OpenGL环境下PLY三维模型的读入与显示

OpenGL环境下PLY三维模型的读入与显示的源码-CSDN下载

codeblocks配置OpenGL环境-CSDN博客

问题描述

仿照PLY格式点云读取代码，实现PLY格式三角形面片模型的读取与显示。

问题分析

分析ply文件结构
ply
format ascii 1.0 {ascii/二进制，格式版本数}
comment VCGLIB generated {注释关键词说明}
element vertex 34835 {定义“vertex”（顶点）元素，在文件中有34835个}
property float x {顶点包含浮点坐标“x”，下同}
property float y
property float z
property float nx
property float ny
property float nz
element face 69666 {在文件里有69666个“face”（面片）}
property list uchar int vertex_indices
end_header {划定头部结尾}
0.006242 0.039472 0.033507 -1.34547 -4.89656 -1.80904 {顶点列表的开始}
0.007691 0.039029 0.032395 -2.35354 -5.66907 -0.381422
0.008423 0.038501 0.033018 -3.33184 -4.82115 -1.7236
…
3 0 1 2 {面片列表开始}
3 3 4 5
3 6 7 8
3 8 9 10
…

编写程序

1)获取到ply文件中顶点的个数和面片的个数

fscanf(fp, "element vertex %d\n", &g_nVerticesNumber);

j = 0;

while (strcmp(type,"element")!=0)

{

fgets(strBuff, 256, fp);

i = 0;

while(strBuff[i]!='\0'&&strBuff[i]!=' '&&strBuff[i]!='\n')

{

type[i] = strBuff[i];

i++;

}

if (bStartPropertyCount&&strcmp(type,"property")==0)

j++;

else

bStartPropertyCount = false;

type[i] = '\0';

}

sscanf(strBuff, "element face %d\n", &g_nFacesNumber);

2)接下来逐行读取点坐标和法向量，这里的J为6

//Read in the triangles

for (i=0; i<g_nVerticesNumber; i++)

{

if (j==3)

fscanf(fp, "%f %f %f", &g_vet[i].x, &g_vet[i].y, &g_vet[i].z);

else if(j==6)

fscanf(fp, "%f %f %f %f %f %f", &g_vet[i].x, &g_vet[i].y, &g_vet[i].z, &g_norm[i].x, &g_norm[i].y, &g_norm[i].z);

else if (j==7)

fscanf(fp, "%f %f %f %f %f %f %f", &g_vet[i].x, &g_vet[i].y, &g_vet[i].z, &g_color[i].x, &g_color[i].y, &g_color[i].z, &alpha);

else if (j==10)

fscanf(fp, "%f %f %f %f %f %f %f %f %f %f", &g_vet[i].x, &g_vet[i].y, &g_vet[i].z,

&g_norm[i].x, &g_norm[i].y, &g_norm[i].z,

&g_color[i].x, &g_color[i].y, &g_color[i].z, &alpha);

else

{

printf("Warning: the viewer cann't read the colors of models\n");

exit(1);

}

GetMinMax(vMin, vMax, g_vet[i]);

Normalize(g_norm[i]);

}

3)将法向量标准化

void Normalize(VERTEX3D &v)

{

double length = sqrt(v.x*v.x+v.y*v.y+v.z*v.z);

if(length!=0)

{

v.x = v.x/length;

v.y = v.y/length;

v.z = v.z/length;

}

4)通过三角形面片绘制斯坦福兔子三维模型

void DrawVertices()
{
int i;
glPointSize(2.0);
glBegin(GL_TRIANGLES);
for(i=0;i<g_nFacesNumber;i++)
{
glBegin(GL_TRIANGLES);

glNormal3f(g_norm[triPatch[i].A].x,g_norm[triPatch[i].A].y,g_norm[triPatch[i].A].z);
glNormal3f(g_norm[triPatch[i].B].x,g_norm[triPatch[i].B].y,g_norm[triPatch[i].B].z);
glNormal3f(g_norm[triPatch[i].C].x,g_norm[triPatch[i].C].y,g_norm[triPatch[i].C].z);

