I'm trying to convert the following code so that a point SX,SY,SZ can be selected and moved around. The thing is the SZ should stay the same distance during moving around but still the point stays sync-ed with the mouse pointer. The following code will return mouse coordinates with z=0 void MouseTo3d() { glFlush(); POINT pt; GetCursorPos(&pt); 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; glGetIntegerv (GL_VIEWPORT, viewport); glGetDoublev (GL_MODELVIEW_MATRIX, mvmatrix); glGetDoublev (GL_PROJECTION_MATRIX, projmatrix); // note viewport[3] is height of window in pixels realy = viewport[3] - (GLint) mousey - 1; //float depth; //glReadPixels(pt.x,realy,1,1,GL_DEPTH_COMPONENT, GL_FLOAT, &depth); gluUnProject ((GLdouble) mousex, (GLdouble) realy, 0, mvmatrix, projmatrix, viewport, &wx, &wy, &wz); gluUnProject ((GLdouble) mousex, (GLdouble) realy, 1.0f, mvmatrix, projmatrix, viewport, &wx2, &wy2, &wz2); double x_AB = (wx2 - wx); double y_AB = (wy2 - wy); double z_AB = (wz2 - wz); double factor_t; if (y_AB!=0 && CW==3) factor_t = - (wy2 / (y_AB)); if (y_AB==0 && CW==3) factor_t=0; if (x_AB!=0 && CW==1) factor_t = - (wx2 / (x_AB)); if (x_AB==0 && CW==1) factor_t=0; if (z_AB!=0 && CW==2) factor_t = - (wz2 / (z_AB)); if (z_AB==0 && CW==2) factor_t=0; space_x = wx2 + (factor_t * x_AB); space_y = wy2 + (factor_t * y_AB); space_z = wz2 + (factor_t * z_AB); } [edited by - bgcjr on September 5, 2002 11:28:23 PM]

i figured a solution:

GLint viewport[4];
glGetIntegerv (GL_VIEWPORT, viewport);
GLint realy = viewport[3] - (GLint) mousey - 1;
glReadPixels(mousex,realy,1,1,GL_DEPTH_COMPONENT, GL_FLOAT, &depth);

As long as the scene view depth is not altered then depth of object stays the same.
so need to update it til that happens.


then:

gluUnProject ((GLdouble) mousex, (GLdouble) realy, depth,
mvmatrix, projmatrix, viewport, &wx2, &wy2, &wz2);