Is rectangle in scene?

[pabloarias]

Hello,

I'm working on an application where I build very big maps consisting of many square tiles each. Thus, I need to determine which tiles are currently visible by the camera, so that I don't load unnecessary textures. I don't want to construct an entity and a scenenode for a tile that is invisible, hence I can't check the current visibility by using usual methods (like node->isInScene()). The question is: given the middle point as vector and the length of each tile (a rectangle), how can I determine if it's visible by the current camera?

Thank you!

[puso1990]

hmm I never tried this but I think that this can be done with Ogre::Frustum. Camera is actualy a child of Frustum class and so it has:

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bool isVisible(const AxisAlignedBox& bound, FrustumPlane* culledBy = 0)

...method which I think might help you. You can get your SceneNode AABB with _getWorldAABB() I think.

Hope this helps someway

[pabloarias]

Thank you!

Yes I was trying to do something like that. The problem that I have is that I don't have a scenenode, because the object doesn't exist yet. I want to create the entity and the scene node after I have determined if the object is visible. The ideal thing would be to create an AABB of the object, an then use isVisible(). But I don't know how to construct such a bounding box with the information I have.

[puso1990]

As I said I haven't tried this myself but I think you could create new AxisAlignedBox set it's Minimum and Maximum corners (probably in world space, not sure) and test it against the frustum.

Or you can simply use frustums:

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bool isVisible(const Vector3& vert, FrustumPlane* culledBy = 0)

to simply check if a Vertex (in world space) is in Cameras frustum. Repeat this 4 times for each of the corners of the tile and I think should work

[pabloarias]

Thank you! It seems to be working!