OpenGL——3D Rendering Pipeline

  1 // Computer Graphics: HW3
  2 // 3D Transformation: 
  3 
  4 
  5 #include <iostream>
  6 #include <string>
  7 #include <cstdlib>
  8 #include <cmath>
  9 #include <cstdio>
 10 #include <vector>
 11 #include <gl/glut.h>
 12 #include <iomanip>
 13 #include <fstream>
 14 
 15 using namespace std;
 16 
 17 const int dimension = 4;
 18 const double PI = acos(-1);
 19 const double eps = 0.0000001;
 20 
 21 //定义向量 
 22 struct vec {
 23     float x;
 24     float y;
 25     float z;
 26     vec(float _x=0, float _y=0, float _z=0):x(_x), y(_y), z(_z){}
 27 };
 28 
 29 //向量的叉乘并化为单位向量 
 30 vec cross(vec a, vec b)
 31 {
 32     vec res;
 33     res.x = a.y * b.z - b.y * a.z;
 34     res.y = -(a.x * b.z - b.x * a.z);
 35     res.z = a.x * b.y - b.x * a.y;
 36     float l = sqrt(res.x*res.x+res.y*res.y+res.z*res.z);
 37     res.x = res.x / l;
 38     res.y = res.y / l;
 39     res.z = res.z / l;
 40     return res;
 41 }
 42 
 43 //定义多边形的点 
 44 struct poly_point {        
 45     float x;
 46     float y;
 47     float z;
 48     float w;
 49     poly_point(){ x=0; y=0; z=0; w=1;}
 50     poly_point(float _x, float _y, float _z, float _w=1){ x=_x; y=_y; z=_z; w=_w;}
 51 };
 52 
 53 //定义矩阵用作变换操作  
 54 struct mat {                    
 55     float m[4][4];
 56     mat()
 57     {
 58         memset(m,0,sizeof(m));
 59         m[0][0]=m[1][1]=m[2][2]=m[3][3]=1;        
 60     }
 61     void reset_mat()
 62     {
 63         memset(m,0,sizeof(m));
 64         m[0][0]=m[1][1]=m[2][2]=m[3][3]=1;
 65     }
 66 };
 67 
 68 //新建各种变换矩阵，初始化为单位矩阵 
 69 mat T,S,R,Rx,Ry,Rz,Sh,TM, M,GRM,EM,Mirrorx, PM, WTVM;
 70 
 71 //重载*号实现矩阵乘法
 72 mat operator * (mat a, mat b)        
 73 {
 74     mat c;
 75     memset(c.m,0,sizeof(c.m));    //注意要先初始化为0 
 76     for(int i=0; i<dimension; i++)
 77         for(int j=0; j<dimension; j++)
 78             for(int k=0; k<dimension; k++)
 79                 c.m[i][j] += (a.m[i][k]*b.m[k][j]);        
 80     return c;
 81 }
 82 
 83 //定义矩阵乘以向量 
 84 poly_point mat_mul_vec(mat t, poly_point pp)
 85 {
 86     poly_point res;
 87     res.x = t.m[0][0]*pp.x+t.m[0][1]*pp.y+t.m[0][2]*pp.z+t.m[0][3]*pp.w;
 88     res.y = t.m[1][0]*pp.x+t.m[1][1]*pp.y+t.m[1][2]*pp.z+t.m[1][3]*pp.w;
 89     res.z = t.m[2][0]*pp.x+t.m[2][1]*pp.y+t.m[2][2]*pp.z+t.m[2][3]*pp.w;
 90     res.w = t.m[3][0]*pp.x+t.m[3][1]*pp.y+t.m[3][2]*pp.z+t.m[3][3]*pp.w;
 91     return res;
 92 }
 93 //输出矩阵用作测试 
 94 void print_mat(mat M)
 95 {
 96     for(int i=0; i<dimension; i++)
 97     {
 98         for(int j=0; j<dimension; j++)
 99             printf("%.2lf ", M.m[i][j]);
100         printf("\n");
101     }
102     printf("\n");
103 }
104 
105 int num_tm=0;                                                //记录输入object的个数 
106 poly_point poly_vertex[10][2000], observe[10][2000];        //保存原来的输入的多边形的点，保存经历所有变换后的点用于输出 
107 int poly_face[4000][4];                                        //保存多边形的面用于画线 
108 string file_name;                                            //读取asc文件的文件名 
109 float VL,VR,VB,VT;                                            //viewport的坐标                 
110 float Near, Far, FOV;                                        //求PM投影矩阵用到的参数 
111 int height, width, n;                                        //n为多边形组成每个面的点的个数 
112 int num_vertex, num_face;                                    //记录输入的多边形的点的个数和面的个数 
113 void displayFunc(void);
114 void ReadInput(bool& IsExit);
115 
116 //hw3
117 void scale(float sx, float sy, float sz);                    //scale放缩变换    
118 void rotate(float rx, float ry, float rz, int i=0);            //rotate旋转变换 
119 void translate(float tx, float ty, float tz);                //translate平移变换 
120 void reset(); 
