一、ply文件简介
ply文件是一种用于描述图形结构的文件。一般包括：头部、顶点列表、面片列表、其他元素列表等。
例如下面这个ply文件描述了一个cube。
ply format ascii 1.0 comment made by anonymous comment this file is a cube element vertex 8 property float32 x property float32 y property float32 z element face 12 property list uint8 int32 vertex_index end_header 0 0 0 0 0 0.01 0 0.01 0.01 0 0.01 0 0.01 0 0 0.01 0 0.01 0.01 0.01 0.01 0.01 0.01 0 3 0 1 2 3 0 3 2 3 7 9 5 3 7 4 5 3 0 4 5 3 0 1 5 3 1 5 6 3 1 2 6 3 2 6 7 3 2 3 7 3 1 7 4 3 3 0 4
二、ply文件的解析及用openGL显示
ply的文件格式比较简单，我们只需要对其中的信息进行提取，在调用openGL中相应的函数就可以实现显示ply模型了。
代码：
1 #ifndef PLYREADER_H_
2 #define PLYREADER_H_
3
4 #include <GL/glut.h>
5 #include <GL/glu.h>
6 #include <GL/gl.h>
7 #include <vector>
8 using namespace std;
9
10 struct SModelData
11 {
12 vector <float> vecFaceTriangles; // = face * 9
13 vector <float> vecFaceTriangleColors; // = face * 9
14 int iTotalConnectedTriangles;
15 };
16
17 class CPLYLoader
18 {
19 public:
20 CPLYLoader();
21 bool LoadModel(char * filename);
22 void Draw();
23 private:
24 float * mp_vertexXYZ;
25 float * mp_vertexRGB;
26 int m_totalConnectedQuads;
27 int m_totalConnectedPoints;
28 int m_totalFaces;
29 SModelData m_ModelData;
30 };
31
32 #endif
1 #include "stdafx.h"
2 #include "PLYLoader.h"
3
4 CPLYLoader::CPLYLoader()
5 {
6 this->m_totalConnectedQuads = 0;
7 this->m_totalConnectedPoints = 0;
8 this->m_ModelData.iTotalConnectedTriangles = 0;
9 }
10
11 bool CPLYLoader::LoadModel(char * filename)
12 {
13 printf("Loading %s...\n", filename);
14 char * pch = strstr(filename, ".ply");
15 if (pch != NULL)
16 {
17 FILE * file = fopen(filename, "r");
18 if (!file)
19 {
20 printf("load PLY file %s failed\n", filename);
21 return false;
22 }
23 fseek(file, 0, SEEK_END);
24 long fileSize = ftell(file);
25 try
26 {
27 mp_vertexXYZ = (float*)malloc(fileSize);
28 mp_vertexRGB = (float*)malloc(fileSize);
29 }
30 catch (char *)
31 {
32 return false;
33 }
34 if (mp_vertexXYZ == NULL || mp_vertexRGB == NULL) return false;
35 fseek(file, 0, SEEK_SET);
36 if (file)
37 {
38 char buffer[1000];
39 fgets(buffer, 300, file);
40 //READ HEADER
41 while (strncmp("element vertex", buffer, strlen("element vertex")) != 0)
42 {
43 fgets(buffer, 300, file);
44 }
45 strcpy(buffer, buffer + strlen("element vertex"));
46 sscanf(buffer, "%i", &this->m_totalConnectedPoints);
47 printf("first we get %d vertexs\n", this->m_totalConnectedPoints);
48 //Find the number of vertexes
49 fseek(file, 0, SEEK_SET);
50 while (strncmp("element face", buffer, strlen("element face")) != 0)
51 {
52 fgets(buffer, 300, file);
53 }
54 strcpy(buffer, buffer + strlen("element face"));
55 sscanf(buffer, "%i", &this->m_totalFaces);
56 printf("second we get %d faces\n", this->m_totalFaces);
57 //Go to end_header
58 while (strncmp("end_header", buffer, strlen("end_header")) != 0)
59 {
60 fgets(buffer, 300, file);
61 }
62 //Read vertices
63 int i = 0;
