veclavtlica
87 lines
3.1 KiB
C
87 lines
3.1 KiB
C
/*
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Fixed point implementation of 3 dimensional vectors.
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SSE2 extension availability is assumed, making it more viable.
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For mul and div we don't use com_fixed functions to make fewer bitshifts.
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*/
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#ifndef COM_VEC_H
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#define COM_VEC_H
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#include "def.h"
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#include "fixed.h"
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#include <stdint.h>
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typedef union {
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com_fixed_t com_def_alignedas(16) a[3];
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com_def_alignedas(16) struct {
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com_fixed_t x;
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com_fixed_t y;
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com_fixed_t z;
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} s;
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} com_vec_t;
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static inline com_vec_t com_vec_identity(void) {
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return (com_vec_t){.s = {.x = COM_FIXED_FRACUNIT,
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.y = COM_FIXED_FRACUNIT,
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.z = COM_FIXED_FRACUNIT}};
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}
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static inline com_vec_t com_vec_add(com_vec_t a, com_vec_t b) {
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return (com_vec_t){.s = {.x = com_fixed_add(a.s.x, b.s.x),
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.y = com_fixed_add(a.s.y, b.s.y),
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.z = com_fixed_add(a.s.z, b.s.z)}};
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}
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static inline com_vec_t com_vec_sub(com_vec_t a, com_vec_t b) {
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return (com_vec_t){.s = {.x = com_fixed_sub(a.s.x, b.s.x),
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.y = com_fixed_sub(a.s.y, b.s.y),
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.z = com_fixed_sub(a.s.z, b.s.z)}};
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}
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static inline com_vec_t com_vec_mul(com_vec_t a, com_vec_t b) {
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return (com_vec_t){.s = {.x = com_fixed_mul(a.s.x, b.s.x),
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.y = com_fixed_mul(a.s.y, b.s.y),
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.z = com_fixed_mul(a.s.z, b.s.z)}};
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}
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/* Note: this does not clamp for over/underflow cases */
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static inline com_vec_t com_vec_div(com_vec_t a, com_vec_t b) {
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return (com_vec_t){.s = {.x = com_fixed_div(a.s.x, b.s.x),
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.y = com_fixed_div(a.s.y, b.s.y),
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.z = com_fixed_div(a.s.z, b.s.z)}};
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}
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/* Scale vector by a fixed point number */
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static inline com_vec_t com_vec_scl(com_vec_t a, com_fixed_t b) {
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return (com_vec_t){.s = {.x = com_fixed_mul(a.s.x, b),
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.y = com_fixed_mul(a.s.y, b),
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.z = com_fixed_mul(a.s.z, b)}};
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}
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/* Shows how much given vectors are correlated in direction to each other */
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/* Resulted range depends on input, it's in -1 to 1 for normalized
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* input and otherwise is -ab to +ab */
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static inline com_fixed_t com_vec_dot(com_vec_t a, com_vec_t b) {
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return (((int64_t)a.s.x * b.s.x) + ((int64_t)a.s.y * b.s.y) +
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((int64_t)a.s.z * b.s.z)) >>
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COM_FIXED_FRACBITS;
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}
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/* Cross product produces a perpendicular for normalized vectors, or 0 for
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* parallel vectors */
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static inline com_vec_t com_vec_crs(com_vec_t a, com_vec_t b) {
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int64_t const cx = ((int64_t)a.s.y * b.s.z) - ((int64_t)a.s.z - b.s.y);
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int64_t const cy = ((int64_t)a.s.z * b.s.x) - ((int64_t)a.s.x - b.s.z);
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int64_t const cz = ((int64_t)a.s.x * b.s.y) - ((int64_t)a.s.y - b.s.x);
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return (com_vec_t){.s = {.x = (com_fixed_t)(cx >> COM_FIXED_FRACBITS),
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.y = (com_fixed_t)(cy >> COM_FIXED_FRACBITS),
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.z = (com_fixed_t)(cz >> COM_FIXED_FRACBITS)}};
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}
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static inline com_vec_t com_vec_nrm(com_vec_t a) {
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com_fixed_t const n = com_fixed_sqrt(com_vec_dot(a, a));
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return com_vec_scl(a, com_fixed_div(COM_FIXED_FRACUNIT, n));
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}
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#endif
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