OpenGL:将鼠标点击到几何体上

我有这个视图集:

glMatrixMode(GL_MODELVIEW); //Switch to the drawing perspective
glLoadIdentity(); //Reset the drawing perspective

然后我从鼠标点击中获得一个屏幕位置(sx,sy).

给定z的值,如何从sx和sy计算3d空间中的x和y？

你应该用 gluUnProject:

首先,计算近平面的"不投影":

GLdouble modelMatrix[16];
GLdouble projMatrix[16];
GLint viewport[4];

glGetIntegerv(GL_VIEWPORT, viewport);
glGetDoublev(GL_MODELVIEW_MATRIX, modelMatrix);
glGetDoublev(GL_PROJECTION_MATRIX, projMatrix);

GLdouble x, y, z;
gluUnProject(sx, viewport[1] + viewport[3] - sy, 0, modelMatrix, projMatrix, viewport, &x, &y, &z);

然后到远处飞机:

// replace the above gluUnProject call with
gluUnProject(sx, viewport[1] + viewport[3] - sy, 1, modelMatrix, projMatrix, viewport, &x, &y, &z);

现在,您已经在世界坐标中找到了一条线,可以找出您可能点击的所有可能点.所以现在你只需要插值:假设你给了z坐标:

GLfloat nearv[3], farv[3];  // already computed as above

if(nearv[2] == farv[2])     // this means we have no solutions
   return;

GLfloat t = (nearv[2] - z) / (nearv[2] - farv[2]);

// so here are the desired (x, y) coordinates
GLfloat x = nearv[0] + (farv[0] - nearv[0]) * t,
        y = nearv[1] + (farv[1] - nearv[1]) * t;