gs_norms.c File Reference

OGSF library - calculation normals (lower level functions) More...

#include <math.h>
#include <grass/gis.h>
#include <grass/ogsf.h>
#include "gsget.h"
#include "rowcol.h"

Include dependency graph for gs_norms.c:

Go to the source code of this file.

Macros
#define	NTOP   0x00001000
#define	NBOT   0x00000100
#define	NLFT   0x00000010
#define	NRGT   0x00000001
#define	NALL   0x00001111
#define	NTL   0x00001010
#define	NTR   0x00001001
#define	NBL   0x00000110
#define	NBR   0x00000101
#define	SET_NORM(i)
	This macro is only used in the function calc_norm()

Functions
void	init_vars (geosurf *gs)
	Init variables.
int	gs_calc_normals (geosurf *gs)
	Calculate normals.
int	calc_norm (geosurf *gs, int drow, int dcol, unsigned int neighbors)
	Calculate normals.

Detailed Description

OGSF library - calculation normals (lower level functions)

GRASS OpenGL gsurf OGSF Library

SPDX-FileCopyrightText: 1999-2008 GRASS Development Team SPDX-License-Identifier: GPL-2.0-or-later

Author

Bill Brown USACERL

Doxygenized by Martin Landa <landa.martin gmail.com> (May 2008)

Definition in file gs_norms.c.

Macro Definition Documentation

NALL

#define NALL   0x00001111

Definition at line 28 of file gs_norms.c.

NBL

#define NBL   0x00000110

Definition at line 32 of file gs_norms.c.

NBOT

#define NBOT   0x00000100

Definition at line 24 of file gs_norms.c.

NBR

#define NBR   0x00000101

Definition at line 33 of file gs_norms.c.

NLFT

#define NLFT   0x00000010

Definition at line 25 of file gs_norms.c.

NRGT

#define NRGT   0x00000001

Definition at line 26 of file gs_norms.c.

NTL

#define NTL   0x00001010

Definition at line 30 of file gs_norms.c.

NTOP

#define NTOP   0x00001000

Definition at line 23 of file gs_norms.c.

NTR

#define NTR   0x00001001

Definition at line 31 of file gs_norms.c.

SET_NORM

#define SET_NORM

(

i

)

Value:

    dz1 = z1 - z2;                                                      \
    dz2 = z3 - z4;                                                      \
    temp[0] = (float)-dz1 * y_res_z2;                                   \
    temp[1] = (float)dz2 * x_res_z2;                                    \
    temp[2] = c_z2;                                                     \
    normalizer = sqrt(temp[0] * temp[0] + temp[1] * temp[1] + c_z2_sq); \
    if (!normalizer)                                                    \
        normalizer = 1.0;                                               \
    temp[X] /= normalizer;                                              \
    temp[Y] /= normalizer;                                              \
    temp[Z] /= normalizer;                                              \
    PNORM(i, temp);

This macro is only used in the function calc_norm()

Definition at line 38 of file gs_norms.c.

Function Documentation

calc_norm()

int calc_norm	(	geosurf *	gs,
		int	drow,
		int	dcol,
		unsigned int	neighbors
	)

Calculate normals.

Need either four neighbors or two non-linear neighbors passed initial state of neighbors known from array position and data row & col

Parameters

gs	surface (geosurf)
drow	data row
dcol	data col
neighbors	neighbors id

Returns

0 no normals

1 on success

Definition at line 202 of file gs_norms.c.

References BM_get(), DRC2OFF, GET_MAPATT, NBOT, NLFT, NRGT, NTOP, and SET_NORM.

Referenced by gs_calc_normals().

gs_calc_normals()

int gs_calc_normals

(

geosurf *

gs

)

Calculate normals.

OPTIMIZED for constant dy & dx

The norm array is always the same size, but diff resolutions force resampled data points to have their normals recalculated, then only those norms are passed to n3f during drawing. Norms are converted to a packed unsigned int for storage, must be converted back at time of use.

Todo:

fix to correctly calculate norms when mapped to sphere!

Uses the previous and next cells (when available) for normal calculations to produce smoother normals

Parameters

gs	surface (geosurf)

Returns

1 on success

0 on failure

Definition at line 120 of file gs_norms.c.

References calc_norm(), G_debug(), gs_update_curmask(), init_vars(), NALL, NBL, NBOT, NBR, NLFT, NRGT, NTL, NTOP, NTR, VCOLS, and VROWS.

Referenced by GS_get_norm_at_xy(), GS_update_normals(), gsd_coarse_surf_map(), and gsd_surf().

init_vars()

void init_vars

(

geosurf *

gs

)

Init variables.

for optimization

Parameters

gs	surface (geosurf)

Definition at line 69 of file gs_norms.c.

References ATT_TOPO, gs_get_att_typbuff(), GS_get_scale(), and GS_global_exag().

Referenced by gs_calc_normals().