Frame buffer based transparency group computation on a GPU without context switching

Transparency groups or other images may be rendered on graphics hardware using a GPU utilizing only a single frame buffer and without the need to switch contexts to another frame buffer. A single frame buffer may be allocated and the overall background image may be rendered to the frame buffer. In order to render a foreground image to be combined with the background image, a sub-image of the background image is copied from the frame buffer to a texture atlas. The foreground image may then be rendered to the portion of the frame buffer from which sub-image was copied. The foreground image may then be copied from the frame buffer into the texture atlas. Additionally, both the sub-image of the background image and the foreground image may be merged and copied from the texture atlas into the frame buffer.