64 for (int iterator = 0; iterator < this->m_totalConnectedPoints; iterator++)
65 {
66 fgets(buffer, 300, file);
67 sscanf(buffer, "%f %f %f", &mp_vertexXYZ[i], &mp_vertexXYZ[i + 1], &mp_vertexXYZ[i + 2]);
68 i += 3;
69 }
70 //Read faces
71 for (int iterator = 0; iterator < this->m_totalFaces; iterator++)
72 {
73 fgets(buffer, 300, file);
74 //Triangular patch
75 if (buffer[0] == '3')
76 {
77 int vertex1 = 0, vertex2 = 0, vertex3 = 0;
78 buffer[0] = ' ';
79 sscanf(buffer, "%i%i%i", &vertex1, &vertex2, &vertex3);
80 //point
81 m_ModelData.vecFaceTriangles.push_back(mp_vertexXYZ[3 * vertex1]);
82 m_ModelData.vecFaceTriangles.push_back(mp_vertexXYZ[3 * vertex1 + 1]);
83 m_ModelData.vecFaceTriangles.push_back(mp_vertexXYZ[3 * vertex1 + 2]);
84 m_ModelData.vecFaceTriangles.push_back(mp_vertexXYZ[3 * vertex2]);
85 m_ModelData.vecFaceTriangles.push_back(mp_vertexXYZ[3 * vertex2 + 1]);
86 m_ModelData.vecFaceTriangles.push_back(mp_vertexXYZ[3 * vertex2 + 2]);
87 m_ModelData.vecFaceTriangles.push_back(mp_vertexXYZ[3 * vertex3]);
88 m_ModelData.vecFaceTriangles.push_back(mp_vertexXYZ[3 * vertex3 + 1]);
89 m_ModelData.vecFaceTriangles.push_back(mp_vertexXYZ[3 * vertex3 + 2]);
90 //color
91 m_ModelData.vecFaceTriangleColors.push_back(1.0);
92 m_ModelData.vecFaceTriangleColors.push_back(1.0);
93 m_ModelData.vecFaceTriangleColors.push_back(1.0);
94 m_ModelData.vecFaceTriangleColors.push_back(1.0);
95 m_ModelData.vecFaceTriangleColors.push_back(1.0);
96 m_ModelData.vecFaceTriangleColors.push_back(1.0);
97 m_ModelData.vecFaceTriangleColors.push_back(1.0);
98 m_ModelData.vecFaceTriangleColors.push_back(1.0);
99 m_ModelData.vecFaceTriangleColors.push_back(1.0);
100 m_ModelData.iTotalConnectedTriangles += 3;
101 }
102 }
103 fclose(file);
104 printf("%s Loaded!\n", filename);
105 return true;
106 }
107 else
108 {
109 printf("File can't be opened\n");
110 return false;
111 }
112 }
113 else
114 {
115 printf("File does not have a ply extension.\n");
116 return false;
117 }
118 }
119
120 void CPLYLoader::Draw() //implemented in GLPainter, not called again
121 {
122 glVertexPointer(3, GL_FLOAT, 0, m_ModelData.vecFaceTriangles.data());
123 glColorPointer(3, GL_FLOAT, 0, m_ModelData.vecFaceTriangleColors.data());
124 glDrawArrays(GL_TRIANGLES, 0, m_ModelData.iTotalConnectedTriangles);
125 }
1 #include "stdafx.h"
2 #include "PlyLoader.h"
3 #include <gl/glut.h>
4
5 CPLYLoader plyLoader;
6
7 void init()
8 {
9 glClearColor(0, 0, 0, 0);
10 glEnableClientState(GL_VERTEX_ARRAY);
11 glEnable(GL_COLOR_ARRAY);
12 plyLoader.LoadModel("dragon.ply");
13 }
14
15 void display()
16 {
17 glClear(GL_COLOR_BUFFER_BIT);
18 plyLoader.Draw();
19 glFlush();
20 }
21
22 int _tmain(int argc, _TCHAR* argv[])
23 {
24 glutInit(&argc, (char **)argv);
25 glutInitWindowSize(500, 500);
26 glutInitWindowPosition(100, 100);
27 glutCreateWindow("load model");
28 init();
29 glutDisplayFunc(display);
30 glutMainLoop();
31 return 0;
32 }