The problem with reflection appears to be that the CCW winding and the *transformed* normal direction are inconsistent, unlike the case of rotation. Consider, for example, a quad that is on the -ve xy plane and rotated 180 deg. about the y-axis. The result, coordinate wise, should be identical to reflection about the xz-plane, but the normals will be flipped.
There probably is an OGL way to specify the winding explicitly, but if the objective is to re-use large scenegraphs using a SharedGroup, then it becomes a wee bit difficult to treat reflection generally. Wonder, if there are any tricks to achieve this easily. >On Tue, 16 Mar 2004 01:49:14 -0700, N. Vaidya <[EMAIL PROTECTED]> wrote: >Well, I have both CULL_NONE and normalflip always set to true since I need >to see 2 lit sides always. And the problem is that setting >backFaceNormalFlip to true kills both front and back lighting on the >reflected geometry. Setting the flip flag to false, produces correct front >side lighting, but then expectedly a black back face. > >Actually, the interesting thing is that if rotation can correctly handle the >appropriate CCW winding and normal flips, what is it about reflected >geometry that causes the issue ? > >Vaidya > > > >>On Tue, 16 Mar 2004 09:41:07 +0100, Florin Herinean <[EMAIL PROTECTED]> >wrote: > >>There is a flag in the PolygonAttributes to flip the normals if the >>transform contains a reflection. However, that one works only with the >>opengl version, and not with the directx version of j3d. >> >>Cheers, >> >>Florin >> >>-----Original Message----- >>From: Discussion list for Java 3D API >>[mailto:[EMAIL PROTECTED] Behalf Of N. Vaidya >>Sent: Montag, 15. März 2004 20:55 >>To: [EMAIL PROTECTED] >>Subject: [JAVA3D] Refelction Transform & Lighting >> >> >>I'm using the following Transform3D >> >>m_00 = -1, m_11 = m_22 = m_33 = 1, and zero for all other elements, >> >>on a TransformGroup to effect a reflection of the scenegraph about >>the yz-plane. And when I do that, the geometry gets transformed correctly >>but the diffuse and specular lightings get clobbered ! >> >>Is there any issue with transforming normals with the above >>matrix structure, or am I missing something trivial ! >> >> ========================================================================== >>To unsubscribe, send email to [EMAIL PROTECTED] and include in the body >>of the message "signoff JAVA3D-INTEREST". For general help, send email to >>[EMAIL PROTECTED] and include in the body of the message "help". >> >> ========================================================================== >>To unsubscribe, send email to [EMAIL PROTECTED] and include in the body >>of the message "signoff JAVA3D-INTEREST". For general help, send email to >>[EMAIL PROTECTED] and include in the body of the message "help". > >=========================================================================== >To unsubscribe, send email to [EMAIL PROTECTED] and include in the body >of the message "signoff JAVA3D-INTEREST". For general help, send email to >[EMAIL PROTECTED] and include in the body of the message "help". =========================================================================== To unsubscribe, send email to [EMAIL PROTECTED] and include in the body of the message "signoff JAVA3D-INTEREST". For general help, send email to [EMAIL PROTECTED] and include in the body of the message "help".
