Properly scale the the bounding sphere for frustum culling

The original radius must be squared too.  Also, negative distances mean
the sphere is inside the frustum and should not be culled.

diff --git a/source/scene.cpp b/source/scene.cpp
index 6c3d2910706db98d6f2ecd7ed67b3dd771c372e8..b8a74b59be7f3c6be74c85a179994c07345755ae 100644 (file)
--- a/source/scene.cpp
+++ b/source/scene.cpp
@@ -66,13 +66,13 @@ bool Scene::frustum_cull(const Renderable &renderable) const
                return false;
 
        Vector4 center = culling_matrix*(*matrix*compose(bsphere->get_center(), 1.0f));
-       Vector4 x_axis = *matrix*Vector4(1.0f, 0.0f, 0.0f, 0.0f);
-       float radius_sq = bsphere->get_radius()*inner_product(x_axis, x_axis);
+       Vector4 x_axis = *matrix*Vector4(bsphere->get_radius(), 0.0f, 0.0f, 0.0f);
+       float radius_sq = inner_product(x_axis, x_axis);
 
        for(unsigned i=0; i<6; ++i)
        {
                float distance = inner_product(center, frustum_edges[i]);
-               if(distance*distance>radius_sq)
+               if(distance>0 && distance*distance>radius_sq)
                        return true;
        }