From: Phlip <phlip_cpp@...>
Date: 2001-11-29T15:14:00+09:00
Subject: [ruby-talk:26871] FXGLViewer - rotate a primitive?

Rubies:

I finally got back to this effort; here's a recap regarding this example 
code:

        FXRuby-0.99.174/examples/glviewer.rb

Open it up and eyeball this line:

        gp2.append(FXGLCylinder.new(-1.0, 0.5, 0.0, 1.0, 0.5))

Now suppose I feel that vertical cylinders are boring. I want to
rotate this cylinder (not the whole scene - just the cylinder) 30
degrees over.

My experiments with C OpenGL sample code reveals that to rotate one pushes 
the current transformation matrix, builds a new one with what you want in 
it, paints a gluCylinder in, and then pops the matrix. However, when I open 
up FXGLCylinder.cpp, I find this function:

// Draw
void FXGLCylinder::drawshape(FXGLViewer*){
#ifdef HAVE_OPENGL
  GLUquadricObj* quad=gluNewQuadric();
  gluQuadricDrawStyle(quad,(GLenum)GLU_FILL);
  /*
    gluQuadricNormals(quad,GLU_SMOOTH);
    gluQuadricOrientation(quad,GLU_OUTSIDE);
  */
  glPushMatrix();
  glRotatef(-90,1,0,0);
  
gluCylinder(quad,radius,radius,height,FXGLCYLINDER_SLICES_NUMBER,FXGLCYLINDER_STACKS_NUMBER);

  gluQuadricOrientation(quad,(GLenum)GLU_INSIDE);
  gluDisk(quad,0,radius,FXGLCYLINDER_SLICES_NUMBER,FXGLCYLINDER_LOOPS);

  glTranslatef(0,0,height);
  gluQuadricOrientation(quad,(GLenum)GLU_OUTSIDE);
  gluDisk(quad,0,radius,FXGLCYLINDER_SLICES_NUMBER,FXGLCYLINDER_LOOPS);
  glPopMatrix();
  gluDeleteQuadric(quad);
#endif
  }

Observe that we push the matrix, add a hard-coded rotation to the current 
matrix, paint the cylinder, and pop the matrix. The library therefor 
disables end-programmer control over the orientation of the cylinders 
available.

Also observe this is on the FOX side, not the FXRuby side.

I could go in after this myself, but first I must ask if the ability to set 
the rotation matrix as a property of the FXGLCylinder is a pending or 
near-term feature. I'm asking here on behalf of continuity with my prior 
posts, and with Lyle's maintenance of FXRuby, but I'm also asking on the 
FOX mailing list.

I have fox-0.99.174, but the source for fox-0.99.181 shows the same problem.

-- 
Phlip

http://www.greencheese.org/HatTrick