A fast 2D frustum culling approach

By reducing the data amount to graph pipeline, the rendering efficiency can be improved significantly. We present a novel frustum culling approach (2D frustum culling) for the scene that has only one layer of objects, such as forest. This scene meets the condition `when projecting all the objects to one plane, the point on projected plane corresponds to only one object´. Our approach contains three parts. Firstly, derive the expression of frustum in object local space. Secondly, adopt double-queue to compute the largest convex polygon. Lastly, use scan algorithm to work out which points are in the convex polygon, and these points suggest according objects are within the view frustum. Rendering forest with such algorithm shows that it has good culling efficiency and meets real-time rendering requirements.