Triangular geometry

Hallo everybody! I need your help in the following problem: I want to write a C++ programm for a 3D triangular geometry.It's my first time dealing with C++ and i find some difficulties. I found a code for a 2d triangular geometry so i need to make some changes for the 3d case. Can anybody help me with this??? I'm sending you the code i found.D The code is: /* ---------------------------------------------------------------------- 2d triangle ------------------------------------------------------------------------- */

#include "stdlib.h" #include "string.h" #include "region_triangle.h" #include "error.h"

using namespace LAMMPS_NS;

#define MIN(a,b) ((a) < (b) ? (a) : (b)) #define MAX(a,b) ((a) > (b) ? (a) : (b))

/* ---------------------------------------------------------------------- */

RegTriangle::RegTriangle(LAMMPS *lmp, int narg, char **arg) : Region(lmp, narg, arg) { options(narg-8,&arg[8]);

x1 = xscale*atof(arg[2]); y1 = yscale*atof(arg[3]); x2 = xscale*atof(arg[4]); y2 = yscale*atof(arg[5]); x3 = xscale*atof(arg[6]); y3 = yscale*atof(arg[7]);

// extent of 2d triangle

extent_xlo = MIN(x1,x2); extent_xlo = MIN(extent_xlo,x3); extent_xhi = MAX(x1,x2); extent_xhi = MAX(extent_xhi,x3);

extent_ylo = MIN(y1,y2); extent_ylo = MIN(extent_ylo,y3); extent_yhi = MAX(y1,y2); extent_yhi = MAX(extent_yhi,y3);

extent_zlo = -0.5; extent_zhi = 0.5; }

/* ---------------------------------------------------------------------- */

int RegTriangle::match(double x, double y, double z) { double side1 = (x-x1)*(y2-y1) - (y-y1)*(x2-x1); double side2 = (x-x2)*(y3-y2) - (y-y2)*(x3-x2); double side3 = (x-x3)*(y1-y3) - (y-y3)*(x1-x3);

int inside; if (side1 > 0.0 && side2 > 0.0 && side3 > 0.0) inside = 1; else inside = 0;

return !(inside ^ interior); // 1 if same, 0 if different }

Thank u very much in advance. Waiting for your reply.

What exactly do you want in 3D?

The 2d code you've given seems to be mostly concerned with seeing if one triangle matches another.

Dear sharma, Thank u very much for your answer. I want to write a code which will draw a 3D triangular region by giving the point's coordinates as input.Thanks in advance for your answer.D

What platform are you working on.

When you say draw, I assume you want something to appear on the screen. I assume also that when you're talking about 3D you mean you want to draw something like a pyramid, with 4 or perhaps 5 corners.

Next are you trying to make a solid shape, or just the outline. Once you're decided how you're going to display this stuff, then putting the data together is fairly simple. As a start consider http://www.codersource.net/mfc_tutorial_Part3.html