geometry.h File Reference

#include "config.h"
#include <math.h>
#include <float.h>
#include "basic_grid.h"
#include "grid_cell.h"
#include "utils_core.h"

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Data Structures
struct	sin_cos_angle
struct	bounding_circle
struct	yac_circle

Macros
#define	YAC_RAD   (0.01745329251994329576923690768489)
#define	yac_angle_tol   (1e-9)
#define	yac_sq_angle_tol   (1e-9 * 1e-9)
#define	yac_cos_angle_tol   (0.9999999999999999995)
#define	yac_angle_low_tol   (1e-11)
#define	yac_cos_angle_low_tol   (1.0)

Enumerations
enum	yac_circle_type { GREAT_CIRCLE = YAC_GREAT_CIRCLE_EDGE , LAT_CIRCLE = YAC_LAT_CIRCLE_EDGE , LON_CIRCLE = YAC_LON_CIRCLE_EDGE , POINT }

Functions
int	yac_point_in_cell (double point_coords[3], struct yac_grid_cell cell)
int	yac_point_in_cell2 (double point_coords[3], struct yac_grid_cell cell, struct bounding_circle bnd_circle)
static double	get_angle (double a_lon, double b_lon)
static double	get_angle_deg (double a_lon, double b_lon)
int	yac_intersect_vec (enum yac_edge_type edge_type_a, double const a[3], double const b[3], enum yac_edge_type edge_type_b, double const c[3], double const d[3], double p[3], double q[3])
void	yac_get_cell_bounding_circle (struct yac_grid_cell cell, struct bounding_circle *bnd_circle)
void	yac_get_cell_circumscribe_circle_unstruct_triangle (double a[3], double b[3], double c[3], struct bounding_circle *bnd_circle)
void	yac_get_cell_bounding_circle_unstruct_triangle (double a[3], double b[3], double c[3], struct bounding_circle *bnd_circle)
void	yac_get_cell_circumscribe_circle_reg_quad (double a[3], double b[3], double c[3], struct bounding_circle *bnd_circle)
void	yac_get_cell_bounding_circle_reg_quad (double a[3], double b[3], double c[3], struct bounding_circle *bnd_circle)
int	yac_extents_overlap (struct bounding_circle *extent_a, struct bounding_circle *extent_b)
static double	sq_len_diff_vec (double const a[3], double const b[3])
	computes square of the lenght of the vector ab
static double	compute_sq_crd (struct sin_cos_angle angle)
static int	yac_point_in_bounding_circle_vec (double point_vector[3], struct bounding_circle *bnd_circle)
static void	LLtoXYZ (double lon, double lat, double p_out[])
static void	LLtoXYZ_deg (double lon, double lat, double p_out[])
static void	XYZtoLL (double const p_in[], double *lon, double *lat)
static double	det2_kahan (double a, double b, double c, double d)
static void	crossproduct_kahan (double const a[], double const b[], double cross[])
static void	crossproduct_d (const double a[], const double b[], double cross[])
static double	get_vector_angle (double const a[3], double const b[3])
static double	clamp_abs_one (double val)
static struct sin_cos_angle	sin_cos_angle_new (double sin, double cos)
static struct sin_cos_angle	get_vector_angle_2 (double const a[3], double const b[3])
static int	compare_angles (struct sin_cos_angle a, struct sin_cos_angle b)
static double	sin_cos_angle_to_dble (struct sin_cos_angle angle)
static struct sin_cos_angle	sum_angles_no_check (struct sin_cos_angle a, struct sin_cos_angle b)
static int	sum_angles (struct sin_cos_angle a, struct sin_cos_angle b, struct sin_cos_angle *restrict sum)
static struct sin_cos_angle	sub_angles_no_check (struct sin_cos_angle a, struct sin_cos_angle b)
static int	sub_angles (struct sin_cos_angle a, struct sin_cos_angle b, struct sin_cos_angle *restrict sub)
static double	compute_angle (struct sin_cos_angle angle)
	return angles in the range of [0;2PI[
static struct sin_cos_angle	half_angle (struct sin_cos_angle angle)
static struct sin_cos_angle	quarter_angle (struct sin_cos_angle angle)
static int	points_are_identically (double const *a, double const *b)
static int	compare_coords (double const *a, double const *b)
static void	normalise_vector (double v[])
static void	rotate_vector2 (double axis[], struct sin_cos_angle angle, double v_in[], double v_out[])
static void	rotate_vector (double axis[], double angle, double v_in[], double v_out[])
void	yac_triangulate_cell (struct yac_grid_cell cell, size_t start_corner, struct yac_grid_cell *triangles)
void	yac_triangulate_cell_indices (size_t const *corner_indices, size_t num_corners, size_t start_corner, size_t(*triangle_indices)[3])
void	yac_compute_bnd_triangle (double *vertices, size_t num_vertices, double triangle[][3], size_t num_tests)
int	yac_circle_intersect (struct yac_circle a, struct yac_circle b, double p[3], double q[3])
int	yac_point_on_edge (double p[3], double const a[3], double const b[3], enum yac_circle_type circle_type)

