Ply 形式のファイルを STL 形式に変換

変換したいだけならば、meshlab を利用するのが楽． Color STL 形式を作りたいと思い、プログラムを作成．

STL ファイルの情報: https://orion.math.iastate.edu/burkardt/data/stl/stl.html

コンパイル手順

gcc -o a.out a.cc -lm

使用法

Ply ファイルの準備
60 Excellent Free 3D Model Websites http://www.hongkiat.com/blog/60-excellent-free-3d-model-websites/
meshlab を用いて前処理
1. meshlab を起動．
2. Import Mesh でファイルを読み込む
3. Export Mesh As で ply 形式を選ぶ．normal にチェックする．binary のチェックを外す．
次のような形式に変換

その後、下のプログラムを利用．

ソースコード

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>

static void Error(char* msg)
{
	fputs(msg,stderr); fputc('\n',stderr); exit(1);
}

#define STR_LEN	256

static char	line[STR_LEN];

static void	Scan(FILE* file)
{
	char	str[STR_LEN];

	for (;;) {
	    if (fgets(line,STR_LEN,file)==NULL)
		Error("unexpected end of file.");

	    if (line[strlen(line)-1]!='\n') Error("missing end of line.");

	    if (sscanf(line,"%s",str)==1 && strcmp(str,"comment")) return;
	}
}

static int	CheckElement(FILE* file, char* element)
{
	char	str[3][STR_LEN];
	int	number;

	Scan(file);
	fprintf(stderr, "%s\n", line); 
	if (sscanf(line,"%s %s %s",str[0],str[1],str[2])!=3 ||
	    strcmp(str[0],"element") ||
	    strcmp(str[1],element) ||
	    sscanf(str[2],"%d",&number)!=1 ||
	    number<=0) {
	  fprintf(stderr,"bad element specification for %s (number = %d) \n",element, number);
	    exit(1);
	}
	return number;
}

static void	CheckProperty(FILE* file, char* type, char* name, char* element)
{
	char	str[3][STR_LEN];

	Scan(file);
	if (sscanf(line,"%s %s %s",str[0],str[1],str[2])!=3 ||
	    strcmp(str[0],"property") ||
	    strcmp(str[1],type) ||
	    strcmp(str[2],name)) {
	  fprintf(stderr,"bad property specification for %s, (line = %s)\n",element, line);
	    exit(1);
	}
}

#define MA(noe,ptr)	malloc((noe)*sizeof(*(ptr)))

typedef struct _vertex {
  double x;  
  double y;  
  double z;  
  double nx;
  double ny;
  double nz;
  int r;
  int g; 
  int b;
  int alpha;
} vertex; 

typedef struct _face {
  int v0; 
  int v1; 
  int v2; 
} face; 

int	main(int argc, char** argv)
{
	FILE	*zcp,*stl;
	char	str[10][STR_LEN];
	int vertices, faces;
	//	int	vertices,faces,face,vertex,idx,R,G,B;
	//	double	x10,x20,y10,y20,z10,z20,nx,ny,nz,n;
	//	short	flag;

	if (argc!=3) Error("usage : zcp_stl ZCP STL");

	if (argv[1][0]=='-')
	    zcp=stdin;
	else
	    if ((zcp=fopen(argv[1],"rb"))==NULL) Error("file not found.");

	if (fgetc(zcp)!='p' ||
	    fgetc(zcp)!='l' ||
	    fgetc(zcp)!='y') Error("bad magic number.");

	Scan(zcp);
	if (sscanf(line,"%s %s %s",str[0],str[1],str[2])!=3 ||
	    strcmp(str[0],"format") ||
	    //	    strcmp(str[1],"binary_little_endian") ||
	    strcmp(str[1],"ascii") ||
	    strcmp(str[2],"1.0"))
	    Error("bad format specification.");

	vertices=CheckElement(zcp,"vertex");

	CheckProperty(zcp,"float","x","vertex");
	CheckProperty(zcp,"float","y","vertex");
	CheckProperty(zcp,"float","z","vertex");

	CheckProperty(zcp,"float","nx","vertex");
	CheckProperty(zcp,"float","ny","vertex");
	CheckProperty(zcp,"float","nz","vertex");

	faces=CheckElement(zcp,"face");

	Scan(zcp);
	if (sscanf(line,"%s %s %s %s %s",
			str[0],str[1],str[2],str[3],str[4])!=5 ||
	    strcmp(str[0],"property") ||
	    strcmp(str[1],"list") ||
	    strcmp(str[2],"uchar") ||
	    strcmp(str[3],"int") ||
	    strcmp(str[4],"vertex_indices"))
	    Error("bad vertex index specification for face.");

