WO1990015381A1

WO1990015381A1 - System and method for video display object detection

Info

Publication number: WO1990015381A1
Application number: PCT/US1990/002992
Authority: WO
Inventors: David L. Needle
Original assignee: Atari Corporation
Priority date: 1989-06-02
Filing date: 1990-06-01
Publication date: 1990-12-13
Also published as: AU5824690A

Abstract

A hardware system (70) is used both to initiate processing information about an object for display when it is visible in the field of view of a display and to stop processing information about an object for display when that object is no longer visible in the field of view of the display. In operation, the system (70) monitors the activity of the actual display drawing circuits to notice if any pixel of a particular object is ever painted into the current display buffer. At the end of processing of this object, the flip-flop (90) will be ON if the object was NEVER painted into the display buffer. This NEVERON bit can later be examined by the software to decide whether or not this particular object needs further processing.

Description

SYSTEM AND METHOD FOR VIDEO DISPLAY OBJECT DETECTION

BACKGROUND OF THE INVENTION

1. Field of the Invention;

The present invention relates generally to a system and method for detecting whether or not a video object ever appears in a particular video window. More specifically, it relates to a hardware system and method for making this determination.

2. Description of the Prior Art; In many video display systems, the video objects that are displayed within a display window can be represented and manipulated independently of each other. This capability is common, for example, in video games. Part of this manipulation is usually the arbitrary positioning of the object anywhere within the display window, and i some systems, outside the display window. As a result o this arbitrary positioning, some part of the video objec may not be visible in the display window. At some poin in the life of this particular video object, it may b positioned such that NONE of it is visible in the displa window. When this happens, it is clear that any tim spent by the video system in preparing this object fo display was wasted.

In conventional video display systems, it is usuall the job of the display controlling software to pa attention to the position of objects, notice when they ar no longer visible in the display window, and avoid th wasteful processing of this non-visible object. While i is possible to monitor these events with software, doin so is expensive in terms of processing time. In addition if the video object is irregularly shaped, or if it boundaries are not easily discernable by the software, i becomes very difficult to decide if the object will b visible. It therefore would be desirable to have a way t discover if the object is visible without spending an software time, and without needing any software knowledg of the shape of the object.

SUMMARY OF THE INVENTION Accordingly, it is an object of this invention t reduce unnecessary processing of video objects for displa that are not visible in a video display as a result o their positioning.

It is another object of the invention to provide system and method for determining whether an object i visible in a video display without requiring software tim and without needing any software knowledge of the shape o the object.

It is another object of the invention to provide simple hardware system and method for determining whethe an object is visible in a video display.

The attainment of these and related objects may b achieved through use of the novel system and method fo video display object detection herein disclosed. system for video display object detection in accordanc with this invention has a settable memory element. means is connected to cause the settable memory elemen to assume one of its states at commencement of processin of a video object. A means is connected to the settabl memory element to cause the settable memory element t assume another of its states if a pixel of the vide object is ever painted. A memory stores a control block for the video object. A means is connected between an output of the settable memory element and the memory for writing information into the control block based on the state of the settable memory element.

The method for video display object detection includes causing a settable memory element to assume one of its states at commencement of processing of a video object. The settable memory element is caused to assume another of its states if a pixel of the video object is ever painted. A control block for the video object is stored. Information is written into the control bloc based on the state of the settable memory element.

The attainment of the foregoing and related objects, advantages and features of the invention should be mor readily apparent to those skilled in the art, after revie of the following more detailed description of th invention, taken together with the drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a perspective view of a system in whic the present invention is useful.

Figure 2 is a block diagram of the system shown i Figure 1. Figures 3A-3B are representations of video displa screens useful for understanding the present invention.

Figure 4 is a block diagram of a hardware system for video display object detection in accordance with th invention.