Variables
static const struct sin_cos_angle	SIN_COS_ZERO = {0.0, 1.0}
static const struct sin_cos_angle	SIN_COS_TOL = {yac_angle_tol, yac_cos_angle_tol}
static const struct sin_cos_angle	SIN_COS_LOW_TOL = {yac_angle_low_tol, yac_cos_angle_low_tol}
static const struct sin_cos_angle	SIN_COS_M_PI_2 = {1.0, 0.0}
static const struct sin_cos_angle	SIN_COS_M_PI = {0.0, -1.0}
static const struct sin_cos_angle	SIN_COS_7_M_PI_4 = {-0.707106781186547524401, +0.707106781186547524401}

Macro Definition Documentation

yac_angle_low_tol

#define yac_angle_low_tol   (1e-11)

Examples

test_lat_clipping.c.

Definition at line 37 of file geometry.h.

yac_angle_tol

#define yac_angle_tol   (1e-9)

Examples

test_angle.c, test_basic_grid.c, test_circle.c, test_clipping.c, test_interp_grid_parallel.c, test_point_in_cell.c, and test_point_sphere_part.c.

Definition at line 34 of file geometry.h.

yac_cos_angle_low_tol

#define yac_cos_angle_low_tol   (1.0)

Definition at line 38 of file geometry.h.

yac_cos_angle_tol

#define yac_cos_angle_tol   (0.9999999999999999995)

Definition at line 36 of file geometry.h.

YAC_RAD

#define YAC_RAD   (0.01745329251994329576923690768489)

Examples

test_area.c, test_cell_bnd_circle.c, test_clipping.c, test_compute_overlap_area.c, test_couple_config.c, test_dist_grid_pair_parallel.c, test_dummy_coupling2_c.c, test_dummy_coupling3_c.c, test_dummy_coupling5_c.c, test_dummy_coupling6_c.c, test_dummy_coupling7_c.c, test_geometry.c, test_instance_parallel1.c, test_interp_grid_parallel.c, test_interp_method_avg_parallel.c, test_interp_method_callback_parallel.c, test_interp_method_conserv_parallel.c, test_interp_method_creep_parallel.c, test_interp_method_file_parallel.c, test_interp_method_hcsbb_parallel.c, test_interp_method_ncc_parallel.c, test_interp_method_nnn_parallel.c, test_interp_method_rbf_parallel.c, test_interp_method_spmap_parallel.c, test_interpolation_parallel1_c.c, test_interpolation_parallel2.c, test_interpolation_parallel3.c, test_interpolation_parallel4.c, test_interpolation_parallel5.c, test_lat_clipping.c, test_loncxlatc.c, test_partial_areas.c, test_point_in_cell.c, test_read_icon_parallel.c, test_restart_c.c, and test_vtk_output.c.

Definition at line 30 of file geometry.h.

yac_sq_angle_tol

#define yac_sq_angle_tol   (1e-9 * 1e-9)

Definition at line 35 of file geometry.h.

Enumeration Type Documentation

yac_circle_type

enum yac_circle_type

Enumerator
GREAT_CIRCLE
LAT_CIRCLE
LON_CIRCLE
POINT

Definition at line 72 of file geometry.h.