121 //获得EM和PM矩阵 
122 void observer(float PX, float PY, float PZ, float CX, float CY, float CZ, float Tilt, float Near, float Far, float FOV);
123 void view(float VL, float VR, float VB, float VT);            //获得WTVM矩阵 
124 void display();                                                //做observer和viewport变换并画点 
125 void read_asc_file();                                        //读取asc文件 
126 void transform(mat t);                                        //输入一个矩阵，对poly_vertex里的每个点做一次变换 
127 void projection(float AR, float Near, float Far, float FOV);//投影变换，即获得PM矩阵 
128 void per_div();                                                //perspective divide
129 void transform_observe(mat t);                                //对observe中的每个点进行矩阵变换 
130 void DrawWindow();                                            //画框框 
131 void print_mat(mat t);                                        //输出矩阵测试 
132 void print();                                                //输出点测试 
133 
134 //hw1中已经实现的函数 
135 void drawDot(int x, int y, float r, float g, float b);    
136 void drawLine1(int x0, int x1, int y0, int y1, bool xy_interchange);
137 void drawLine2(int x0, int x1, int y0, int y1, bool xy_interchange);
138 void drawLine3(int x0, int x1, int y0, int y1, bool xy_interchange);
139 void drawLine4(int x0, int x1, int y0, int y1, bool xy_interchange);
140 void DrawLines_4(int x1, int y1, int x2, int y2);
141 
142 void myKeyboard(unsigned char key, int x, int y) 
143 {
144     cout << "KEYYYY" << endl;
145     switch(key) {
146     // Draw dots with ‘d‘ or ‘D‘
147     case ‘q‘:
148     case ‘Q‘:
149         //glutMouseFunc(Mymouse);
150           exit(0);
151           break;
152     }
153 }
154 void ReadInput(bool& IsExit)
155 {
156     float sx,sy,sz, tx,ty,tz, rx,ry,rz;
157     float PX, PY, PZ, CX, CY, CZ, Tilt; 
158     string command,comment;
159     cin>>command;
160     if (command=="scale")
161     {
162         cout<<command<<endl;
163         cin>>sx>>sy>>sz;
164         scale(sx,sy,sz);    
165     }
166     else if (command=="rotate")
167     {
168         cout<<command<<endl;
169         cin>>rx>>ry>>rz;
170         rotate(rx,ry,rz,0);    
171     }
172     else if (command=="translate")
173     {
174         cout<<command<<endl;
175         cin>>tx>>ty>>tz;
176         translate(tx,ty,tz);    
177     }
178     else if (command=="reset")
179     {
180         cout<<command<<endl;
181         //reset();
182     }
183     else if (command=="observer")
184     {
185         cout<<command<<endl;
186         cin>>PX>>PY>>PZ>>CX>>CY>>CZ>>Tilt>>Near>>Far>>FOV;
187         observer(PX,PY,PZ,CX,CY,CZ,Tilt,Near,Far,FOV);
188     }
189     else if (command=="viewport")
190     {
191         cout<<command<<endl;
192         cin>>VL>>VR>>VB>>VT;
193         view(VL,VR,VB,VT);
194     }
195     else if (command=="end")
196     {
197         cout<<command<<endl;
198         IsExit=true;
199         //exit(0);
200     }
201     else if (command=="#")
202     {
203         getline(cin, comment);
204     }
205     else if (command=="display")
206     {
207         cout<<command<<endl;
208         display();
209     }
210     else if (command=="object")
211     {
212         cout<<command<<endl;
213         cin >> file_name;
214         read_asc_file();
215     }
216 }
217 
218 
219 // Display function
220 void displayFunc(void){
221   
222   freopen("test.in", "r", stdin);
223   bool IsExit;
224   IsExit=false;
225   // clear the entire window to the background color
226   glClear(GL_COLOR_BUFFER_BIT);
227   while (!IsExit)
228   {
229     glClearColor(0.0, 0.0, 0.0, 0.0); 
230 //    redraw();
231   // draw the contents!!! Iterate your object‘s data structure!
