From: Phlip <phlip_cpp@...>
Date: 2001-12-02T16:19:36+09:00
Subject: [ruby-talk:27255] Is there a geometer in the house? (OpenGL Translate vs POVray Translate)

Newsgroupies:

Below my sig is a snip of RubyFX code attempting to drive OpenGL to make a 
Y shape.

The symptom is the numbers in POVray code make a Y, but the same numbers 
pushed onto OpenGL's stack of quads creates a VI symbol. It broke.

The POVray script looks like this:

 union {
 cylinder {<0,0,0>,<0,59.0625,0>, 3.32227
           pigment{col_2}
            finish  {ambient 0.3 diffuse 0.7 phong 1}
           rotate < 0, 0, -32.8296> rotate < 0, -99.4838, 0>
           translate < 0, 175, 0>}
 cylinder {<0,0,0>,<0,44.2969,0>, 1.86877
           pigment{col_2}
            finish  {ambient 0.3 diffuse 0.7 phong 1}
           rotate < 0, 0, -65.6593> rotate < 0, -99.4838, 0>
           translate < -5.31988, 222.175, 30.1705>}
 cylinder {<0,0,0>,<0,44.2969,0>, 1.86877
           pigment{col_2}
            finish  {ambient 0.3 diffuse 0.7 phong 1}
           rotate < 0, 0, -32.8296> rotate < 0, -99.4838, 0>
           translate < -5.31988, 222.175, 30.1705>}
}

Those brave enough to execute the Ruby snip below my sig (using 
FXRuby-0.99.181 -> fox-0.99.181 -> 2001/04/30 rbgl -> opengl) will see the 
three broken cylinders not joined at their branching point.

The variable xyzEnd is (in this context) not used. But notice it equals the 
xyzTranslate value of the V cylinders.

The POVray output transposes X and Y because POVray uses Z for "away from 
the viewer" while the input numbers (in the real app) use Z for "up". In 
the OpenGL system I did not deal with this, and left Z pointing towards the 
user.

I have tried various permutations of the orders of the Rotate and Translate 
calls, and of the order of X, Y and Z within them. No luck.

Any tips?

-- 
Phlip

#!/usr/bin/env ruby

require 'fox'
require 'opengl'
require 'fox/glshapes'
include Fox


class GLViewWindow < FXMainWindow

  ID_GLVIEWER = enum(FXMainWindow::ID_LAST, 1)[0]

  def initialize(app)
    super(app, "Bad Thing Test", nil, nil, DECOR_ALL, 0, 0, 800, 600)
    @mdiclient = FXMDIClient.new(self, LAYOUT_FILL_X|LAYOUT_FILL_Y)
    mdichild = FXMDIChild.new(@mdiclient, "FOX GL Viewer", @mdiicon,
      nil, MDI_MAXIMIZED, 30, 30, 300, 200)
    @glvisual = FXGLVisual.new(getApp(), VISUAL_DOUBLEBUFFER)
    @mdiclient.setActiveChild(mdichild)
    viewer = FXGLViewer.new(mdichild, @glvisual, self, ID_GLVIEWER,
      LAYOUT_FILL_X|LAYOUT_FILL_Y|LAYOUT_TOP|LAYOUT_LEFT)

    @scene = FXGLGroup.new
    gp2 = FXGLGroup.new
    @scene.append(gp2)
    

        addCylinder gp2, 59.0625, 3.322265625, 2, -32.82964323, 
-99.48376736, [0.0, 0.0, 175.0], [-5.319876145, 30.17051687, 222.1752194]

        addCylinder gp2, 44.296875, 1.868774414, 2, -65.65928646, 
-99.48376736, [-5.319876145, 30.17051687, 222.1752194], [-12.01231147, 
68.12520364, 239.3344216]
        
        addCylinder gp2, 44.296875, 1.868774414, 2, -32.82964323, 
-99.48376736, [-5.319876145, 30.17051687, 222.1752194], [-9.309783254, 
52.79840451, 257.556634]
    
    viewer.setScene(@scene)
  end


        def addCylinder gp, length,thickness,pigment,zeeRotation,whyRotation,
                 xyzTranslation, xyzEnd
                 
                exxTranslation, whyTranslation, zeeTranslation = xyzTranslation

        cyl = Cylinder.new ( exxTranslation, whyTranslation,
                                                zeeTranslation, length,  thickness )
          
                cyl.zeeRotation = zeeRotation
                cyl.whyRotation = whyRotation
                gp.append(cyl)
   
    end


  def create
    super
    show(PLACEMENT_SCREEN)
  end

end

def run
  application = FXApp.new("GLViewer", "FoxTest")
  application.disableThreads
  application.init(ARGV)
  GLViewWindow.new(application)
  application.create
  application.run
end


class Cylinder < FXGLCylinder
  def initialize(exxTranslation,
                        whyTranslation,
                        zeeTranslation,
                        length        , 
                        thickness     )
    super(0, 0, 0, length, thickness)
        @zeeRotation = 0
        @whyRotation = 0
        
        @exxTranslation, @whyTranslation, @zeeTranslation = 
                exxTranslation, whyTranslation, zeeTranslation
        
  end
  
  attr_writer :zeeRotation, :whyRotation
  
  def drawshape(viewer)
    quad = GLU::NewQuadric()
    GLU::QuadricDrawStyle(quad, GLU::FILL)
    GL::PushMatrix()


    GL::Rotate(@whyRotation, 0, 0, 1)
    GL::Rotate(@zeeRotation, 0, 1, 0)

        GL::Translate (
                @exxTranslation,
                @whyTranslation, 
                0 # @zeeTranslation,
                )
 
 # p [@exxTranslation, @whyTranslation, @zeeTranslation]

    GLU::Cylinder(quad, @radius, @radius, @height, SLICES_NUMBER, 
STACKS_NUMBER)
    
    #  XXX why all this was in the original?
    GLU::QuadricOrientation(quad, GLU::INSIDE)
    GLU::Disk(quad, 0, @radius, SLICES_NUMBER, LOOPS)
    GL::Translate(0, 0, @height)
    GLU::QuadricOrientation(quad, GLU::OUTSIDE)
    GLU::Disk(quad, 0, @radius, SLICES_NUMBER, LOOPS)
    
    GL::PopMatrix()
    GLU::DeleteQuadric(quad)
  end
end


run