Function Documentation

clamp_abs_one()

static double clamp_abs_one ( double val )

inlinestatic

Definition at line 401 of file geometry.h.

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compare_angles()

static int compare_angles ( struct sin_cos_angle a, struct sin_cos_angle b )

inlinestatic

Examples

test_angle.c, test_cell_bnd_circle.c, and test_point_sphere_part.c.

Definition at line 428 of file geometry.h.

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compare_coords()

static int compare_coords ( double const * a, double const * b )

inlinestatic

compares two 3d coordinates (vectors need to have a length of 1.0)

Parameters

[in]	a	coordinates of point a
[in]	b	coordinates of point b

Returns

0 if points are identical, otherwise -1 or 1 depending on their relation

Definition at line 662 of file geometry.h.

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compute_angle()

static double compute_angle ( struct sin_cos_angle angle )

inlinestatic

return angles in the range of [0;2PI[

Examples

test_angle.c.

Definition at line 572 of file geometry.h.

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compute_sq_crd()

static double compute_sq_crd ( struct sin_cos_angle angle )

inlinestatic

Definition at line 254 of file geometry.h.

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crossproduct_d()

static void crossproduct_d ( const double a[], const double b[], double cross[] )

inlinestatic

for small angles <= 1e-?8? the crossproduct is inaccurate
use crossproduct_kahan for these cases

Definition at line 347 of file geometry.h.

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crossproduct_kahan()

static void crossproduct_kahan ( double const a[], double const b[], double cross[] )

inlinestatic

Definition at line 332 of file geometry.h.

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det2_kahan()

static double det2_kahan ( double a, double b, double c, double d )

inlinestatic

Definition at line 325 of file geometry.h.

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get_angle()

static double get_angle ( double a_lon, double b_lon )

inlinestatic

computes the angle between two longitude coordinates (in rad)
takes into account that longitude have a period of 2 pi

Parameters

[in]	a_lon
[in]	b_lon

Returns

angle between both coordinates (in rad)

Examples

test_geometry.c.

Definition at line 127 of file geometry.h.

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get_angle_deg()

static double get_angle_deg ( double a_lon, double b_lon )

inlinestatic

computes the angle between two longitude coordinates (in deg)
takes into account that longitude have a period of 360

Parameters

[in]	a_lon
[in]	b_lon

Returns

angle between both coordinates (in rad)

Definition at line 143 of file geometry.h.

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get_vector_angle()

static double get_vector_angle ( double const a[3], double const b[3] )

inlinestatic

computes the great circle distance in rad for two points given in xyz coordinates taken from http://johnblackburne.blogspot.de/2012/05/angle-between-two-3d-vectors.html

Parameters

[in]	a	point coordinates of point a
[in]	b	point coordinates of point b

Returns

great circle distance in rad between both points

Examples

test_basic_grid.c, test_circle.c, test_clipping.c, test_compute_overlap_area.c, test_geometry.c, test_interp_grid_parallel.c, test_interp_method_ncc_parallel.c, test_interp_method_nnn_parallel.c, test_interp_method_spmap_parallel.c, test_lat_clipping.c, test_partial_areas.c, and test_point_sphere_part.c.

Definition at line 364 of file geometry.h.

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get_vector_angle_2()

static struct sin_cos_angle get_vector_angle_2 ( double const a[3], double const b[3] )

inlinestatic

Examples

test_cell_bnd_circle.c, test_interp_grid_parallel.c, and test_point_sphere_part.c.

Definition at line 415 of file geometry.h.

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half_angle()

static struct sin_cos_angle half_angle ( struct sin_cos_angle angle )

inlinestatic

computes angle / 2 The basic idea is to imagin angle being a vector v with (cos(x); sin(x)) and w being a vector with (1.0; 0.0). The normalised sum of v and w gives us v_h with (cos(x/2); sin(x/2)). For quadrants 2, 3, and 4 we have to apply some little tricks for higher accuracy.

Examples

test_angle.c.

Definition at line 600 of file geometry.h.

