JPS595905B2 - Surface brightness generation method in display devices - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface brightness generation method for displaying a surface with continuous brightness changes within the surface when displaying a surface on a display device.

Conventional display devices, especially graphic display devices, mainly express shapes by displaying line segments, and do not display shapes as surfaces.

This is because, in the case of line segment display, the amount of data is small, ie, a vector between two points, and can be easily handled by a vector generator (using a digital differential analyzer, DDA, etc.). On the other hand, with the recent development of IC memory technology, it has become possible to configure a monitor display image memory (Video Frame Buffer) using a digital IC memory, and to perform high-resolution and high-speed display processing.

In a system in which the image memory is composed of a digital IC, the present inventors provide line segment data representing a closed loop that is the outline of a surface to be displayed, and depict all areas inside the closed loop with constant brightness. We have developed a surface image generation method that can control sweat retention on surfaces at high speed with extremely simple data processing, and have already filed a patent application for this method.
This invention further advances the above-mentioned plane image generation method,
This makes it possible to display more complex surfaces.

That is, while the previously proposed system expressed uniform brightness within one surface element, the present invention attempts to express continuous luminance changes within one surface element.
6-Generally, when an object expressed in a three-dimensional coordinate system (X, Y, Z) is expressed three-dimensionally on a two-dimensional CRT screen,
The display screen is assumed to be an X-Y plane, and data on the X and Y axes are expressed there, and data on the Z axis, which corresponds to the depth of the display screen, is expressed in terms of brightness (brightness is higher for points nearer to you, higher for points at the back). ).

Therefore, when displaying a plane of a certain shape as a plane, the plane may be expressed with uniform brightness as long as the plane is placed parallel to the display screen. However, when displaying a state in which the plane is tilted with respect to the display screen, the Z-axis data of each point on the plane is different, and it is desirable to change the brightness within the display pixel accordingly. The surface brightness generation method of the present invention allows such requirements to be quickly realized with a simple circuit configuration. This will be explained in detail below with reference to the drawings. First, an outline of a graphic display device to which the present invention is applied will be explained with reference to FIG.

This device includes a display processor 1, a DDA circuit 2, a memory control circuit 3, an image memory 4 for monitor display, and a C
It is composed of an RT monitor circuit 5, a surface generation image memory 6, and the like. The display processor 1 develops a display file provided by a host computer (not shown) to obtain original data necessary for generating straight lines, curves, or surfaces, including scaling, rotation, etc. The DDA circuit 2 is a circuit that calculates image data based on the original data obtained by the processor 1, and this circuit outputs image data expressed in three dimensions (X, YZ). The output data is written into the image memory 4 or 6 via the memory control circuit 3. The image memory 4 is composed of a digital IC memory, and for example, the screen of a CRT is 1024 x 102.
4 pixels (i.e. CRT
When displaying on the screen with a resolution of 1024 x 1024), 1024 x which corresponds two-dimensionally to each pixel array
The image memory 4 is composed of a plurality of memory planes having an array structure of 1024 memory cells.

The coordinate position (X
, Y address), and if multiple memory planes are used in parallel, multiple bits of information can be stored in each coordinate position. This allows image data with display brightness information to be stored.

In the illustrated example, the image memory 4 is composed of four memory planes 4a to 4d, can write 4 bits of information at each coordinate position, and can express 16 levels of brightness. The other image memory 6 has exactly the same configuration as the above, and is also composed of four memory brains 6a to 6d. In the present invention, when displaying a plane with a certain contour, closed loop data (a set of data representing minute straight lines) representing the contour of the surface image is provided, and each point on the contour is Provides data indicating display brightness.

In response to this, the DDA circuit 2 performs a predetermined calculation, and as the calculation progresses, the
-Coordinate value of Y plane (10-bit data for both X and Y)
Display brightness information (4
bit data (this is called Z data) is DD
The signals are sequentially outputted from the A circuit 2 at high speed. Note that the calculation of image data (line segment data) by such a DDA circuit is a known technique. The memory control circuit 3 supplies the X, Y coordinate values of the closed loop data (X, Y, Z) sequentially output from the DDA circuit 2 to the image memory 4 (or 6) as X, Y addresses. At the same time, Z data is input as write data. As a result, each Z data is stored in the image memory 4 (or 6) at a position corresponding to the X and Y coordinate values sequentially output from the DDA circuit 2. When displaying the stored contents of the image memory 4 on a CRT, the CRT monitor circuit 5 makes the raster scan of the CRT and the read scan of the image memory 4 correspond two-dimensionally and synchronizes them. The read data is used as a CRT brightness control signal. For example, if the above-mentioned closed loop data is written in the image memory 4 and is monitored by the CRT monitor circuit 5, the CR
A closed loop is drawn on the T screen by a line with continuous brightness changes. In this image, the surface is expressed only by the contour line, and the brightness changes representing the positional relationship of the surface in the z direction are also expressed only on the contour line. This is a common surface expression in the past. The surface brightness generation method of the present invention defines the inside of the closed loop by the brightness of each point on the closed loop when the closed loop data as described above is given and a surface display command for the closed loop is given. This is a method for generating such image data based on the closed loop data and writing it into the image memory 4 in order to perform a surface display filled with bright lines having brightness changes.

