[PyOpenGL-Users] culling with tétrahedron

[Roland E. <r.e...@gm...>]

Hi,

I am currently trying culling with a tetrahedron, but when I make it 
spin, some vertices disappear while they shouldn't, following the point 
of view of the camera.

Below is the code of the class I use to handle the object:

class Tetrahedron(Polyhedron):

     def __init__(self, size):

         self.vertices = [0.0, 0.0, float(size),
                          (float(size))*math.sin(120), 0.0, 
-(float(size))*math.cos(120),
                          -(float(size))*math.sin(240), 0.0, 
-(float(size))*math.cos(240),
                          0.0, float(size), 0.0]
         self.indices = [0, 1, 2,
                         0, 3, 2,
                         0, 3, 1,
                         1, 3, 2]

         Polyhedron.__init__(self)

     def render(self):

         glPolygonMode(GL_FRONT_AND_BACK, GL_LINE)
         glEnableClientState(GL_VERTEX_ARRAY)
         glVertexPointer(3, GL_FLOAT, 0, self.vertices) # Specify the 
vertex list to be used to draw the object

         glEnable(GL_CULL_FACE)
         glCullFace(GL_BACK)

         glColor3f(*self.color)
         glTranslatef (*self.position)
         glRotatef (self.x_angle, 1.0, 0.0, 0.0)
         glRotatef (self.y_angle, 0.0, 1.0, 0.0)
         glRotatef (self.z_angle, 0.0, 0.0, 1.0)
         glScalef (*self.scaling)

         glDrawElements(GL_TRIANGLES, 12, GL_UNSIGNED_BYTE, self.indices)

         glDisable(GL_CULL_FACE)

         glDisableClientState(GL_VERTEX_ARRAY)



What am I missing?

I did not face that problem with a Cube using the same code for method 
render (except for 1st and 2nd parameters of glDrawElements)

The superclass polyhedron only contains the variables used for the 
transformation and a few convenience method to set them.

I am running the code on Linux AMD 64 with pygame to get the window and 
interacting with the user.

Thanks for your help,


Roland.