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LLtoXYZ()

static void LLtoXYZ ( double lon, double lat, double p_out[] )

inlinestatic

converts lon-lat coordinates into xyz ones

Further information: http://en.wikipedia.org/wiki/List_of_common_coordinate_transformations

Parameters

[in]	lon	longitude coordinates in radian
[in]	lat	latitude coordinates in radian
[out]	p_out	xyz coordinates

Examples

test_bnd_sphere_part.c, test_cell_bnd_circle.c, test_geometry.c, test_interp_grid_parallel.c, test_interpolation_parallel4.c, test_partial_areas.c, test_point_in_cell.c, and test_point_sphere_part.c.

Definition at line 287 of file geometry.h.

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LLtoXYZ_deg()

static void LLtoXYZ_deg ( double lon, double lat, double p_out[] )

inlinestatic

converts lon-lat coordinates into xyz ones

Parameters

[in]	lon	longitude coordinates in deg
[in]	lat	latitude coordinates in deg
[out]	p_out	xyz coordinates

Examples

test_basic_grid.c, test_basic_grid_data.c, test_circle.c, test_clipping.c, test_compute_overlap_area.c, test_interp_grid_parallel.c, test_interp_method_avg_parallel.c, test_interp_method_conserv_parallel.c, test_interp_method_creep_parallel.c, test_interp_method_ncc_parallel.c, test_interp_method_nnn_parallel.c, test_interp_method_rbf_parallel.c, test_interpolation_parallel2.c, test_interpolation_parallel3.c, test_point_in_cell.c, test_point_sphere_part.c, and test_proc_sphere_part_parallel.c.

Definition at line 304 of file geometry.h.

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normalise_vector()

static void normalise_vector ( double v[] )

inlinestatic

normalises a vector

Examples

test_compute_overlap_area.c, test_instance_parallel1.c, test_interp_grid_parallel.c, test_interp_method_avg_parallel.c, test_interp_method_hcsbb_parallel.c, test_interp_method_spmap_parallel.c, and test_partial_areas.c.

Definition at line 689 of file geometry.h.

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points_are_identically()

static int points_are_identically ( double const * a, double const * b )

inlinestatic

determines whether two given points are (nearly) identically

Parameters

[in]	a	point coordinates of point a
[in]	b	point coordinates of point b

Returns

true if both points are (nearly) identically

Examples

test_point_sphere_part.c.

Definition at line 648 of file geometry.h.

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quarter_angle()

static struct sin_cos_angle quarter_angle ( struct sin_cos_angle angle )

inlinestatic

computes angle / 4 I derived it based on half_angle

Examples

test_angle.c.

Definition at line 617 of file geometry.h.

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rotate_vector()

static void rotate_vector ( double axis[], double angle, double v_in[], double v_out[] )

inlinestatic

rotate vector v_in around the given axis by a given angle

Parameters

[in]	axis	axis around which v_in is to rotated
[in]	angle	rotation angle
[in]	v_in	vector to be rotated
[out]	v_out	rotated vector

Definition at line 732 of file geometry.h.

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rotate_vector2()

static void rotate_vector2 ( double axis[], struct sin_cos_angle angle, double v_in[], double v_out[] )

inlinestatic

rotate vector v_in around the given axis by a given angle

Parameters

[in]	axis	axis around which v_in is to rotated
[in]	angle	rotation angle
[in]	v_in	vector to be rotated
[out]	v_out	rotated vector

Definition at line 704 of file geometry.h.

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sin_cos_angle_new()

static struct sin_cos_angle sin_cos_angle_new ( double sin, double cos )

inlinestatic

Examples

test_angle.c, test_bnd_sphere_part.c, test_point_in_cell.c, and test_point_sphere_part.c.

Definition at line 405 of file geometry.h.

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sin_cos_angle_to_dble()

static double sin_cos_angle_to_dble ( struct sin_cos_angle angle )

inlinestatic

this routine converts a struct sin_cos_angle into a double, which allows to easily compare angles 0: 0 <= angle < PI/4 => ret = 0 * M_SQRT1_2 + sin(angle) 1: PI/4 <= angle < 3*PI/4 => ret = 2 * M_SQRT1_2 - cos(angle) 2: 3*PI/4 <= angle < 5*PI/4 => ret = 4 * M_SQRT1_2 - sin(angle) 3: 5*PI/4 <= angle < 7*PI/4 => ret = 6 * M_SQRT1_2 + cos(angle) 4: 7*PI/4 <= angle < 2*PI => ret = 8 * M_SQRT1_2 + sin(angle)

Examples

test_angle.c.

