Computer graphics processing and selective visual display system – Computer graphics processing – Graph generating
Reexamination Certificate
1999-02-25
2001-07-17
Hong, Stephen S. (Department: 2176)
Computer graphics processing and selective visual display system
Computer graphics processing
Graph generating
C345S440000, C345S473000
Reexamination Certificate
active
06262746
ABSTRACT:
BACKGROUND
This invention relates to blitting.
Multimedia programs and games often display animation on a computer screen using “sprites”. Sprites are “blitted” (short for “block transferred”) onto a background scene in a rapid sequence to create the illusion of motion. Blitting must be performed many times per second to create smooth animation. On occasion, many animation sequences are run simultaneously, which increases the computational load on the computer.
A first common method of performing blitting is to examine each pixel in the stored sprite and determine whether the pixel has the code for a transparent color. If not, the pixel is opaque, and is copied onto the background.
A second common approach is to create and save a sprite with white pixels in place of the transparent pixels along with a “mask” bitmap. The mask contains white pixels in place of transparent pixels, and black pixels in place of opaque pixels. When the sprite is to be displayed, the mask is ANDed with the background to create a resulting image with black pixels where the sprite will be located. This resulting image is then ORed with the sprite, to insert the sprite at the black pixels.
In addition to the above methods used in general purpose computers, some special purpose game machines, such as SEGA® and NINTENDO®, contain hardware to perform blitting very quickly.
SUMMARY
In general, in one aspect, the invention features a method of storing an image (e.g. a sprite) having transparent and non-transparent pixels. Data representing the values of the non-transparent pixels is stored, and each of at least some pixels are mapped to corresponding stored instructions.
Implementations of the invention may include the following features. Transparent pixels may be mapped to a first type of instruction, e.g. a command to skip pixels. Non-transparent pixels may be mapped to a second type of instruction, e.g. a command to copy pixels from a source to a destination. Groups of adjacent pixels may be mapped to single instructions. An edge of the image may be mapped to a corresponding stored instruction. The instructions may be machine-executable. The image may be scanned, a number of adjacent similar pixels counted, and an instruction which varies depending upon the counted number added to a queue when the type of pixel changes or when a row of pixels ends.
In general, in another aspect, the invention features a data structure including the values of non-transparent pixels, and an instruction queue holding instructions mapped from at least some of said pixels.
In general, in another aspect, the invention features a method of displaying a stored image by executing two types of instructions. A first type of instruction comprises a command to skip transparent pixels. A second type of command comprises a command to copy non-transparent pixels from source data representing non-transparent pixels.
Implementations of the invention may include the following features. A destination pointer may be incremented in response to a skip command. Data may be copied from a source to a destination in response to a copy command. The source pointer and a destination pointer may be incremented in response to the copy command. The skip command may increment the destination pointer by the number of transparent pixels in a contiguous group. The copy command may copy a number of pixels equal to a number of non-transparent pixels in a contiguous group.
The advantages of the invention include one or more of the following. More sprites may be stored in disk or memory. The sprites may be blitted to the computer screen of a general purpose computer extremely quickly, resulting in smoother animation. More animation sequences can be run simultaneously. Blitting may be performed without the use of jump (JMP) instructions.
Other features and advantages of the invention will become apparent from the following description and from the claims.
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Akin Gump Strauss Hauer & Feld & LLP
Compaq Computer Corporation
Hong Stephen S.
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