1. A computer-implemented method comprising: providing a bitmap corresponding to a two-dimensional array of pixels; applying an object to the bitmap, using a processor configured to perform alpha channel operations, wherein said applying increments a value associated with a pixel touched by the object using an alpha channel operation to perform a blending of a source value with the value associated with the pixel, and the source value and a transparency value are defined such that the value is incremented by a fixed quantity upon said applying; and populating a two-dimensional array of values comprising the value.