// get line of sight through mouse cursor
GLint viewport[4];
GLdouble mvmatrix[16], projmatrix[16];
GLint realy; /* OpenGL y coordinate position */
GLdouble wx, wy, wz; /* returned world x, y, z coords */
GLdouble wx2, wy2, wz2; /* returned world x, y, z coords */
glGetIntegerv (GL_VIEWPORT, viewport);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glGetDoublev (GL_MODELVIEW_MATRIX, mvmatrix);
glGetDoublev (GL_PROJECTION_MATRIX, projmatrix);
/* note viewport[3] is height of window in pixels */
realy = viewport[3] - (GLint) point.y - 1;
gluUnProject ((GLdouble) point.x, (GLdouble) realy, 0.0,
mvmatrix, projmatrix, viewport, &wx, &wy, &wz);
//printf ("World coords at z=0.0 are (%f, %f, %f)\n",
// wx, wy, wz);
gluUnProject ((GLdouble) point.x, (GLdouble) realy, 1.0,
mvmatrix, projmatrix, viewport, &wx2, &wy2, &wz2);
//printf ("World coords at z=1.0 are (%f, %f, %f)\n",
// wx, wy, wz);
// line of sight intersection with y = 0 plane
double f = wy / ( wy2 - wy );
double x2d = wx - f * (wx2 - wx );
double z2d = wz - f * (wz2 - wz );
point.x、point.y 是鼠标屏幕坐标,0.0 是左上角。
该代码假设 y = 0 平面填充视口。 (您从狭窄的飞机港口俯视世界,看不到任何天空。)如果 y=0 平面没有填满视口,您必须测试 x,y 位置是否在“天空中” ' ( wy2 - wy