pyopengl-users

[PyOpenGL-Users] A big problem with glOrtho

[projetmbc <pro...@cl...>]

I'm becoming crazy with the definition of the two last parameters of glOrtho.

My problem is that I would like to a box  with for example XMin=-12, XMax=12, YMin=-12, YMax=12 and ZMin=-5, ZMax=5. I do not understand how to do that simple thing such as nothing in the cube could disapear when manipulating with the mouse.

My problem is not how to draw the box but to define a view such as all the box will be always entirely visible.

Christophe.

Re: [PyOpenGL-Users] A big problem with glOrtho

[Ian M. <geo...@gm...>]

Definitely recommend using a perspective matrix for your first OpenGL
programs.  I use this class for perspective:

class glLibView3D():
    def __init__(self,rect,angle,near=0.1,far=1000.0):
        self.rect = list(rect)
        self.angle = angle
        self.near = near
        self.far = far
    def set_angle(self,value):
        self.angle = angle
    def set_near(self,value):
        self.near = value
    def set_far(self,value):
        self.far = value
    def set_view(self):
        glViewport(*self.rect)
        glMatrixMode(GL_PROJECTION)
        glLoadIdentity()
        gluPerspective(self.angle,float(self.rect[2])/float(self.rect[3]),\
        self.near,self.far)
        glMatrixMode(GL_MODELVIEW)
        glLoadIdentity()

HTH,
Ian

Re: [PyOpenGL-Users] A big problem with glOrtho

[projetmbc <pro...@cl...>]

Thanks for the information. Finally the problem was another  :-[  :
                GL.glEnable(GL.GL_CULL_FACE)

Where there are mathematic ( from the OpenGL's point of view) 
definitions of the different perspectives ?

Best regards and a great thanks for the help.
Christophe.


> Definitely recommend using a perspective matrix for your first OpenGL 
> programs.  I use this class for perspective:
>
> class glLibView3D():
>     def __init__(self,rect,angle,near=0.1,far=1000.0):
>         self.rect = list(rect)
>         self.angle = angle
>         self.near = near
>         self.far = far
>     def set_angle(self,value):
>         self.angle = angle
>     def set_near(self,value):
>         self.near = value
>     def set_far(self,value):
>         self.far = value
>     def set_view(self):
>         glViewport(*self.rect)
>         glMatrixMode(GL_PROJECTION)
>         glLoadIdentity()
>         
> gluPerspective(self.angle,float(self.rect[2])/float(self.rect[3]),\
>         self.near,self.far)
>         glMatrixMode(GL_MODELVIEW)
>         glLoadIdentity()
>
> HTH,
> Ian

Re: [PyOpenGL-Users] A big problem with glOrtho

[Dirk R. <dir...@gm...>]

	Hi Christophe,

projetmbc wrote:
> 
> Where there are mathematic ( from the OpenGL's point of view) 
> definitions of the different perspectives ?

you can get the actual matrices from the manpages 
(http://www.opengl.org/sdk/docs/man) or from the Redbook 
(http://www.opengl.org/documentation/red_book, Appendix F), which is a good 
resource to have when you're doing OpenGL anyway.

Yours

	Dirk

Re: [PyOpenGL-Users] A big problem with glOrtho

[projetmbc <pro...@cl...>]

Thanks a lot.

Christophe.



Dirk Reiners a écrit :
>
>     Hi Christophe,
>
> projetmbc wrote:
>>
>> Where there are mathematic ( from the OpenGL's point of view) 
>> definitions of the different perspectives ?
>
> you can get the actual matrices from the manpages 
> (http://www.opengl.org/sdk/docs/man) or from the Redbook 
> (http://www.opengl.org/documentation/red_book, Appendix F), which is a 
> good resource to have when you're doing OpenGL anyway.
>
> Yours
>
>     Dirk