DETAIIiED DESCRIPTION OF THE INVENTION

Turning now to the drawings, more particularly t

Figure 1, there is shown a hand held electronic gam system 10 which utilizes the present invention to reduc the amount of memory storage required to define an process images, so that a conventional 6502 typ microprocessor can be used to provide real time, apparent perspective, graphics for a color liquid crystal display 12 used in the system 10. The system 10 includes conventional controls 14 and redundant sets 16 of buttons for firing weapons and similar functions. In use, the game system is grasped by handles 18 and 20 in the left and right hands, respectively, in the orientation shown. The redundant sets 16 of buttons allow the system 10 to be inverted for left hand operation of the buttons. When this is done, the orientation of the images on the display is flipped, so that it appears right side up when the sets 16 of buttons are on the left side of the system 10.

Those skilled in the art of graphics processing will appreciate the demanding memory and processing requirements for presenting real time, apparent perspective, color graphics with realistic motion on the display 12. In fact, most personal computers are unable to present such realistic, apparent perspective graphics with rapid enough motion to make games interesting. Usually, only arcade games presently have such capability. This is why the displays for most personal computer based video games are crude and are only two-dimensional. Conventional hand held electronic games have even cruder, monochrome graphics. The system 10 is even more remarkable in that the real time, apparent perspective, color graphics with realistic motion are achieved by usin a conventional 6502 type microprocessor, an earl microprocessor design that has been available since the late 1970s. The system and method for video displa object detection of this invention is one of th techniques used in the system 10 to make more efficien use of the 6502 microprocessor so that it is able t handle the graphics and other processing requirements fo the system 10. Figure 2 is a block diagram of electronics 30 for th system 10. A custom microprocessor integrated circuit 32 includes a standard 65C02 microprocessor CPU cell 34 and on chip interface and support circuits. The integrated circuit 32 is connected by a control bus 36 to a custom sprite engine integrated circuit 38, which also includes switch reader circuits for the switches 14 and 16 and read only memory (ROM) reader circuits for the ROM reader 40, included in the sprite engine integrated circuit 38 due to pin limitations on the microprocessor integrated circuit 32. The integrated circuit 32 is connected to a 64K x 8 random access memory (RAM) 42 by 8-bit address and data busses 44 and 46 and by a 3-bit RAM control bus 48. The RAM 42 houses the video buffer(s) and collision buffer i addition to the game software. The RAM 42 has a 120 nanosecond row address strobe (RAS) access time and 6 nanosecond page mode column address strobe (CAS) acces time. This allows a 250 ns (4 MegaHertz) page mod memory access rate and a 312 ns (3.2 MHz) normal memor access rate. The microprocessor integrated circuit 32 is connecte to the liquid crystal display (LCD) 12 by a 4-bit vide data bus 50 and an 11-bit video control bus 52. The LC has a resolution of 160 horizontal color pixels by 10 vertical color pixels. The column drivers for th display 12 can generate 16 levels of intensity for eac pixel, resulting in a palette of 4,096 colors. Th present invention avoids unnecessary processing o information about video objects that are not visible o the display 12. For purposes of this application, th remaining elements shown in Figure 2 are conventional i nature, and they therefore will not be described further.

Figure 3A shows a display image frame 50 for representative video game, in this case a bicycle trac racing event, as the image 50 appears on the display 12 Racers 52 and 54 are located well within the field of vie of the frame 50. Racer 56 has just entered the field o view of the frame 50, and racer 58 is just about to leave the field of view of the frame 50. Because the four racers 52-58 are wholly or partly within the field of view of the frame 50 on the display 12, the video system 30 must spend processing time to prepare these objects for display in the frames for which they remain visible on the display 12.

Racers 60 and 62 are positioned outside the field of view of the frame 50, in the positions relative to the frame 50 that they would occupy if visible in the frame 50. Any processor time spent to prepare these objects fo display would therefore be wasted.