glColor3f(g_color[triPatch[i].A].x,g_color[triPatch[i].A].y,g_color[triPatch[i].A].z);
glColor3f(g_color[triPatch[i].B].x,g_color[triPatch[i].B].y,g_color[triPatch[i].B].z);
glColor3f(g_color[triPatch[i].C].x,g_color[triPatch[i].C].y,g_color[triPatch[i].C].z);
glVertex3f(g_vet[triPatch[i].A].x,g_vet[triPatch[i].A].y,g_vet[triPatch[i].A].z);
glVertex3f(g_vet[triPatch[i].B].x,g_vet[triPatch[i].B].y,g_vet[triPatch[i].B].z);
glVertex3f(g_vet[triPatch[i].C].x,g_vet[triPatch[i].C].y,g_vet[triPatch[i].C].z);
glEnd();
}
}

运行截图

参考代码

#include <GL/glut.h>
#include <cstdio>
#include <cmath>
//声明结构体用于处理三维点云数据
typedef struct VERTEX_3D
{float x;float y;float z;
} VERTEX3D;//三角
typedef struct _TRIANGLE
{int A;//Index of vertex 0int B;//Index of vertex 1int C;//Index of vertex 2
} TRIANGLE;VERTEX3D *g_vet;
VERTEX3D *g_norm;
VERTEX3D *g_color;TRIANGLE *triPatch;float g_rotx = 20.0f, g_roty = 30.0f, g_rotz = 0.0f;
float g_modelPos[3] = {0, 0, -15.0f};
float g_scale = 10.0f;const float g_lightPos[] = { 1.0f, 1.0f, 1.0f, 0.0f };char g_strModelName[512] = "plant.ply"; /*Problem happens when left the [512] being empty []*/
int g_nVerticesNumber;//顶点数
int g_nFacesNumber;//面数//归一化
void Normalize(VERTEX3D &v)
{double length = sqrt(v.x*v.x+v.y*v.y+v.z*v.z);if(length!=0){v.x = v.x/length;v.y = v.y/length;v.z = v.z/length;}
}//获取最小最大值
void GetMinMax(VERTEX3D &vMin, VERTEX3D &vMax, VERTEX3D v)
{if(v.x < vMin.x ) vMin.x = v.x;if(v.y < vMin.y ) vMin.y = v.y;if(v.z < vMin.z ) vMin.z = v.z;if(v.x > vMax.x ) vMax.x = v.x;if(v.y > vMax.y ) vMax.y = v.y;if(v.z > vMax.z ) vMax.z = v.z;
}//格式化几何图形
void FormatGeometry(VERTEX3D &v, VERTEX3D vMin, VERTEX3D vMax, float scale)
{v.x = scale*(v.x - 0.5*(vMin.x + vMax.x));v.y = scale*(v.y - 0.5*(vMin.y + vMax.y));v.z = scale*(v.z - 0.5*(vMin.z + vMax.z));
}//加载网格层
void LoadMeshPLY(char *FileName)
{int i, j;VERTEX3D vMin, vMax;char strBuff[512];char type[512] = "";bool bStartPropertyCount = true;//开始属性计数float alpha;vMin.x = vMin.y = vMin.z = 99999.0;vMax.x = vMax.y = vMax.z = -99999.0;FILE* fp=fopen(FileName,"r");if (fp==NULL)//文件不存在{printf("ERROR: unable to open model [%s]!\n",FileName);exit(0);}//读文件fgets(strBuff, 256, fp);fgets(strBuff, 256, fp);fgets(strBuff, 256, fp);fscanf(fp, "element vertex %d\n", &g_nVerticesNumber);j = 0;while (strcmp(type,"element")!=0){fgets(strBuff, 256, fp);i = 0;while(strBuff[i]!='\0'&&strBuff[i]!=' '&&strBuff[i]!