OpenGL draws a simple clock (first test) and opengl draws

OpenGL draws a simple clock (first test) and opengl draws

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1 # include <windows. h> 2 # include <GL/glut. h> // originally, OpenGL programs generally need to include <GL/gl. h> and <GL/glu. h>, 3 // but the GLUT header file automatically contains the two files and does not need to be included again. 4 # include <math. h> 5 # include <time. h> 6 7 const GLfloat Pi = 3.1415926536; 8 const GLfloat R = 0.8f; 9 const int n = 200; 10 static GLfloat angle = 2 * Pi; 11 12 float Mysecond (struct tm * ptr) 13 {14 return (Pi/2)-(float) ptr-> tm_sec)/60) * 2 * Pi ); 15 16} 17 18 float Mymin (struct tm * ptr) 19 {20 // return (Pi/2)-(ptr-> tm_min + (float) ptr-> tm_sec)/60)/60) * 2 * Pi); 21 return (Pi/2)-(ptr-> tm_min + (Myseco Nd (ptr)/60)/60) * 2 * Pi); 22}; 23 24 float Myhour (struct tm * ptr) 25 {26 if (0 <ptr-> tm_hour & ptr-> tm_hour <12) 27 {28 return (Pi/2)-(float) ptr-> tm_hour + Mymin (ptr)/60.0)/12.0*2 * Pi); 29} else {30 return (Pi/2) -(ptr-> tm_hour-12.0 + Mymin (ptr)/60.0)/12) * 2 * Pi); 31} 32}; 33 void myDisplay (void) 34 35 {36 // glShadeModel (GL_SMOOTH); 37 // obtain the system time 38 struct tm * ptr; 39 time_t it; 40 it = time (NULL); 41 ptr = Localtime (& it); 42 43 glClear (GL_COLOR_BUFFER_BIT); // clear, period indicates that the color is 44 glEnable (GL_POINT_SMOOTH); 45 glable (GL_LINE_SMOOTH); 46 glHint (limit, GL_NICEST); // Make round points, not square points 47 glHint (random, GL_NICEST); // Antialias the lines 48 glable (GL_BLEND); 49 glBlendFunc (GL_SRC_ALPHA, random ); 50 // 51 glColor3f (0.5, 0.5, 0. 5); 52 glBegin (GL_POLYGON); 53 for (int I = 0; I <n; I ++) {54 glVertex2f (R * cos (2 * Pi/n * I), R * sin (2 * Pi/n * I); 55} 56 glEnd (); 57 58 // scale 59 glColor3f (1.0, 1.0, 1.0); 60 glBegin (GL_POINTS); 61 glPointSize (5.0f); 62 for (int j = 0; j <12; j ++) 63 {64 glVertex2f (0.75 * cos (2 * Pi/12 * j), 0.75 * sin (2 * Pi/12 * j )); 65 // for (int k = 66} 67 68 glEnd (); 69 // center 70 glPointSize (5.0f); 71 glColor3f (0.0, 0.0, 0.0); 72 glBegin (GL_POIN TS); 73 glVertex2f (0.0, 0.0); 74 glEnd (); 75 76 // 77 glLineWidth (5.0f); 78 glColor3f (0.0, 0.0, 0.0 ); // red 79 // glRotatef (angle/3600.0), 0.0, 0.0, 1.0); 80 81 glBegin (GL_LINES); 82 glRotatef (angle/3600.0), 0.0, 0.0, 1.0); 83 glVertex2f (0.0, 0.0); 84 glVertex2f (cos (Myhour (ptr) * R * 0.55, sin (Myhour (ptr )) * R * 0.55); 85 glEnd (); 86 87 // split needle 88 glLineWidth (5.0f); 89 glColor3f (0.0, 0.0, 0.0 ); // Green 90 // glRotatef (angl E/60.0), 0.0, 0.0, 1.0); 91 92 glBegin (GL_LINES); 93 glRotatef (angle/60.0), 0.0, 0.0, 1.0); 94 glVertex2f (0.0, 0.0); 95 glVertex2f (cos (Mymin (ptr) * R * 0.65, sin (Mymin (ptr) * R * 0.65); 96 glEnd (); 97 98 // seconds 99 glLineWidth (3.0f); 100 glColor3f (0.0, 0.0, 0.0); // blue 101 // glRotatef (angle, 0.0, 0.0, 1.0 ); 102 103 glBegin (GL_LINES); 104 glRotatef (angle, 0.0, 0.0, 1.0); 105 glVertex2f (0.0, 0.0); 106 glVertex2f (cos (Mysecond (ptr ))* R * 0.85, sin (Mysecond (ptr) * R * 0.85); 107 glEnd (); 108 glFlush (); // glFlush, ensure that the previous OpenGL commands are executed immediately (instead of waiting them in the buffer ). 109 110} 111 112 void myIdle (void) 113 {114 angle-= (2 * Pi)/60); 115 Sleep (1000); 116 if (angle <0.0f) {117 angle = 2 * Pi; 118} 119 myDisplay (); 120} 121 122 int main (int argc, char * argv []) 123 124 {125 126 gluinit (& argc, argv); // gluinit, which is called once before other gluts are used. The format is relatively rigid. You can copy this keyword according to the format of gluinit (& argc, argv. 127 128 gluinitdisplaymode (glu_rgb | glu_single); // you can specify the display mode. In this case, glu_rgb indicates that the RGB color is used, and the corresponding glu_index indicates that the index color is used. Glu_single indicates that a single buffer is used, and the corresponding value is glu_double (dual buffer) 129 130 gluinitwindowposition (300,100); // you can specify the position of the window on the screen. 131 132 glutInitWindowSize (400,400); // you can specify the window size as 133. 134. The parameter is used as the title of the window. Note: The window is not displayed on the screen immediately after it is created. You need to call the glumainloop function to view the window. 135 136 gludisplayfunc (& myDisplay); // call the plotting function 137 glutIdleFunc (& myIdle); 138 139 glumainloop (); // perform a message loop. This function can display the window, and will return 140 141 return 0; 142 143} only after the window is closed}

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