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/*
This file is part of the FElt finite element analysis package.
Copyright (C) 1993 Jason I. Gobat and Darren C. Atkinson
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/****************************************************************************
*
* File: quad_grid.c
*
***************************************************************************/
# include <math.h>
# include "allocate.h"
# include "error.h"
# include "fe.h"
# include "objects.h"
# include "mesh.h"
# include "rules.h"
/****************************************************************************
*
* Function: GenerateQuadGrid
*
* Description: a simple procedure to generate a 2-d grid of quadrilateral
* (four shape nodes) elements with all the elements running
* parallel to one of the axes.
*
****************************************************************************/
unsigned GenerateQuadGrid (grid, element, node, numelts, numnodes, bnode, belement)
Grid grid;
Element **element;
Node **node;
unsigned *numelts;
unsigned *numnodes;
unsigned bnode;
unsigned belement;
{
double (*xrule_func) ();
double (*yrule_func) ();
unsigned ne, nn;
unsigned ecount, ncount;
unsigned node1, node2, node3, node4;
unsigned i, j;
unsigned xnum,ynum;
double x_length,
y_length;
xnum = grid -> xnumber;
ynum = grid -> ynumber;
ne = xnum*ynum;
if (ne <= 0) {
error ("nothing to generate");
return 1;
}
if (grid -> definition -> shapenodes != 4) {
error ("quadrilateral grid generation requires four node elements");
return 1;
}
nn = (xnum + 1)*(ynum + 1);
/*
* allocate some memory to hold everything that we will generate
*/
if (!(*node = Allocate(Node, nn)))
Fatal ("allocation error in grid generation");
UnitOffset (*node);
for (i = 1 ; i <= nn ; i++) {
if (!((*node) [i] = CreateNode (0)))
Fatal ("allocation error in quadrilateral grid generation");
}
if (!(*element = Allocate(Element, ne)))
Fatal ("allocation error in quadrilateral grid generation");
UnitOffset (*element);
for (i = 1 ; i <= ne ; i++) {
if (!((*element) [i] = CreateElement (0, grid -> definition)))
Fatal ("allocation error in grid generation");
}
/*
* a couple of simple computations
*/
x_length = grid -> xe - grid -> xs;
y_length = grid -> ye - grid -> ys;
xrule_func = AssignRule (grid -> xrule);
yrule_func = AssignRule (grid -> yrule);
/*
* generate a grid-work of nodes for all of our elements to use
*/
ncount = 0;
for (j = 1 ; j <= ynum + 1 ; j++) {
for (i = 1 ; i <= xnum + 1 ; i++) {
ncount++;
(*node) [ncount] -> number = bnode + ncount;
(*node) [ncount] -> x = grid -> xs + xrule_func(i, xnum, x_length);
(*node) [ncount] -> y = grid -> ys + yrule_func(j, ynum, y_length);
(*node) [ncount] -> z = 0.0;
}
}
ecount = 0;
/*
* generate all the elements that run parallel to the x-axis
*/
for (j = 1 ; j <= ynum ; j++) {
for (i = 1 ; i <= xnum ; i++) {
ecount++;
(*element) [ecount] -> number = belement + ecount;
node1 = i + (j - 1)*(xnum + 1);
node2 = node1 + 1;
node4 = node1 + (xnum + 1);
node3 = node4 + 1;
(*element) [ecount] -> node [1] = (*node) [node1];
(*element) [ecount] -> node [2] = (*node) [node2];
(*element) [ecount] -> node [3] = (*node) [node3];
(*element) [ecount] -> node [4] = (*node) [node4];
}
}
*numnodes = nn;
*numelts = ne;
return 0;
}
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