【循序渐进学图形学之】OpenGL绘制太阳系模型

#include <GL/glut.h>

static int year = 0,day = 0,d = 0;

void init()
{
glClearColor(0.0,0.0,0.0,0.0);
glShadeModel(GL_FLAT);//着色模型
}

void reshape(int w,int h)
{
glViewport(0,0,(GLsizei)w,(GLsizei)h);//在窗口中定义一个像素矩形，最终的图像将映射到这个矩形中
glMatrixMode(GL_PROJECTION);//设置当前矩阵模式:对投影矩阵应用随后的矩阵操作
glLoadIdentity();//重置当前指定的矩阵为单位矩阵.隔离各个模型变换的效果，防止连续变换产生的累积效果
gluPerspective(60.0,(GLfloat)w / (GLfloat)h,1.0,20.0);//创建一个表示对称透视视图平截头体的矩阵，并把它与当前矩阵相乘
glMatrixMode(GL_MODELVIEW);//对模型视景矩阵堆栈应用随后的矩阵操作
glLoadIdentity();
gluLookAt(0.0,5.0,5.0,0.0,0.0,0.0,0.0,1.0,0.0);//定义一条视线
}

void display()
{
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1.0,0.0,0.0);

glPushMatrix();//pushes the current matrix stack down by one, duplicating the current matrix
//绘制太阳
glutWireSphere(1.0,20,16);//render a wireframe sphere
//绘制行星
glRotatef((GLfloat)year,0.0,1.0,0.0);//绕向量(0.0,1.0,0.0)旋转角度(第一个参数)
glTranslatef(2.0,0.0,0.0);//平移
glRotatef((GLfloat)day,0.0,1.0,0.0);
glutWireSphere(0.2,10,8);
//增加一颗卫星
glTranslatef(1.0,0.0,0.0);//平移
glRotatef((GLfloat)d,0.0,1.0,0.0);
glutWireSphere(0.5,10,8);
glPopMatrix();
glutSwapBuffers();//互换缓存（双缓存时候）
}

void keyboard(unsigned char key,int x,int y)
{
switch(key){
case 'd':
day = (day + 10) % 360;
glutPostRedisplay();//标记当前窗口需要重新绘制。通过glutMainLoop下一次循环时，
//窗口显示将被回调以重新显示窗口的正常面板
break;
case 'D':
day = (day - 10) % 360;
glutPostRedisplay();
break;
case 'y':
year = (year + 5) % 360;
glutPostRedisplay();
break;
case 'Y':
year = (year - 5) % 360;
glutPostRedisplay();
break;
case 'p':
d = (d + 5) % 360;
glutPostRedisplay();
break;
case 'P':
d = (d - 5) % 360;
glutPostRedisplay();
break;
default:
break;
}
}

int main(int argc,char** argv)
{
glutInit(&argc,argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
glutInitWindowSize(500,500);
glutInitWindowPosition(100,100);
glutCreateWindow(argv[0]);
init();
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutKeyboardFunc(keyboard);
glutMainLoop();
return 0;
}