We present a novel technique for computing ambient occlusion (Akenine-Möller et al., 2008) on real-time graphics hardware. Our method approximates the occlusion for a local illumination model by introducing curvature-dependent function. Using our method, we are able to acquire occlusion at lower computational cost than conventional methods such as SSAO (Bavoil et al., 2008). Our method requires a multi-pass algorithm with the graphics processing unit (GPU). In the first pass curvature is acquired, and in the second pass the occlusion is computed from the curvature. In the calculating occlusion from the curvature, we approximate the geometric shape by a quadric surface function, and then obtain a curvature dependent function which is an approximation of geometric surface. This function depends only on local variables and we are able to calculate the ambient occlusion for the local illumination model. According to our results, both the computational and storage costs are sufficiently low for the technique to be applied to current graphics hardware supported computer games.