OpenGL显示窗口重定形函数
我们在建立初始显示窗口后，需要在其后改变位置与形状。窗口尺寸的改变可能改变其纵横比并引起对象形状的改变。所以GLUT库提供glutReshapeFunc(winReshapeFcn)函数。和其他GLUT函数一起放在程序的主过程中，不过该函数是在窗口尺寸输入后激活。其参数是接受新窗口高度的过程名。还可以接着使用新尺寸去重新设置投影参数并完成任何其他操作，包括改变显示窗口颜色。另外，可以保存宽度和高度供其它子程序使用。
void glutReshapeFunc(void (*func)(int width, int height));
官方文档在这里。
1 #include <GL/glut.h> 2 #include <cmath> 3 #include <cstdlib> 4 5 const double TWO_PI = 6.2831853; 6 7 GLsizei winWidth = 400, winHeight = 400; 8 GLuint regHex; 9 10 class screenPt { 11 private: 12 GLint x, y; 13 14 public: 15 screenPt() { 16 x = y = 0; 17 } 18 void setCoords(GLint xCoord, GLint yCoord) { 19 x = xCoord; 20 y = yCoord; 21 } 22 GLint getx() const { 23 return x; 24 } 25 GLint gety() const { 26 return y; 27 } 28 }; 29 30 static void init(void) 31 { 32 screenPt hexVertex, circCtr; 33 GLdouble theta; 34 GLint k; 35 36 circCtr.setCoords(winWidth/2, winHeight/2); 37 38 glClearColor(1.0, 1.0, 1.0, 0.0); 39 40 regHex = glGenLists(1); 41 glNewList(regHex, GL_COMPILE); 42 glColor3f(1.0, 0.0, 0.0); 43 glBegin(GL_POLYGON); 44 for (k = 0; k < 6; ++k) { 45 theta = TWO_PI * k / 6.0; 46 hexVertex.setCoords(circCtr.getx() + 150 * cos(theta), 47 circCtr.gety() + 150 * sin(theta)); 48 glVertex2i(hexVertex.getx(), hexVertex.gety()); 49 } 50 glEnd(); 51 glEndList(); 52 } 53 54 void regHexagon() 55 { 56 glClear(GL_COLOR_BUFFER_BIT); 57 58 glCallList(regHex); 59 60 glFlush(); 61 } 62 63 void winReshapeFcn(int newWidth, int newHeight) 64 { 65 glMatrixMode(GL_PROJECTION); 66 glLoadIdentity(); 67 gluOrtho2D(0.0, (GLdouble)newWidth, 0.0, (GLdouble)newHeight); 68 69 glClear(GL_COLOR_BUFFER_BIT); 70 } 71 72 int main(int argc, char* argv[]) 73 { 74 glutInit(&argc, argv); 75 glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); 76 glutInitWindowPosition(100, 100); 77 78 glutInitWindowSize(winWidth, winHeight); 79 glutCreateWindow("Reshape-Function & Display-List Example"); 80 81 init(); 82 glutDisplayFunc(regHexagon); 83 glutReshapeFunc(winReshapeFcn); 84 85 glutMainLoop(); 86 return 0; 87 }
