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问题描述
我有这个视图集：
glMatrixMode（GL_MODELVIEW）; //切换到图形透视图 glLoadIdentity（）; //重新绘制透视图我从鼠标单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x和y的三维空间？
解决方案您应该使用 gluUnProject ： 首先，计算对近平面unprojection：
GLdouble modelMatrix [16]; GLdouble projMatrix [16]; GLint视口[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）;然后到达远处：
//将上面的gluUnProject调用替换为 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有一条线，可以找出所有可能的点已被点击。所以现在你只需要插入：假设你得到了z坐标：
GLfloat nearv [3]，farv [ 3]; //已经如上计算 if（nearv [2] == farv [2]）//这意味着我们没有解决方案 return; GLfloat t =（nearv [2] - z）/（nearv [2] - farv [2]）; //所以这里是所需的（x，y）坐标 GLfloat x = nearv [0] +（farv [0] - nearv [0]）* t，y = nearv [1] +（farv [1] - nearv [1]）* t;
I have this view set:
glMatrixMode(GL_MODELVIEW); //Switch to the drawing perspective glLoadIdentity(); //Reset the drawing perspectiveand I get a screen position (sx, sy) from a mouse click.
Given a value of z, how can I calculate x and y in 3d-space from sx and sy?
解决方案You should use gluUnProject:
First, compute the "unprojection" to the near plane:
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);and then to the far plane:
// replace the above gluUnProject call with gluUnProject(sx, viewport[1] + viewport[3] - sy, 1, modelMatrix, projMatrix, viewport, &x, &y, &z);Now you've got a line in world coordinates that traces out all possible points you could have been clicking on. So now you just need to interpolate: suppose you're given the z-coordinate:
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;
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