232   // flush the queue to actually paint the dots on the opengl window
233     glFlush();
234     ReadInput(IsExit);
235   }
236  // infile.close();
237   //exit(0);
238 }
239 
240 
241 // Main
242 void main(int ac, char** av) {
243   //initial();
244   
245   int winSizeX, winSizeY;
246   string name;
247   
248   if(ac == 3) {
249     winSizeX = atoi(av[1]);
250     winSizeY = atoi(av[2]);
251 //        cout<<"Done";
252   }
253   else { // default window size
254     winSizeX = 800;
255     winSizeY = 600;
256 
257   }
258   
259     
260 //  cout<<"Please input file name:"<<endl;
261 //  cin>>name;
262 //  infile.open(name.c_str());
263  // exit(0);
264  // infile.open("inp3.txt");
265 // infile.open(av[1]);
266   width  = winSizeX;
267   height = winSizeY;
268 
269   // initialize OpenGL utility toolkit (glut)
270   glutInit(&ac, av);
271 
272   // single disply and RGB color mapping
273   glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); // set display mode
274   glutInitWindowSize(winSizeX, winSizeY);      // set window size
275   glutInitWindowPosition(0, 0);                // set window position on screen
276   glutCreateWindow("Lab2 Window");       // set window title
277   
278   // set up the mouse and keyboard callback functions
279    // register the keyboard action function
280   glutKeyboardFunc(myKeyboard);
281   // displayFunc is called whenever there is a need to redisplay the window,
282   // e.g., when the window is exposed from under another window or when the window is de-iconified
283   glutDisplayFunc(displayFunc); // register the redraw function
284   
285   // set background color
286   glClearColor(0.0, 0.0, 0.0, 0.0);     // set the background to black
287   glClear(GL_COLOR_BUFFER_BIT); // clear the buffer
288 
289   // misc setup
290   glMatrixMode(GL_PROJECTION);  // setup coordinate system
291   glLoadIdentity();
292   gluOrtho2D(0, winSizeX, 0, winSizeY);
293   glShadeModel(GL_FLAT);
294   glFlush();
295   glutMainLoop();
296 }
297 
298 
299 void scale(float sx, float sy, float sz)
300 {
301     S.m[0][0]=sx;    S.m[1][1]=sy;    S.m[2][2]=sz;
302     TM=S*TM;
303 }
304 void rotate(float rx, float ry, float rz, int i)
305 {
306     if(i == 0)
307     {
308         rx = rx * PI / 180.0;    ry = ry * PI / 180.0;    rz = rz * PI / 180.0;
309     }
310     Rx.m[1][1]=cos(rx);    Rx.m[2][2]=cos(rx);    Rx.m[1][2]=-sin(rx);    Rx.m[2][1]=sin(rx);
311     Ry.m[0][0]=cos(ry);    Ry.m[2][2]=cos(ry);    Ry.m[0][2]=sin(ry);        Ry.m[2][0]=-sin(ry);
312     Rz.m[0][0]=cos(rz);    Rz.m[1][1]=cos(rz);    Rz.m[0][1]=-sin(rz);    Rz.m[1][0]=sin(rz);
313     R = Rz*Ry*Rz;
314     TM=R*TM;
315 }
316 void translate(float tx, float ty, float tz)
317 {
318     T.m[0][3]=tx;    T.m[1][3]=ty;    T.m[2][3]=tz;
319     TM=T*TM;
320 }
321 void reset()
322 {
323     /*T.reset_mat(),S.reset_mat(),R.reset_mat(),Rx.reset_mat(),Ry.reset_mat(),Rz.reset_mat(),
324     Sh.reset_mat(),TM.reset_mat(), M.reset_mat(),GRM.reset_mat(),EM.reset_mat(),Mirrorx.reset_mat(), 
325     PM.reset_mat(), WTVM.reset_mat();*/
326     for(int j=0; j<num_tm; j++)
327     {
328         for(int i=1; i<=num_vertex; i++) 
329         {
330             observe[j][i].x = poly_vertex[j][i].x; 
331             observe[j][i].y = poly_vertex[j][i].y;