Definition at line 505 of file geometry.h.

sq_len_diff_vec()

static double sq_len_diff_vec ( double const a[3], double const b[3] )

inlinestatic

computes square of the lenght of the vector ab

Definition at line 249 of file geometry.h.

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sub_angles()

static int sub_angles ( struct sin_cos_angle a, struct sin_cos_angle b, struct sin_cos_angle *restrict sub )

inlinestatic

computes (a-b), if (a-b) <= 0, the result is (a-b+2*PI) a and be have to be in the range [0;2*PI[

Returns

1 if (a-b) < 0

Examples

test_angle.c, test_cell_bnd_circle.c, and test_geometry.c.

Definition at line 558 of file geometry.h.

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sub_angles_no_check()

static struct sin_cos_angle sub_angles_no_check ( struct sin_cos_angle a, struct sin_cos_angle b )

inlinestatic

computes (a-b), if (a-b) < 0, the result is (a-b+2*PI) a and be have to be in the range [0;2*PI[

Definition at line 548 of file geometry.h.

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sum_angles()

static int sum_angles ( struct sin_cos_angle a, struct sin_cos_angle b, struct sin_cos_angle *restrict sum )

inlinestatic

computes (a+b), if (a+b) >= 2*PI, the result is (a+b-2*PI) a and be have to be in the range [0;2*PI[

Returns

1 if (a+b) is >= 2*PI

Examples

test_angle.c.

Definition at line 534 of file geometry.h.

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sum_angles_no_check()

static struct sin_cos_angle sum_angles_no_check ( struct sin_cos_angle a, struct sin_cos_angle b )

inlinestatic

computes (a+b), if (a+b) >= 2*PI, the result is (a+b-2*PI) a and be have to be in the range [0;2*PI[

Examples

test_cell_bnd_circle.c.

Definition at line 524 of file geometry.h.

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XYZtoLL()

static void XYZtoLL ( double const p_in[], double * lon, double * lat )

inlinestatic

converts lon-lat coordinates into xyz ones

Further information: http://en.wikipedia.org/wiki/List_of_common_coordinate_transformations

Parameters

[in]	p_in	xyz coordinates
[out]	lon	longitude coordinate in radian
[out]	lat	latitude coordinate in radian

Examples

test_area.c, test_clipping.c, test_compute_overlap_area.c, test_lat_clipping.c, test_loncxlatc.c, test_partial_areas.c, and test_vtk_output.c.

Definition at line 318 of file geometry.h.

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yac_circle_intersect()

int yac_circle_intersect	(	struct yac_circle	a,
		struct yac_circle	b,
		double	p[3],
		double	q[3] )

Examples

test_circle.c.

Definition at line 270 of file intersection.c.

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yac_compute_bnd_triangle()

void yac_compute_bnd_triangle	(	double *	vertices,
		size_t	num_vertices,
		double	triangle[][3],
		size_t	num_tests )

computes a spherical triangle that contains all given vertices, the algorithm tries to minimise the size of the triangle

Parameters

[in]	vertices	vertices that are supposed to be within the triangle
[in]	num_vertices	number of vertices in vertices
[out]	triangle	bounding triangle
[in]	num_tests	with increasing number of tests computation time and chance of smaller bounding triangle increases

Remarks

num_tests has to be > 0

Definition at line 99 of file bnd_triangle.c.

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yac_extents_overlap()

int yac_extents_overlap	(	struct bounding_circle *	extent_a,
		struct bounding_circle *	extent_b )

checks whether two extents overlap

Parameters

[in]	extent_a	bounding circle
[in]	extent_b	bounding circle

Returns

0 if the bounding circles do not overlap

Definition at line 204 of file bnd_circle.c.

