旋转5圈问题 [英] rotate 5 circle problem

问题描述

可能的重复:
如何旋转这个openGl代码…

下面是我的代码，它工作正常..我画了 5 个戒指.

below is my code and it work fine.. i draw 5 ring in this.

#include <GL/glut.h>
#include <math.h>

static void redraw(void);
#define PI 3.14159265 
#define EDGES 90
#define factor 10


void display (void) 
{
    glClearColor(1.0,1.0,1.0,0.0);
     glMatrixMode (GL_MODELVIEW);
    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
    glLoadIdentity();   


//ring1 
glPushMatrix();
glColor3f (0.0, 0.0 ,1.0);
glTranslatef(-30.0,10.0,-100.0);
redraw();
glutSwapBuffers();
glPopMatrix();

//ring2
glPushMatrix();
glColor3f (0.0, 0.0, 0.0);
glTranslatef(-8.0,10.0,-100.0);
redraw();
glutSwapBuffers();
glPopMatrix();

//ring3
glPushMatrix();
glColor3f (1.0, 0.0 ,0.0);
glTranslatef(14.0,10.0,-100.0);
redraw();
glutSwapBuffers();
glPopMatrix();

//ring4
glPushMatrix();
glColor3f (1.0, 1.0, 0.0);
glTranslatef(-19.0,-2.0,-100.0);
redraw();
glutSwapBuffers();
glPopMatrix();

//ring5
glPushMatrix();
glColor3f (0.0, 1.0, 0.0);
glTranslatef(4.0,-2.0,-100.0);
redraw();
glutSwapBuffers();
glPopMatrix();

}

static void redraw(void)
{
for (int i = 0; i < EDGES; i++)
    { 
      glBegin(GL_LINE_LOOP); 
      glVertex2f(factor*cos((2*PI*i)/EDGES),factor*sin((2*PI*i)/EDGES)); 
      glVertex2f(factor*cos((2*PI*(i+1))/EDGES),factor*sin((2*PI*(i+1))/EDGES)); 
      glEnd();
     } 
}

int main(int argc, char **argv)
{
glutInit(&argc,argv);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
glutInitWindowPosition(100,100);
glutInitWindowSize(110*3, 110*3);
glutCreateWindow("draw circle");
glPointSize(3); 
glShadeModel (GL_FLAT); 
glutDisplayFunc(display);
glMatrixMode(GL_PROJECTION);    
gluPerspective(45,1.0,10.0,200.0);
glMatrixMode(GL_MODELVIEW);
glutMainLoop();
return 0; 
}

所以我想旋转所有这个圆圈..我该怎么做??

so i want to rotate all of this circle.. how can i do??

推荐答案

你应该在绘图函数中只调用一次 glutSwapBuffers.

You should call glutSwapBuffers only once in the drawing function.

对于一个动画，你必须调用glutPostRedisplay，以确保再次调用显示函数.

For an animation you have to call glutPostRedisplay, to ensure that the display function will be called again.

glBegin 和 glEnd 调用只需在每个圆圈中调用一次.在 for 循环中，您只需提供调用 glVertex 的顶点.

The glBegin and glEnd calls only have to be called once per circle. In the for loop you just supply vertices with calls to glVertex.

为了简化调试，我安装了一个键盘处理程序，当按下转义键时关闭窗口.

To simplify debugging I installed a keyboard handler that closes the window when the escape key is pressed.

 // compile in linux: gcc ogl.c -lglut -lGLU

#include <GL/glut.h>
#include <math.h>
#include <stdlib.h>

static void redraw(void);
#define PI 3.14159265 

enum{
  EDGES=90,
};

static void 
circle(float radius)
{
  int i;
  glBegin(GL_LINE_LOOP); 
  for (i = 0; i < EDGES; i++){ 
    glVertex2f(radius*cos((2*PI*i)/EDGES),
           radius*sin((2*PI*i)/EDGES)); 
    glVertex2f(radius*cos((2*PI*(i+1))/EDGES),
           radius*sin((2*PI*(i+1))/EDGES)); 
  } 
  glEnd();
}


int count=0;
void display (void) 
{
  float r=10;
  glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
  glLoadIdentity();   

  glRotated(count,0,0,1);
  count++;
  if(count>360)
    count=0;

  glPushMatrix();
  // ring1
  glColor3f (0.0, 0.0 ,1.0);
  glTranslatef(-30.0,10.0,-100.0);
  circle(r);
  glPopMatrix();

  glPushMatrix();
  // ring2
  glColor3f (0.0, 0.0, 0.0);
  glTranslatef(-8.0,10.0,-100.0);
  circle(r);
  glPopMatrix();

  glPushMatrix();
  //ring3
  glColor3f (1.0, 0.0 ,0.0);
  glTranslatef(14.0,10.0,-100.0);
  circle(r);
  glPopMatrix();

  glPushMatrix();
  //ring4
  glColor3f (1.0, 1.0, 0.0);
  glTranslatef(-19.0,-2.0,-100.0);
  circle(r);
  glPopMatrix();

  glPushMatrix();
  //ring5
  glColor3f (0.0, 1.0, 0.0);
  glTranslatef(4.0,-2.0,-100.0);
  circle(r);
  glPopMatrix();

  glutSwapBuffers();
  glutPostRedisplay();
}

static void 
keyb(unsigned char key, int x, int y)
{
  switch (key) {
  case 27:  /* Escape key */
    exit(0);
  }
}


void
init()
{
  glPointSize(3); 
  glShadeModel (GL_FLAT); 
  glMatrixMode(GL_PROJECTION);    
  gluPerspective(45,1.0,10.0,200.0);
  glMatrixMode(GL_MODELVIEW);
  glClearColor(1.0,1.0,1.0,0.0);
  glLineWidth(2);
}

int
main(int argc, char **argv)
{
  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
  glutInitWindowPosition(100,100);
  glutInitWindowSize(110*3, 110*3);
  glutCreateWindow("draw circle");
  glutDisplayFunc(display);
  glutKeyboardFunc(keyb);
  init();
  glutMainLoop();
  return 0; 
}

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