在xy平面上绕z轴连续旋转一个正六边形。
#include#include#include
const double TWO_PI = 6.2831853;
GLsizei winWidth = 500, winHeight = 500;
GLuint regHex; //Define name for display list
static GLfloat rotTheta = 0.0;
class scrPt
{
public:
GLint
x, y;
};
static void init(void){
scrPt hexVertex;
GLdouble hexTheta;
GLint k;
glClearColor(1.0, 1.0, 1.0, 0.0);
/* set up a display list for a red regular hexagon */
/* Vertices for the hexagon are six equally spaced points around the circumference of a circle */ //六边形的顶点在圆周上是6个等距点
//glGenLists(GLuint range)是更安全的创建列表的函数 由于创建的显示列表组是连续的，glGenLists()首先检查有哪些值已经被占用，然后从最小的值开始建立连续的显示列表
regHex = glGenLists(1);
glNewList(regHex, GL_COMPILE); //类似glBegin
glColor3f(1.0, 0.0, 0.0);
glBegin(GL_POLYGON);
for (k = 0; k < 6; k++){
hexTheta = TWO_PI*k / 6;
hexVertex.x = 150 + 100 * cos(hexTheta);
hexVertex.y = 150 + 100 * sin(hexTheta);
glVertex2i(hexVertex.x, hexVertex.y);
}
glEnd();
glEndList();
}
void displayHex(void){
glClear(GL_COLOR_BUFFER_BIT);
glPushMatrix();
glRotatef(rotTheta, 0.0, 0.0, 1.0);
glCallList(regHex);
glPopMatrix();
glutSwapBuffers();
glFlush();
}
/*用于激活旋转，在每次按下鼠标中键时将旋转角度增加3°*/
void rotateHex(void) {
rotTheta += 3.0;
if (rotTheta > 360.0){
rotTheta -= 360.0;
glutPostRedisplay();
}
}
void winReshapeFcn(GLint newWidth, GLint newHeight){
glViewport(0, 0, (GLsizei)newWidth, (GLsizei)newHeight);
glMatrixMode(GL_PROJECTION);
//glLoadIdentity()的作用就是把矩阵堆栈中的在栈顶的那个矩阵置为单位矩阵，好让之前的任何变换都不影响后面的变化。
glLoadIdentity();
gluOrtho2D(-320.0, 320.0, -320.0, 320.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glClear(GL_COLOR_BUFFER_BIT);
}
void mouseFcn(GLint button, GLint action, GLint x, GLint y){
switch (button)
{
case GLUT_MIDDLE_BUTTON: //start the rotation
if (action == GLUT_DOWN)
glutIdleFunc(rotateHex);
break;
case GLUT_RIGHT_BUTTON:
if (action==GLUT_DOWN)
glutIdleFunc(NULL);
break;
default:
break;
}
}
int main(int argc, char**argv){
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
glutInitWindowPosition(150, 150);
glutInitWindowSize(winWidth, winHeight);
glutCreateWindow("Aniomation Example");
init();
glutDisplayFunc(displayHex);
glutReshapeFunc(winReshapeFcn);
glutMouseFunc(mouseFcn);
glutMainLoop();
return 0;
}