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yac_get_cell_bounding_circle()

void yac_get_cell_bounding_circle	(	struct yac_grid_cell	cell,
		struct bounding_circle *	bnd_circle )

gets the bounding circle for a grid cell

Parameters

[in]	cell	grid cell (coordinates have to be in radian)
[out]	bnd_circle	bounding circle of the grid cell

Definition at line 160 of file bnd_circle.c.

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yac_get_cell_bounding_circle_reg_quad()

void yac_get_cell_bounding_circle_reg_quad	(	double	a[3],
		double	b[3],
		double	c[3],
		struct bounding_circle *	bnd_circle )

computes the smallest bounding circle for a triangle on the sphere

Parameters

[in]	a	coordinates of first point (xyz)
[in]	b	coordinates of second point (xyz)
[in]	c	coordinates of thrid point (xyz)
[out]	bnd_circle	bounding circle

Remarks

it is assumed that all edges of the quad are either circles of longitude or latitude

Definition at line 36 of file bnd_circle.c.

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yac_get_cell_bounding_circle_unstruct_triangle()

void yac_get_cell_bounding_circle_unstruct_triangle	(	double	a[3],
		double	b[3],
		double	c[3],
		struct bounding_circle *	bnd_circle )

computes the smallest bounding circle for a triangle on the sphere

Parameters

[in]	a	coordinates of first point (xyz)
[in]	b	coordinates of second point (xyz)
[in]	c	coordinates of thrid point (xyz)
[out]	bnd_circle	bounding circle

Remarks

it is assumed that all three edges of the triangle are great circles

Definition at line 93 of file bnd_circle.c.

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yac_get_cell_circumscribe_circle_reg_quad()

void yac_get_cell_circumscribe_circle_reg_quad	(	double	a[3],
		double	b[3],
		double	c[3],
		struct bounding_circle *	bnd_circle )

computes the circumscribe circle for a quad on the sphere

Parameters

[in]	a	coordinates of first point (xyz)
[in]	b	coordinates of second point (xyz)
[in]	c	coordinates of thrid point (xyz)
[out]	bnd_circle	circumscribe circle

Remarks

it is assumed that all edges of the quad are either circles of longitude or latitude

Definition at line 27 of file bnd_circle.c.

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yac_get_cell_circumscribe_circle_unstruct_triangle()

void yac_get_cell_circumscribe_circle_unstruct_triangle	(	double	a[3],
		double	b[3],
		double	c[3],
		struct bounding_circle *	bnd_circle )

computes the circumscribe circle for a triangle on the sphere

Parameters

[in]	a	coordinates of first point (xyz)
[in]	b	coordinates of second point (xyz)
[in]	c	coordinates of thrid point (xyz)
[out]	bnd_circle	circumscribe circle

Remarks

it is assumed that all three edges of the triangle are great circles

Definition at line 45 of file bnd_circle.c.

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yac_intersect_vec()

int yac_intersect_vec	(	enum yac_edge_type	edge_type_a,
		double const	a[3],
		double const	b[3],
		enum yac_edge_type	edge_type_b,
		double const	c[3],
		double const	d[3],
		double	p[3],
		double	q[3] )

computes the intersection points of two edges

Parameters

[in]	edge_type_a	type of edge a
[in]	a	first point of edge a
[in]	b	second point of edge a
[in]	edge_type_b	type of edge b
[in]	c	first point of edge b
[in]	d	second point of edge b
[out]	p	first intersection point
[out]	q	second intersection point

Returns

0 if the intersection points are neither on edge a or b
-1 if the two circles do not intersect
1st bit will be set if p is on edge a
2nd bit will be set if q is on edge a
3rd bit will be set if p is on edge b
4th bit will be set if q is on edge b
5th bit will be set if both circles are identically

Remarks

if -1 is returned neither p or q is set

if the two circles only have one intersection point, p and q will be identically, but only the p bits will be set

Examples

test_gcxlatc.c.

Definition at line 786 of file intersection.c.

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yac_point_in_bounding_circle_vec()

static int yac_point_in_bounding_circle_vec ( double point_vector[3], struct bounding_circle * bnd_circle )

inlinestatic

checks whether a point is within a bounding circle

Parameters

[in]	point_vector	point to be checked
[in]	bnd_circle	bounding circle

Returns

0 if point is not within the bounding circle

Examples

test_bnd_sphere_part.c.

