I have a problem with GLU.gluUnProject() function. I am traying to unproject mouse coordinates in the viewport to the ZX plane in my 3D scene. I wrote the following code:
public Point3D.Double DPtoLP(int x, int y) {
GLContext context = this.getContext();
context.makeCurrent();
final GL OpenGL = context.getGL();
float winX = (float)x;
float winY = (float)y;
int[] viewport = new int[4];
double[] modelview = new double[16];
double[] projection = new double[16];
OpenGL.glGetIntegerv(GL.GL_VIEWPORT, viewport, 0);
OpenGL.glGetDoublev(GL.GL_MODELVIEW_MATRIX, modelview, 0);
OpenGL.glGetDoublev(GL.GL_PROJECTION_MATRIX, projection, 0);
winY = (float)viewport[3] - winY;
double[] nearPos = new double[3];
double[] farPos = new double[3];
glu.gluUnProject(winX, winY, 0.0, modelview, 0, projection, 0, viewport, 0,
nearPos, 0);
glu.gluUnProject(winX, winY, 1.0, modelview, 0, projection, 0, viewport, 0,
farPos, 0);
double sx = farPos[0] - nearPos[0];
double sy = farPos[1] - nearPos[1];
double sz = farPos[2] - nearPos[2];
double a = nearPos[0] - (nearPos[1]/sy)*sx;
double b = nearPos[2] - (nearPos[1]/sy)*sz;
context.release();
return new Point3D.Double(a, 0.0, b);
}
Variables a, b should be x, z coordinates on the XZ plane. But when I execute this code there is complete rubbish in a,b variables. Has anyone any idea why this code does not work? Maybe am making some very silly mistake…