Yes, it''s a lot easier with bounding spheres But I think the same trouble can occur at the beginnig of the frustum when it is thin.
Have you noticed it occurs at specific locations ? Being near the camera for example ?
And are you sur of your bounding spheres ? Try to draw them, and check if it is radius instead of -radius

ZMaster: I have exactly the same problem. The weird thing is that it's view dependent. If the camera an the object is positioned along the z-axis then there's no problem. If both the camera an the object is positioned along the x-axis then there's to cases.

1: If the camera looks along the x-axis then the objects disappear on the left side of the frustum.

2: If the camera looks along the negative x-axis then the objects disappear on the right side of the frustum. I use spheres as bounding volumes.

[edited by - __fold on September 5, 2003 7:02:07 PM]

Has anyone ever used Rectangle shapes and bounding boxes to check the frustum ?
I have modified the CubeinFrustum to do this, but it''s not working very well..

This is kindof in the other direction than the last posts, but: what would be faster, Frustum Culling, suing an octree, or putting the entire worldmesh into a display list. Or what if I manually divide the mesh up in say 4 parts (or 16 or whatever) using a 3D editor, and place em in display lists, and come up with a formula to check whether or not they are in the camera''s view?

By the way... how on earth am I supposed to do that (the checking if the camera sees it)? (I''m still a opengl newbie, and need all my time figuring out how to do the online part for now...)

Bruno: A simple rectangle/frustum check is this.

For all planes in the frustum.
{
  For all vertices i (Xi,Yi,Zi) in the rectangle
  {
    Calculate the distance by inserting the vertex in the plane
    (distance = A*Xi + B*Yi + C*Zi + D).
  }   
if all distances are positive
return outside
}
return inside.



[edited by - __fold on September 6, 2003 4:05:00 AM]

__fold, i believe that''s what i''m doing.
I test all points, accordingly to the size of the volume i''me feeding to the bounding box.., what''s wrong here ?


bool Camera::VolumeInFrustum( float x, float y, float z, float sizex, float sizey, float sizez )
{
for(int p = 0; p < 6; p++ )
{
if( frustum[p][0] * (x - sizex) + frustum[p][1] * (y - sizey) + frustum[p][2] * (z - sizez) + frustum[p][3] > 0 )
continue;
if( frustum[p][0] * (x + sizex) + frustum[p][1] * (y - sizey) + frustum[p][2] * (z - sizez) + frustum[p][3] > 0 )
continue;
if( frustum[p][0] * (x - sizex) + frustum[p][1] * (y + sizey) + frustum[p][2] * (z - sizez) + frustum[p][3] > 0 )
continue;
if( frustum[p][0] * (x + sizex) + frustum[p][1] * (y + sizey) + frustum[p][2] * (z - sizez) + frustum[p][3] > 0 )
continue;
if( frustum[p][0] * (x - sizex) + frustum[p][1] * (y - sizey) + frustum[p][2] * (z + sizez) + frustum[p][3] > 0 )
continue;
if( frustum[p][0] * (x + sizex) + frustum[p][1] * (y - sizey) + frustum[p][2] * (z + sizez) + frustum[p][3] > 0 )
continue;
if( frustum[p][0] * (x - sizex) + frustum[p][1] * (y + sizey) + frustum[p][2] * (z + sizez) + frustum[p][3] > 0 )
continue;
if( frustum[p][0] * (x + sizex) + frustum[p][1] * (y + sizey) + frustum[p][2] * (z + sizez) + frustum[p][3] > 0 )
continue;
return false;
}
return true;
}

There is an excellent article about quadtrees here at gamedev:
Quadtrees

it''s really worth looking at.

For object culling, you could use occlusion query. It's a method where you draw a bounding box to your object and ask the graphics card if the object is visible. In OpenGL you could use NV_occlusion_query or ARB_occlusion_query for example.

[edited by - ALiENiD on September 8, 2003 5:53:11 AM]

quote:Original post by ALiENiD
For object culling, you could use occlusion query. It''s a method where you draw a bounding box to your object and ask the graphics card if the object is visible. In OpenGL you could use NV_occlusion_query or ARB_occlusion_query for example.

[edited by - ALiENiD on September 8, 2003 5:53:11 AM]

More details please !