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Hi,
Function can be improved by adding the normals to the triangles making up the STL surface. It only uses 0,0,0.
Surface normals are used by software that uses STL files to determine which is the front and back orientation. They can also be used with a trick to help calculate the area of a triangulated STL surface.
Here is adjusted cpp file. Input is a matrix with now four instead of three rows per triangle. First row is normal of face, followed by original three rows of coordinates of corners.
MathCad can calculate these normals and adjust the matrix before submission to the writeSTL function.
>>>>>>>>>>>>>
// WriteSTL.cpp : Defines the exported functions for the DLL application.
//
#include "StdAfx.h"roes
#include "mcadincl.h"
#include <stdio.h>
LRESULT WriteSTLFunction( LPCOMPLEXSCALAR result,
LPMCSTRING filename,
LPCOMPLEXARRAY mat );
FUNCTIONINFO WriteSTL =
{
"WriteSTL", // Name by which mathcad will recognize the function
"filename,mat", // transpose will be called as WriteSTL(filename,mat)
"returns a success" , // everything work?
(LPCFUNCTION)WriteSTLFunction, // pointer to the executible code
COMPLEX_SCALAR, // the output is a result flag
2, // the function takes on 2 arguments
{ STRING, COMPLEX_ARRAY} // the input type is a complex array
};
LRESULT WriteSTLFunction( LPCOMPLEXSCALAR result,
LPMCSTRING filename,
LPCOMPLEXARRAY mat )
{
FILE *fp;
int i;
fp = fopen(filename->str,"w");
// Mathcad matrices are col x row via API, not row x col like the rest of the world
fprintf(fp,"%s\n","solid Mathcad_Surface");
for (i=0; i<mat->rows; i+=4) {
fprintf(fp,"facet normal %f %f %f\n",mat->hReal[0][i],mat->hReal[1][i],mat->hReal[2][i]));
fprintf(fp,"outer loop\n");
fprintf(fp,"vertex %f %f %f\n",mat->hReal[0][i+1],mat->hReal[1][i+1],mat->hReal[2][i+1]);
fprintf(fp,"vertex %f %f %f\n",mat->hReal[0][i+2],mat->hReal[1][i+2],mat->hReal[2][i+2]);
fprintf(fp,"vertex %f %f %f\n",mat->hReal[0][i+3],mat->hReal[1][i+3],mat->hReal[2][i+3]);
fprintf(fp,"endloop\n");
fprintf(fp,"endfacet\n");
}
fprintf(fp,"%s\n","endsolid Mathcad_Surface");
fclose(fp);
result->real = 1;
return 0; // return 0 to indicate there was no error
}
>>>>>>>>>>>>
Can provide the MathCad14 file with the small program that adds the normals but no idea how to upload a MathCad file only images of limited size and videos can be added in this web page.
Regards