Figure 3B shows a subsequent frame 64 as it woul appear on the display. Racer 58 has moved out of th field of view of the frame 64, and racer 60 has now jus entered the field of view. The processor should therefor begin processing information about the racer 60 fo display, and no longer be processing information about th racer 58 for display. Figure 4 shows a hardware system 70 which is use both to initiate processing information about an objec for display when it is visible in the field of view of display and to stop processing information about a object for display when that object is no longer visibl in the field of view of the display. A comparator 7 receives pixel addresses 74 and screen boundaries 76 a inputs on lines 78 and 80. Output 82 of the comparator i one input to AND gate "84. The other input to AND gate 8 is a paint each pixel command signal on line 86. Outpu 88 of the AND gate 84 is connected to the set input o flip-flop 90. A start painting object signal is supplie on line 92 to the reset input of flip-flop 90. When th flip-flop is set, it produces a NEVERON signal on line 9 as its output. The NEVERON signal is supplied as the input to flip-flop 94, the Q output of which is connecte to memory 42. A done painting signal on line 96 clear the flip-flop 94.

In operation, the system 70 monitors the activity of the actual display drawing circuits to notice if any pixel of a particular object, such as the racers 52-62 i Figures 3A and 3B, is ever painted into the curren display buffer. This is done by setting the flip-flop 90 at the start of processing of a video object, and clearin the flip-flop 90 if a pixel is ever painted. At the en of processing of this object, the flip-flop will be ON i the object was NEVER painted into the display buffer. This bit of information (the NEVERON bit) is then sent t the control block for that particular video object, an the next object is similarly processed. This NEVERON bi can later be examined by the software to decide whether o not this particular object needs further processing. I not, it can be dropped from the system 30.

It should now be readily apparent to those skilled i the art that a novel system and method for video displa object detection capable of achieving the stated object of the invention has been provided. The system and metho for video display object detection reduces unnecessar processing of video objects for display that are no visible in a video display as a result of thei positioning. The system and method determines whether a object is visible in a video display without requirin software time and without needing any software knowledg of the shape of the object. This simple hardware syste and method determines whether an object is visible in video display. It should further be apparent to those skilled in th art that various changes in form and details of th invention as shown and described may be made. It i intended that such changes be included within the spiri and scope of the claims appended hereto.

Claims

WHAT IS CLAIMED IS:

1. A system for video display object detection, which comprises a settable memory element, means connected to said settable memory element to cause said settable memory element to assume one of its states at commencement of processing of a video object, means connected to said settable memory element to cause said settable memory element to assume another of its states if a pixel of the video object is ever painted, a memory for storing a control block for the video object, and means connected between an output of said settable memory element and said memory for writing information into the control block based on the state of said settable memory element.

2. The system for video display object detection of Claim 1 in which said settable memory element is a flip- flop circuit.

3. The system for video display object detection of Claim 2 in which said means connected to cause said settable memory element to assume one of its states is configured and connected to set said flip flop circuit.

4. The system for video display object detection of Claim 3 in which said means connected to said settable memory element to cause said settable memory element to assume another of its states is configured and connected to clear said flip-flop circuit.

5. The system for video display object detection of Claim 1 in which said means connected to said settable memory element to cause said settable memory element to assume one of its states comprises means for comparing a pixel address of the object with screen boundaries for the video display and means for logical combination of an output from said means for comparing with a signal for painting a pixel, an output of said means for logical combination being connected to said settable memory element.

6. The system for video display object detection of Claim 5 in which said means for logical combination is an AND gate.

7. A method for video display object detection, which comprises causing a settable memory element to assume one of its states at commencement of processing of a video object, causing the settable memory element to assume another of its states if a pixel of the vide object is ever painted, storing a control block for th video object, and writing information into the control block based on the state of the settable memory element.

8. The method for video display object detection o Claim 7 in which the settable memory element is caused t assume one of its states by comparing a pixel address o the object with screen boundaries for the video displa and logically combining a result of the comparing with signal for painting a pixel, the settable memory elemen being caused to assume the one of its states by a resul of the logically combining.

9. The method for video display object detection o Claim 8 in which the logically combining is an AN operation.