Definition at line 266 of file geometry.h.

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yac_point_in_cell()

int yac_point_in_cell	(	double	point_coords[3],
		struct yac_grid_cell	cell )

checks whether a given point is within a given cell

Parameters

[in]	point_coords
[in]	cell

Returns

0 if the point is not in the cell

Definition at line 465 of file check_overlap.c.

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yac_point_in_cell2()

int yac_point_in_cell2	(	double	point_coords[3],
		struct yac_grid_cell	cell,
		struct bounding_circle	bnd_circle )

checks whether a given point is within a given cell

Parameters

[in]	point_coords
[in]	cell
[in]	bnd_circle

Returns

0 if the point is not in the cell

Definition at line 474 of file check_overlap.c.

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yac_point_on_edge()

int yac_point_on_edge	(	double	p[3],
		double const	a[3],
		double const	b[3],
		enum yac_circle_type	circle_type )

Examples

test_clipping.c.

Definition at line 883 of file intersection.c.

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yac_triangulate_cell()

void yac_triangulate_cell	(	struct yac_grid_cell	cell,
		size_t	start_corner,
		struct yac_grid_cell *	triangles )

splits given cell into triangles

Parameters

[in]	cell	cell to be triangulated
[in]	start_corner	start algorithm at corner with this index (0 <= start_corner < n; with n being number of cell corners)
[out]	triangles	triangles that are the result of the triangulation

Remarks

the user needs to provide (n-2) initialised grid_cells for the argument triangles (n being the number of cell corners of the cell)

this routine currently only works for convex grid cells

the algorithm ignores that actual edge types for cells with more than 3 corners and assumes them to be great circle edges

Examples

test_basic_grid_data.c.

Definition at line 66 of file grid_cell.c.

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yac_triangulate_cell_indices()

void yac_triangulate_cell_indices	(	size_t const *	corner_indices,
		size_t	num_corners,
		size_t	start_corner,
		size_t(*)	triangle_indices[3] )

splits given indices of a cell into triangles

Parameters

[in]	corner_indices	cell corner indices to be triangulated
[in]	num_corners	number of corners of the cell
[in]	start_corner	start algorithm at corner with this index (0 <= start_corner < n; with n being number of cell corners)
[out]	triangle_indices	triangle indices that are the result of the triangulation

Remarks

the user needs to provide provide an array of size 3*(num_corners-2) for the argument triangle_indices

Examples

test_basic_grid_data.c.

Definition at line 144 of file grid_cell.c.

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Variable Documentation

SIN_COS_7_M_PI_4

const struct sin_cos_angle SIN_COS_7_M_PI_4 = {-0.707106781186547524401, +0.707106781186547524401}

static

Definition at line 50 of file geometry.h.

SIN_COS_LOW_TOL

const struct sin_cos_angle SIN_COS_LOW_TOL = {yac_angle_low_tol, yac_cos_angle_low_tol}

static

Examples

test_geometry.c.

Definition at line 46 of file geometry.h.

SIN_COS_M_PI

const struct sin_cos_angle SIN_COS_M_PI = {0.0, -1.0}

static

Examples

test_angle.c, test_cell_bnd_circle.c, test_geometry.c, and test_point_sphere_part.c.

Definition at line 49 of file geometry.h.

SIN_COS_M_PI_2

const struct sin_cos_angle SIN_COS_M_PI_2 = {1.0, 0.0}

static

Examples

test_bnd_sphere_part.c.

Definition at line 48 of file geometry.h.

SIN_COS_TOL

const struct sin_cos_angle SIN_COS_TOL = {yac_angle_tol, yac_cos_angle_tol}

static

Examples

test_cell_bnd_circle.c.

Definition at line 45 of file geometry.h.

SIN_COS_ZERO

const struct sin_cos_angle SIN_COS_ZERO = {0.0, 1.0}

static

Examples

test_bnd_sphere_part.c.

Definition at line 44 of file geometry.h.