Journal: Dr. Dobb's Journal Sept 1991 v16 n9 p127(7). ----------------------------------------------------------------------------- Title: 256-color VGA animation. (tutorial) Author: Abrash, Michael. AttFile: Program: GP-SEP91.ASC Source code listing. Summary: The third in a series of articles on the undocumented 320-by-240-pixel, 256-color VGA mode (called 'X-mode' by the author) develops a routine for copying a nonrectangular image from system memory to display memory. The 'masked copying' routine employs a rectangular bitmap that acts as a mask that corresponds to the transmitted image. The bitmap controls which pixels in the display are set according to the image and which are left alone. Another routine enables masked copies of images in one section of display memory to be rapidly copied to another four at pixels at a time through selection of appropriate image and mask pairs in off-screen display memory. A compact but powerful animation application is developed that utilizes the various capabilities of the X-mode. The program is based on a page-flipping concept, with animation movement achieved through transposal of pixels through masked copying. ----------------------------------------------------------------------------- Descriptors.. Topic: VGA Standard Functional Capabilities Programming Instruction Tutorial Animation Methods. Feature: illustration program. Caption: Mode X system memory-to-display memory masked copy routine. (program) Generates all four possible mode X image/mask alignments. (program) Sample mode X VGA animation program. (program)