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Monday, March 22, 2010

gluUnProject source code

gluUnProject(GLdouble winx, GLdouble winy, GLdouble winz,
const GLdouble modelMatrix[16],
const GLdouble projMatrix[16],
const GLint viewport[4],
GLdouble *objx, GLdouble *objy, GLdouble *objz)
{
double finalMatrix[16];
double in[4];
double out[4];

__gluMultMatricesd(modelMatrix, projMatrix, finalMatrix);
if (!__gluInvertMatrixd(finalMatrix, finalMatrix)) return(GL_FALSE);

in[0]=winx;
in[1]=winy;
in[2]=winz;
in[3]=1.0;

/* Map x and y from window coordinates */
in[0] = (in[0] - viewport[0]) / viewport[2];
in[1] = (in[1] - viewport[1]) / viewport[3];

/* Map to range -1 to 1 */
in[0] = in[0] * 2 - 1;
in[1] = in[1] * 2 - 1;
in[2] = in[2] * 2 - 1;

__gluMultMatrixVecd(finalMatrix, in, out);
if (out[3] == 0.0) return(GL_FALSE);
out[0] /= out[3];
out[1] /= out[3];
out[2] /= out[3];
*objx = out[0];
*objy = out[1];
*objz = out[2];
return(GL_TRUE);
}

For more information: http://www.mesa3d.org/

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