讓物體自己轉動

(3)讓物體自己轉動，不用一直按按鍵了!

#include <GL/glut.h>

float a = 0; //內插法比重 

// 利用陣列, 存許多角度

float angle[20] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};  

float angleOld[20] = {0,90,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}; 

float angleNew[20] = {90,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}; 

void display()

{

     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

     glPushMatrix();

      glRotatef(angle[0], 0,0,1);

      glutSolidTeapot(0.3);

     glPopMatrix();

     glPushMatrix();

      glTranslatef(0.5, 0,0);

glRotatef(angle[1], 0,0,1);

glutSolidTeapot(0.3);

     glPopMatrix();

     glutSwapBuffers();

}

void readNext()

{

a += 0.1; //比重一直增加，角度才會變化 

for( int i=0; i<=20; i++){ //用for可以一次打20個

angle[i] = angleOld[i] * (1-a) + angleNew[i] * a;

}

}

void timer(int t)

{

glutTimerFunc(100, timer, 0);

readNext();

glutPostRedisplay();

} 

void keyboard(unsigned char key, int x, int y)

{

if (key == 'r'){

readNext();

}

else if (key== 'p'){

glutTimerFunc(0, timer, 0);

}

glutPostRedisplay();

}

int main()

{

glutInitDisplayMode(GLUT_DOUBLE | GLUT_DEPTH);

glutCreateWindow("week15");

glutKeyboardFunc(keyboard);

glutDisplayFunc(display);

glutMainLoop();

}