332             observe[j][i].z = poly_vertex[j][i].z;
333         }
334     }
335     
336 }
337 void observer(float PX, float PY, float PZ, float CX, float CY, float CZ, float Tilt, float Near, float Far, float FOV)
338 {
339     //GRM
340     translate(-PX,-PY,-PZ);
341     //print_mat(T);
342     float x = CX-PX;
343     float y = CY-PY;
344     float z = CZ-PZ;
345     //Tilt=Tilt*PI/180.0;
346     float l=sqrt(x*x+y*y+z*z);
347     vec v(x,y,z);
348     vec t(0,1,sin(Tilt*PI/180.0));
349     vec v3;
350     v3.x = v.x/l; v3.y = v.y/l; v3.z = v.z/l;
351     vec v1=cross(v,t);
352     vec v2=cross(v1,v3);
353     GRM.m[0][0]=v1.x;    GRM.m[0][1]=v1.y;    GRM.m[0][2]=v1.z;
354     GRM.m[1][0]=v2.x;    GRM.m[1][1]=v2.y;    GRM.m[1][2]=v2.z;
355     GRM.m[2][0]=v3.x;    GRM.m[2][1]=v3.y;    GRM.m[2][2]=v3.z;
356     //GRM.m[1][2]=-0.71;
357     //float ry = abs(asin(x/sqrt(x*x+y*y+z*z)));
358     /*float ry = abs(asin(x/sqrt(x*x+y*y+z*z)));
359     float rx = atan(y/sqrt(pow(x,2.0)+pow(z,2.0)));
360     float rz = Tilt*PI/180.0;
361 
362     rotate(rx,ry,rz,1);
363     print_mat(Ry);
364     print_mat(Rx);
365     print_mat(Rz);
366     Mirrorx.m[0][0]=-1;
367     GRM = Mirrorx*Rz*Rx*Ry;*/
368     //GRM.m[1][1]=0.71;
369     //GRM.m[1][2]=-0.71;
370     //GRM.m[2][1]=-0.71;
371     //GRM.m[2][2]=-0.71;
372     //Mirrorx.m[0][0]=-1;
373     printf("GRM\n");
374     print_mat(GRM);
375     EM = Mirrorx*GRM*T;
376     //print_mat(EM);
377     transform_observe(EM);
378     //print();
379 
380     //projection(1.33,Near,Far,FOV);
381 }
382 void view(float VL, float VR, float VB, float VT)
383 {
384     DrawWindow();
385     float WL=-1, WR=1, WB=-1, WT=1;
386     translate(-WL, -WB, 0);    
387     WTVM = T * WTVM;    
388     scale((VR-VL)/(WR-WL), (VT-VB)/(WT-WB), 1);
389     WTVM = S * WTVM;    
390     translate(VL, VB, 0);    
391     WTVM = T * WTVM;
392     printf("WTVM\n");
393     print_mat(WTVM);
394     //transform_observe(WTVM);
395     
396 }
397 void display()
398 {
399     projection((VR-VL)/(VT-VB),Near,Far,FOV);
400     transform_observe(WTVM);
401     cout << "num_tm: " << num_tm << endl;
402     //cout << num_vertex << " " << num_face << endl;
403     //print();
404     for(int k=0; k<num_tm; k++)
405     {
406         for(int i=0; i<num_face; i++) 
407         {
408             for(int j=0; j<n-1; j++)
409                 DrawLines_4(observe[k][poly_face[i][j]].x, observe[k][poly_face[i][j]].y, observe[k][poly_face[i][j+1]].x, observe[k][poly_face[i][j+1]].y);
410             DrawLines_4(observe[k][poly_face[i][n-1]].x, observe[k][poly_face[i][n-1]].y, observe[k][poly_face[i][0]].x, observe[k][poly_face[i][0]].y);
411         }
412     }
413     reset();
414     EM.reset_mat();
415     PM.reset_mat();
416     WTVM.reset_mat();
417 }
418 void read_asc_file()
419 {
420     num_tm++;
421     cout << file_name << endl;
422     ifstream fin(file_name);
423     fin >> num_vertex >> num_face;
424     cout << num_vertex << " " << num_face << endl;
425     // read vertex one by one
426     for(int i=1; i<=num_vertex; i++) 
427     {
428         fin >> poly_vertex[num_tm-1][i].x >> poly_vertex[num_tm-1][i].y >> poly_vertex[num_tm-1][i].z;
429     }
430     // read face one by one
431     for(int i=0; i<num_face; i++) 
432     {
433         fin >> n;