='\n'){type[i] = strBuff[i];i++;}if (bStartPropertyCount&&strcmp(type,"property")==0)j++;elsebStartPropertyCount = false;type[i] = '\0';}sscanf(strBuff, "element face %d\n", &g_nFacesNumber);printf("Number of Triangles: %d\n", g_nFacesNumber);fgets(strBuff, 256, fp);fgets(strBuff, 256, fp);//fgets(strBuff, 256, fp);多读的一点//Allocate the triangle arrayg_vet = new VERTEX3D[g_nVerticesNumber];g_norm = new VERTEX3D[g_nVerticesNumber];g_color = new VERTEX3D[g_nVerticesNumber];triPatch = new TRIANGLE[g_nFacesNumber];//Read in the trianglesfor (i=0; i<g_nVerticesNumber; i++){if (j==3)fscanf(fp, "%f %f %f", &g_vet[i].x, &g_vet[i].y, &g_vet[i].z);else if(j==6)fscanf(fp, "%f %f %f %f %f %f", &g_vet[i].x, &g_vet[i].y, &g_vet[i].z, &g_norm[i].x, &g_norm[i].y, &g_norm[i].z);else if (j==7)fscanf(fp, "%f %f %f %f %f %f %f", &g_vet[i].x, &g_vet[i].y, &g_vet[i].z, &g_color[i].x, &g_color[i].y, &g_color[i].z, &alpha);else if (j==10)fscanf(fp, "%f %f %f %f %f %f %f %f %f %f", &g_vet[i].x, &g_vet[i].y, &g_vet[i].z,&g_norm[i].x, &g_norm[i].y, &g_norm[i].z,&g_color[i].x, &g_color[i].y, &g_color[i].z, &alpha);else{printf("Warning: the viewer cann't read the colors of models\n");exit(1);}GetMinMax(vMin, vMax, g_vet[i]);Normalize(g_norm[i]);}int tmp;for (i=0; i<g_nFacesNumber; i++){fscanf(fp, "%d %d %d %d",&tmp , &triPatch[i].A, &triPatch[i].B, &triPatch[i].C);}if((vMax.x - vMin.x) > (vMax.y-vMin.y)){if ((vMax.x - vMin.x) > (vMax.z - vMin.z))g_scale = g_scale/(vMax.x - vMin.x);elseg_scale = g_scale/(vMax.z - vMin.z);}else{if ((vMax.y - vMin.y) > (vMax.z - vMin.z))g_scale = g_scale/(vMax.y - vMin.y);elseg_scale = g_scale/(vMax.z - vMin.z);}for (i=0; i<g_nVerticesNumber; i++)FormatGeometry(g_vet[i], vMin, vMax, g_scale);fclose(fp);
}//绘图顶点
void DrawVertices()
{int i;//glEnable(GL_LIGHTING);glPointSize(2.0);glBegin(GL_TRIANGLES);for(i=0;i<g_nFacesNumber;i++){glBegin(GL_TRIANGLES);
//glBegin();创建元素的类型，比如：点，线等。
//GL_POINTS：把每个顶点作为一个点进行处理，顶点n定义了点n，绘制N个点。
//GL_LINES：   把每个顶点作为一个独立的线段，顶点2n-1和2n之间定义了n条线段，绘制N/2条线段
//GL_LINE_STRIP：绘制从第一个顶点到最后一个顶点依次相连的一组线段，第n和n+1个顶点定义了线段n，绘制n-1条线段。
//GL_LINE_LOOP： 绘制从第一个顶点到最后一个顶点依次相连的一组线段，然后最后一个顶点和第一个顶点相连，第n和n+1个顶点定义了线段n，绘制n条线段。
//GL_TRIANGLES： 把每个顶点作为一个独立的三角形，顶点3n-2，3n-1和3n定义了第n个三角形，绘制了N/3个三角形。
//GL_TRIANGLE_STPIP：绘制一组相连的三角形，对于奇数n，顶点n，n+1，和n+2定义了第n个三角形；对于偶数n，顶点n+1，n和n+2定义了第n个三角形，绘制N-2个三角 形。
//GL_QUADS: 绘制由四个顶点组成的一组单独的四边形。顶点4n-3，4n-2，4n-1和4n定义了第n个四边形。绘制了N/4个四边形。
//GL_QUAD_STRIP：绘制一组相连的四边形。每个四边形是由一对顶点及其后给定的一对顶点共同确定的。顶点2n-1，2n，2n+2和2n+1定义了第n个四边形，绘制了N/2-1个   四边形。
