private void modifyProjectionMatrix(final Vector4 clipPlane) {
// Get the current projection matrix
projectionMatrix = cam.getProjectionMatrix().toArray(projectionMatrix);
// Get the inverse transpose of the current modelview matrix
final ReadOnlyMatrix4 modelViewMatrixInvTrans =
tRenderer.getCamera().getModelViewMatrix().invert(tmpMatrix).transposeLocal();
modelViewMatrixInvTrans.applyPre(clipPlane, clipPlane);
// Calculate the clip-space corner point opposite the clipping plane
// as (sgn(clipPlane.x), sgn(clipPlane.y), 1, 1) and
// transform it into camera space by multiplying it
// by the inverse of the projection matrix
cornerPoint.setX((sign(clipPlane.getX()) + projectionMatrix[8]) / projectionMatrix[0]);
cornerPoint.setY((sign(clipPlane.getY()) + projectionMatrix[9]) / projectionMatrix[5]);
cornerPoint.setZ(-1.0);
cornerPoint.setW((1.0 + projectionMatrix[10]) / projectionMatrix[14]);
// Calculate the scaled plane vector
final Vector4 scaledPlaneVector =
clipPlane.multiply((2.0 / clipPlane.dot(cornerPoint)), cornerPoint);
// Replace the third row of the projection matrix
projectionMatrix[2] = scaledPlaneVector.getX();
projectionMatrix[6] = scaledPlaneVector.getY();
projectionMatrix[10] = scaledPlaneVector.getZ() + 1.0;
projectionMatrix[14] = scaledPlaneVector.getW();
// Load it back into OpenGL
final Matrix4 newProjectionMatrix = tmpMatrix.fromArray(projectionMatrix);
tRenderer.getCamera().setProjectionMatrix(newProjectionMatrix);
}
/**
* Internally modifies this vector by multiplying its values with a given scale value, then adding
* a given "add" value.
*
* @param scale the value to multiply this vector by.
* @param add the value to add to the result
* @return this vector for chaining
*/
public Vector4 scaleAddLocal(final double scale, final Vector4 add) {
_x = _x * scale + add.getX();
_y = _y * scale + add.getY();
_z = _z * scale + add.getZ();
_w = _w * scale + add.getW();
return this;
}