	CheckProperty(zcp,"uchar","red","vertex");
	CheckProperty(zcp,"uchar","green","vertex");
	CheckProperty(zcp,"uchar","blue","vertex");
	CheckProperty(zcp,"uchar","alpha","vertex");

	Scan(zcp);
	if (sscanf(line,"%s",str[0])!=1 ||
	    strcmp(str[0],"end_header")) Error("missing end of header.");

	vertex *XYZ = (vertex *)malloc(sizeof(vertex) * vertices); 

	int i;
	for (i=0; i<vertices; i++) {
	  Scan(zcp);
	  sscanf(line,"%s %s %s %s %s", str[0], str[1], str[2], str[3], str[4], str[5], str[6], str[7], str[8], str[9] );   
	  XYZ[i].x = atof(str[0]);
	  XYZ[i].y = atof(str[1]);
	  XYZ[i].z = atof(str[2]);

	  XYZ[i].nx = atof(str[3]);
	  XYZ[i].ny = atof(str[4]);
	  XYZ[i].nz = atof(str[5]);

	  XYZ[i].r = atoi(str[6]);
	  XYZ[i].g = atoi(str[7]);
	  XYZ[i].b = atoi(str[8]);
	  XYZ[i].alpha = atoi(str[9]);

	}

	face *F = (face *)malloc(sizeof(face) * faces); 

	for (i=0; i<faces; i++) {
	  Scan(zcp);
	  sscanf(line,"%s %s %s %s", str[0], str[1], str[2], str[3]);
	  F[i].v0 = atoi(str[1]);
	  F[i].v1 = atoi(str[2]);
	  F[i].v2 = atoi(str[3]);
	}
	// for debug
	// printf("%f %f %f\n", XYZ[0].x, XYZ[0].y, XYZ[0].z );
	// printf("%d %d %d\n", F[0].v0, F[0].v1, F[0].v2 );

	if (argv[2][0]=='-')
	    stl=stdout;
	else
	    if ((stl=fopen(argv[2],"w"))==NULL) Error("file not stored.");

	// header
	fputs("solid \n", stl);

	for (i=0; i<faces; i++) {
	  double x10 = XYZ[F[i].v1].x  -  XYZ[F[i].v0].x;
	  double x20 = XYZ[F[i].v2].x  -  XYZ[F[i].v0].x;
	  double y10 = XYZ[F[i].v1].y  -  XYZ[F[i].v0].y;
	  double y20 = XYZ[F[i].v2].y  -  XYZ[F[i].v0].y;
	  double z10 = XYZ[F[i].v1].z  -  XYZ[F[i].v0].z;
	  double z20 = XYZ[F[i].v2].z  -  XYZ[F[i].v0].z;
	  double nx=y10*z20-z10*y20;
	  double ny=z10*x20-x10*z20;
	  double nz=x10*y20-y10*x20; 
	  double n=sqrt(nx*nx+ny*ny+nz*nz);
	  fprintf(stl, "facet normal %f %f %f\n", nx/n, ny/n, nz/n );

	  fprintf(stl, "outer loop\n");

	  fprintf(stl, "vertex %f %f %f %d %d %d\n", XYZ[F[i].v0].x, XYZ[F[i].v0].y, XYZ[F[i].v0].z,  XYZ[F[i].v0].r, XYZ[F[i].v0].g, XYZ[F[i].v0].b );
	  fprintf(stl, "vertex %f %f %f %d %d %d\n", XYZ[F[i].v1].x, XYZ[F[i].v1].y, XYZ[F[i].v1].z,  XYZ[F[i].v1].r, XYZ[F[i].v1].g, XYZ[F[i].v1].b );
	  fprintf(stl, "vertex %f %f %f %d %d %d\n", XYZ[F[i].v2].x, XYZ[F[i].v2].y, XYZ[F[i].v2].z,  XYZ[F[i].v2].r, XYZ[F[i].v2].g, XYZ[F[i].v2].b );

	  fprintf(stl, "endloop\n");

	  fprintf(stl, "endfacet\n");
	}

	// end
	fputs("endsolid \n", stl);
	fclose(stl);
	
	//
	if ( XYZ != NULL ) {
	  free(XYZ);
	}
	if ( F != NULL ) {
	  free(F);
	}

	return 0;
}