Posted by andys on Dec 09, 2010; 2:03pm
URL: https://forum.jogamp.org/Viewing-transformations-cleared-after-glLoadMatrix-tp2056651p2057815.html

puuhhh,

another 2 hours hard thinking and endless try and error code testing i found this fix for my glLoadMatrix() thing:

I shouldn't load the matrix via glLoadMatrix!

    gl.glLoadMatrixf(glMat, 0);   ---> draws objects o.k., but wipes out my view transformation even if i Push/Pop Modelview Matrix


Instead:
i should multiply current ModelView Matrix via glMultMatrix with it!

   gl.glMultMatrixf(glMat, 0);   ---> draws objects o.k. AND keeps my view transformation

Honestly: i have no idea why i need to multiply instead of just replacing the current ModelView matrix. I just tried all possible commands which manipulate the matrix - and this one did exactly what i need to keep my view transformation. The main thing what REALLY puzzles me is:  why the glLoadMatrix change cannot be undone via a Push/Pop?????

Still i do absolutely not understand why  my view transformation is gone if i
-) Push Matrix - i even pushed all Attributes via glPushAttrib(GL2.GL_ALL_ATTRIB_BITS)
-) replace the current modelview matrix via glLoadMatrix
-) draw the object
-) Pop Matrix (and all Attributes)

Maybe somebody has a basic explanation for me - could it be something inside JBullet  code which neutralizes any previous,post transformations? .

I have to admit that my level of Matrix understanding is still pretty basic. Getting normals via cross product is o.k. , but beyond that ... very feeble knowledge, but improving .

Cheers
   Andy