434         for(int j=0; j<n; j++)
435             fin >> poly_face[i][j];
436     }
437     
438     transform(TM);//
439     reset();
440     TM.reset_mat();
441     
442     //print();
443 }
444 
445 void transform(mat t)
446 {
447     for(int i=1; i<=num_vertex; i++) 
448         poly_vertex[num_tm-1][i] = mat_mul_vec(t, poly_vertex[num_tm-1][i]);
449 }
450 void transform_observe(mat t)
451 {
452     for(int j=0; j<num_tm; j++)
453     {
454         for(int i=1; i<=num_vertex; i++) 
455             observe[j][i] = mat_mul_vec(t, observe[j][i]);
456     }
457 }    
458 
459 void projection(float AR, float Near, float Far, float FOV)
460 {
461     //PM
462     FOV=FOV*PI/180.0;
463     float Y=Far*tan(FOV);
464     float H=Near*tan(FOV);
465     PM.m[1][1]=AR;
466     PM.m[2][2]=Y/(Y-H)*tan(FOV);
467     PM.m[2][3]=Y*H/(H-Y)*tan(FOV);
468     PM.m[3][2]=tan(FOV);
469     PM.m[3][3]=0;
470     /*PM.m[1][1]=AR;
471     PM.m[2][2]=0.58;
472     PM.m[3][2]=0.58;
473     PM.m[3][3]=0;*
474     PM.m[2][3]=-0.58;*/
475     print_mat(PM);
476     transform_observe(PM);
477 
478     per_div();    //
479 }
480 
481 void per_div()
482 {
483     for(int j=0; j<num_tm; j++)
484     {
485         for(int i=1; i<=num_vertex; i++) 
486         {
487             observe[j][i].x /= observe[j][i].w;
488             observe[j][i].y /= observe[j][i].w;
489             observe[j][i].z /= observe[j][i].w;
490             observe[j][i].w /= observe[j][i].w;
491         }
492     }
493     
494 }
495 
496 void DrawWindow()
497 {
498     DrawLines_4(VL, VB, VR, VB);
499     DrawLines_4(VR, VB, VR, VT);
500     DrawLines_4(VR, VT, VL, VT);
501     DrawLines_4(VL, VT, VL, VB);
502 }
503 
504 void print()
505 {
506     for(int j=0; j<num_tm; j++)
507     {
508         for(int i=1; i<=num_vertex; i++)
509             cout <<  poly_vertex[j][i].x << " " << poly_vertex[j][i].y << " " << poly_vertex[j][i].z << endl;
510     }
511 }
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547 
548 //////////////////////////////////////////////////////////////////////////////////////hw1///////////////////////////////////////////////////////////
549 void DrawLines_4(int x1, int y1, int x2, int y2) //判断画哪一种线
550 {
551     if(x1 >= x2)
552     {
553         if(y1 >= y2)
554         {
555             swap(x1, x2);
556             swap(y1, y2);
557             if((y2-y1) >= (x2-x1))            
558                 drawLine2(x1, y1, x2, y2, 1);    
559             else
560                 drawLine1(x1, y1, x2, y2, 1);
561         }
562         else
563         {
564             if((y2-y1) >= (x1-x2))
565                 drawLine3(x1, y1, x2, y2, 1);
566             else
567                 drawLine4(x2, y2, x1, y1, 1);
568         }                
569     }
570     else
571     {
572         if(y2 >= y1)
573         {
574             if((y2-y1) <= (x2-x1))
575                 drawLine1(x1, y1, x2, y2, 1);
576             else
577                 drawLine2(x1, y1, x2, y2, 1);
578         }
579         else
580         {
581             if((y1-y2) <= (x2-x1))
582                 drawLine4(x1, y1, x2, y2, 1);
583             else
584                 drawLine3(x2, y2, x1, y1, 1);
585         }
586     }
587     
588     glFlush();
589 }
590 