//GL_POLYGON：      绘制了一个凸多边形。顶点1到n定义了这个多边形。glNormal3f(g_norm[triPatch[i].A].x,g_norm[triPatch[i].A].y,g_norm[triPatch[i].A].z);glNormal3f(g_norm[triPatch[i].B].x,g_norm[triPatch[i].B].y,g_norm[triPatch[i].B].z);glNormal3f(g_norm[triPatch[i].C].x,g_norm[triPatch[i].C].y,g_norm[triPatch[i].C].z);glColor3f(g_color[triPatch[i].A].x,g_color[triPatch[i].A].y,g_color[triPatch[i].A].z);glColor3f(g_color[triPatch[i].B].x,g_color[triPatch[i].B].y,g_color[triPatch[i].B].z);glColor3f(g_color[triPatch[i].C].x,g_color[triPatch[i].C].y,g_color[triPatch[i].C].z);glVertex3f(g_vet[triPatch[i].A].x,g_vet[triPatch[i].A].y,g_vet[triPatch[i].A].z);glVertex3f(g_vet[triPatch[i].B].x,g_vet[triPatch[i].B].y,g_vet[triPatch[i].B].z);glVertex3f(g_vet[triPatch[i].C].x,g_vet[triPatch[i].C].y,g_vet[triPatch[i].C].z);glEnd();}//glEnd();
}static void resize(int width, int height)
{const float ar = (float) width / (float) height;glViewport(0, 0, width, height);//0,0指定了窗口的左下角位置。//width,height表示视口矩形的宽度和高度，根据窗口的实时变化重绘窗口。glMatrixMode(GL_PROJECTION);//将当前矩阵指定为投影矩阵glLoadIdentity();//把矩阵设为单位矩阵gluPerspective(45, ar, 1.0, 100.0);//指定要观察的视景体在世界坐标系中的具体大小glMatrixMode(GL_MODELVIEW);//指定当前要操作的矩阵， GL_MODELVIEW模型视图glLoadIdentity() ;
}static void display(void)
{glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);glLoadIdentity() ;glTranslatef(g_modelPos[0], g_modelPos[1], g_modelPos[2]);//定义一个平移矩阵，该矩阵与当前矩阵相乘，使后续的图形相对与当前所在的屏幕位置。进行平移变换。glRotatef(g_rotx, 1.0, 0.0, 0.0);glRotatef(g_roty, 0.0, 1.0, 0.0);glRotatef(g_rotz, 0.0, 0.0, 1.0);DrawVertices();glutSwapBuffers();
}static void key(unsigned char key, int x, int y)
{switch (key){case 27 ://ASCLL表'ESC'exit(0);break;case 'w':g_rotx += 5;break;case 's':g_rotx -= 5;break;case 'a':g_roty += 5;break;case 'd':g_roty -= 5;break;case 'q':g_rotz += 5;break;case 'e':g_rotz -= 5;break;case 'z':g_modelPos[2] += 1;break;case 'x':g_modelPos[2] -= 1;break;}glutPostRedisplay();//重绘图像，否则图像只有响应鼠标或键盘消息时才会更新图像。
}static void idle(void)
{glutPostRedisplay();
}int main(int argc, char *argv[])
{glutInit(&argc, argv);//初始化GLUTglutInitWindowSize(640,480);//定义窗口大小glutInitWindowPosition(10,10);//定义窗口位置glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);printf("Tips: use 'w', 's', 'a', 'd', 'z', 'x', 'q', 'e' keys to control the model\n");if(argc<2){printf("Input the file name (without postfix e.g. .ply) of points:");scanf("%s", g_strModelName);strcat(g_strModelName, ".ply");}else{printf("%s\n", argv[1]);strcpy(g_strModelName, argv[1]);}glutCreateWindow("PLY Model Viewer");//创建窗口("窗口标题")glutReshapeFunc(resize);//自适应屏幕窗口大小的改变glutDisplayFunc(display);glutKeyboardFunc(key);glutIdleFunc(idle);glClearColor(0.2, 0.55,1.0,1);//设置好清除颜色glDisable(GL_CULL_FACE);glEnable(GL_DEPTH_TEST);glDepthFunc(GL_LESS);glEnable(GL_LIGHT0);glEnable(GL_LIGHTING);glLightfv(GL_LIGHT0, GL_POSITION, g_lightPos);glShadeModel(GL_SMOOTH);printf("Loading \"%s\"...\n", g_strModelName);LoadMeshPLY(g_strModelName);glutMainLoop();//使程序进入事件处理循环。该函数必须是main主函数的最后一条语句。return EXIT_SUCCESS;
}