1,1] range

* Also `sys_math_atan.c`

* Remove `@param`s without descriptions

* Add note on Math_Atan2S/F arguments being unlike atan2

* "from (1,0) to (x,y)" -> "from vector ..."

* arg names -> `angle`

* Improve `@return` comment on atans
This commit is contained in:
Dragorn421
2022-10-15 23:29:36 +02:00
committed by GitHub
parent 0b38f6e678
commit 0283493db8
10 changed files with 104 additions and 40 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/code/sys_math_atan.c
+28 -12
View File
@@ -1,6 +1,6 @@
#include "global.h"
static u16 sATan2Tbl[] = {
static u16 sAtan2Tbl[] = {
0x0000, 0x000A, 0x0014, 0x001F, 0x0029, 0x0033, 0x003D, 0x0047, 0x0051, 0x005C, 0x0066, 0x0070, 0x007A, 0x0084,
0x008F, 0x0099, 0x00A3, 0x00AD, 0x00B7, 0x00C2, 0x00CC, 0x00D6, 0x00E0, 0x00EA, 0x00F4, 0x00FF, 0x0109, 0x0113,
0x011D, 0x0127, 0x0131, 0x013C, 0x0146, 0x0150, 0x015A, 0x0164, 0x016F, 0x0179, 0x0183, 0x018D, 0x0197, 0x01A1,
@@ -77,24 +77,34 @@ static u16 sATan2Tbl[] = {
0x1FF6, 0x1FFB, 0x2000,
};
u16 Math_GetAtan2Tbl(f32 x, f32 y) {
/**
* @param y must be >= 0 and <= x
* @param x must be >= 0
* @return arctan(y/x) as binang, in [0,0x2000] range
*/
u16 Math_GetAtan2Tbl(f32 y, f32 x) {
u16 ret;
if (y == 0.0f) {
ret = sATan2Tbl[0];
if (x == 0.0f) {
ret = sAtan2Tbl[0];
} else {
s32 tblIdx = ((x / y) * 1024.0f) + 0.5f;
s32 tblIdx = ((y / x) * 1024.0f) + 0.5f;
if (tblIdx >= ARRAY_COUNT(sATan2Tbl)) {
ret = sATan2Tbl[0];
if (tblIdx >= ARRAY_COUNT(sAtan2Tbl)) {
ret = sAtan2Tbl[0];
} else {
ret = sATan2Tbl[tblIdx];
ret = sAtan2Tbl[tblIdx];
}
}
return ret;
}
/**
* @return angle to (x,y) from vector (1,0) around (0,0) as binang, in [-0x8000,0x7FFF] range
*
* @note The arguments are (x,y), which is different from atan2's (y,x)
*/
s16 Math_Atan2S(f32 x, f32 y) {
s32 ret;
@@ -107,7 +117,7 @@ s16 Math_Atan2S(f32 x, f32 y) {
}
} else {
if (-x < y) {
ret = Math_GetAtan2Tbl(-x, y) + 0x4000;
ret = 0x4000 + Math_GetAtan2Tbl(-x, y);
} else {
ret = 0x8000 - Math_GetAtan2Tbl(y, -x);
}
@@ -115,21 +125,27 @@ s16 Math_Atan2S(f32 x, f32 y) {
} else {
if (x < 0.0f) {
if (-y <= -x) {
ret = Math_GetAtan2Tbl(-y, -x) + 0x8000;
ret = 0x8000 + Math_GetAtan2Tbl(-y, -x);
} else {
ret = 0xC000 - Math_GetAtan2Tbl(-x, -y);
}
} else {
if (x < -y) {
ret = Math_GetAtan2Tbl(x, -y) + 0xC000;
ret = 0xC000 + Math_GetAtan2Tbl(x, -y);
} else {
ret = -Math_GetAtan2Tbl(-y, x);
}
}
}
return ret;
return (s16)ret;
}
/**
* @return angle to (x,y) from vector (1,0) around (0,0) in radians, in [-pi,pi) range
*
* @note The arguments are (x,y), which is different from atan2's (y,x)
*/
f32 Math_Atan2F(f32 x, f32 y) {
return BINANG_TO_RAD(Math_Atan2S(x, y));
}