591 // draw a dot at location with integer coordinates (x,y), and with color (r,g,b)
592 void drawDot(int x, int y, float r, float g, float b) 
593 {
594     glBegin(GL_POINTS);
595   
596     // set the color of dot
597     glColor3f(r, g, b);
598   
599     // invert height because the opengl origin is at top-left instead of bottom-left
600     glVertex2i(x ,  height-y);
601   
602     glEnd();
603 }
604 
605 // Draw line for dx>0 and dy>0
606 void drawLine1(int x1, int y1, int x2, int y2, bool xy_interchange) //0-45度
607 {
608     //cout << "Drawing Line1!" << endl;
609     int x = x1;
610     int y = y1;    
611 
612     int a = y2 - y1;
613     int b = x1 - x2;
614     int d = 2 * a + b;
615     int IncE = 2 * a;
616     int IncNE = 2 * (a + b);
617 
618     while(x <= x2)
619     {
620         if(d <= 0)
621         {
622             x++;
623             d += IncE;
624         }
625         else
626         {
627             x++;
628             y++;
629             d += IncNE;
630         }
631         drawDot(x, height-y, 0.0, 0.0, 10.0);
632         
633     }
634 }
635 
636 // Draw line for dx>0 and dy<0
637 void drawLine2(int x1, int y1, int x2, int y2, bool xy_interchange) //45-90度
638 {
639     //cout << "Drawing Line2!" << endl;
640     //转换为0-45度的情况
641     swap(x2, y2);
642     swap(x1, y1);
643 
644     int x = x1;
645     int y = y1;
646     
647     int a = y2 - y1;
648     int b = x1 - x2;
649     int d = 2 * a + b;
650     int IncE = 2 * a;
651     int IncNE = 2 * (a + b);
652 
653     while(x <= x2)
654     {
655         if(d <= 0)
656         {
657             x++;
658             d += IncE;
659         }
660         else
661         {
662             x++;
663             y++;
664             d += IncNE;
665         }
666         drawDot(y, height-x, 0.0, 0.0, 10.0);
667         
668     }    
669 }
670 
671 // Draw line for dx<0 and dy>0
672 void drawLine3(int x1, int y1, int x2, int y2, bool xy_interchange) //90-135度
673 {
674     //cout << "Drawing Line3!" << endl;
675     swap(x2, y2);
676     swap(x1, y1);
677     y1 = -y1;
678     y2 = -y2;
679     int x = x1;
680     int y = y1;
681 
682     int a = y2 - y1;
683     int b = x1 - x2;
684     int d = 2 * a + b;
685     int IncE = 2 * a;
686     int IncNE = 2 * (a + b);
687 
688     while(x <= x2)
689     {
690         if(d <= 0)
691         {
692             x++;
693             d += IncE;
694         }
695         else
696         {
697             x++;
698             y++;
699             d += IncNE;
700         }
701         drawDot(-y, height-x, 0.0, 0.0, 10.0);
702         
703     }
704 }
705 
706 // Draw line for dx<0 and dy>0
707 void drawLine4(int x1, int y1, int x2, int y2, bool xy_interchange) //135-180度
708 {
709     //cout << "Drawing Line4!" << endl;
710     y1 = -y1;
711     y2 = -y2;
712     int x = x1;
713     int y = y1;
714     
715     int a = y2 - y1;
716     int b = x1 - x2;
717     int d = 2 * a + b;
718     int IncE = 2 * a;
719     int IncNE = 2 * (a + b);
720 
721     while(x <= x2)
722     {
723         if(d <= 0)
724         {
725             x++;
726             d += IncE;
727         }
728         else
729         {
730             x++;
731             y++;
732             d += IncNE;
733         }
734         drawDot(x, height+y, 0.0, 0.0, 10.0);
735         
736     }
737 }