OpenGL——旋轉的六邊形（動畫）

代碼：

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

using namespace std;

const double TWO_PI = 6.2831853;

GLsizei winWidth = 500, winHeight = 500;
GLuint regHex;
static GLfloat rotTheta;

class scrPt {
public:
    GLint x, y;
};


void init()
{
    scrPt hexVertex;
    GLdouble hexTheta;

    glClearColor(1.0, 1.0, 1.0, 0.0);
    //創建1個顯示列表
    regHex = glGenLists(1);
    //編譯顯示列表
    glNewList(regHex, GL_COMPILE);
        glColor3f(209.0 / 255.0, 73.0 / 255.0, 78.0 / 255.0);
        glBegin(GL_POLYGON);
            for (GLint 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()
{
    glClear(GL_COLOR_BUFFER_BIT);
    glPushMatrix();
    //旋轉操作
    glRotatef(rotTheta, 0.0, 0.0, 1.0);
    //執行顯示列表
    glCallList(regHex);    
    glPopMatrix();
    //互換緩存
    glutSwapBuffers();                
    glFlush();
}

//計算增加的旋轉角度
void rotateHex()
{
    rotTheta += 3.0;
    if (rotTheta > 360.0) {
        rotTheta -= 360.0;
    }
    //標記當前窗口需要重新繪制
    //通過glutMainLoop下一次循環時，窗口顯示將被回調以重新顯示窗口的正常面板
    glutPostRedisplay();
}


void winReshapeFcn(GLint newWidth, GLint newHeight)
{
    glViewport(0, 0, (GLsizei)newWidth, (GLsizei)newHeight);

    glMatrixMode(GL_PROJECTION);
    //重置當前指定的矩陣為單位矩陣，相當於復位操作
    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_LEFT_BUTTON:                //鼠標左鍵，開始旋轉
        if (action == GLUT_DOWN) {
            //全局的回調函數，如果啟用則rotateHex會被不斷調用，直到有窗口事件發生
            glutIdleFunc(rotateHex);
        }
        break;
    case GLUT_RIGHT_BUTTON:                    //鼠標右鍵，停止旋轉
        if (action == GLUT_DOWN) {
            //參數為NULL說明不改變
            glutIdleFunc(NULL);
        }
        break;
    defalut:
        break;
    }
}

int main(int argc, char* argv[])
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
    glutInitWindowPosition(100, 100);

    glutInitWindowSize(winWidth, winHeight);
    glutCreateWindow("第一個動畫程序");
    init();
    glutDisplayFunc(displayHex);
    glutReshapeFunc(winReshapeFcn);
    glutMouseFunc(mouseFcn);
    glutMainLoop();

    system("pause");
    return 0;
}

運行結果：