This method will be explained in detail below. First, DDA circuit 2
The above-mentioned closed lube data outputted from is written into the surface generation image memory 6, and then, as described below, the image memory 6 is sequentially scanned in a fixed direction to read out the closed lube data.

FIG. 2 schematically shows a state in which closed-loop data is written in the image memory 6. However, although luminance information is not written in the closed loop t in the figure, Z data is stored in the image memory 6. Assume that the image memory 6 has the X and Y axes (addresses) set as shown in the figure (the image memory 4 is exactly the same), and the scanning to read the closed loop data on the image memory 6 is in the X direction. And X-
It is assumed that the operations are performed sequentially from the upper left to the lower right on the Y plane. What is required in this scan, as will become clear in the following, is to detect two intersections between the scan line and the closed loop t in one scan, and to temporarily store the Z data at those intersections. There is no need to scan an area that does not have an intersection with the closed loop t, and a line that has one intersection with the closed loop t (a line that touches two vertices of the closed loop t).

Therefore, if the maximum and minimum x addresses of the closed loop data are set to XMAX and XMIN, and the maximum and minimum Y addresses are set to YMAX and YMIN, the readout scan of the image memory 6 is set to XMIN, XMAX and YMIN+1, YMA.
This is performed only for the address range surrounded by X-1. (
To do this, it is necessary to know the maximum and minimum addresses of the closed loop data. This is because when the DDA circuit 2 outputs a group of address information representing the closed loop, It is only necessary to detect and store the minimum value, and based on this, it is easy to control scanning of only a limited range as described above). If only the above range is scanned, two intersections with the closed loop t can always be detected for each scan. Although the explanation will be complicated, in order to satisfy this condition, a condition is naturally attached to the form of the closed loop t, and in the present invention, a closed loop that meets the condition is treated as an object of surface generation. As mentioned above, two intersection points with the closed loop t are detected every time the image memory 6 is scanned, and when a certain scanning line Yi is scanned, the first point detected in the scanning direction is The point detected next is called the first intersection point Pil and the second intersection point Qi.

Also, set the X, Y addresses of point P1 to X(Pi), Y(Pi)
), and the point PiO)Z data is called Z(Pi) (the same applies to point Qi). Now, in the present invention, the image memory 6
In the above closed-loop data, for example, if the luminance data of the two intersections Pi and Qi on the scanning line Yi are Z(Pi) and Z(Qi), respectively, then in the monitor display image memory 4, the point Pi2{X( On the line connecting the point Qi-{X(Q1), Yl} from
Luminance data that continuously changes from Pi) to Z(Qi) is written.

To explain specifically, in the image memory 6, Z(Pi
)=12, Z(Qi)=8, the difference is 4, and X(P
Assuming that i)-X(Qi)=100, the following luminance data is written in the image memory 4.

By the way, as mentioned above, the points Pi,
The brightness data of Qi is stored as Z(Pi) in the image memory 6.
, Z(Qi), it is most preferable, but in the present invention, the points Pi,Q in the image memory 4
The brightness data of i is Z(Pi) in the image memory 6,
Even cases where the value differs slightly from Z(Qi) are allowed.

The above data generation is realized, for example, by the following control means.

(a) When reading and scanning the image memory 6, the scanning address is also given to the image memory 4 to access it and put the memory 4 into a writing state.

(b) Regarding the intersection points Pi and Qi detected during scanning of the line Yi in the image memory 6, temporarily store X(Qi)-X(Pi)=ΔXi corresponding to the distance between the two points, and also store the second intersection point The brightness data Z(Qi) of Ql is temporarily stored.

((c) When scanning the next line Yi+1, if the first intersection Pi+1 is detected first, its luminance data Z(Pi
+1) is temporarily stored, and Z(Qi) - Z(Pi
+1) = ΔZi is calculated.

(d) When scanning the above line Yi+1, the first intersection Pi+
In the scanning process from 1 to the second intersection Qi+1, luminance data changes continuously from Z(Pi+1) to Z(Pi+1)+ΔZi in synchronization with the scanning clock at a rate of change corresponding to ΔXi/ΔZi. to occur.

(At the same time as (d), the luminance data sequentially generated in (d) is written into the image memory 4.

As a result, in the image memory 4, Z(Pi+1) to Z(Pi+1) are
Luminance data that continuously changes up to +I)+ΔZi is written.

By sequentially performing this control from YMIN+1 to YMAX-1, two vertices of the closed loop and YMIN of the area surrounded by the closed loop written in the image memory 6 are
The area of the image memory 4 corresponding to the entire area except the +1 line is filled with luminance data that loosely connects the luminances on the closed loop. This is surface image data, and when this is displayed via the CRT monitor circuit 5 as described above, a surface with a contour represented by the closed loop described above and a continuous luminance change is displayed on the CRT screen. It is depicted. In addition, as mentioned above, the two vertices of the closed rube and YMIN
Although data on the +1 line is missing, this is not a problem in practice. Also, YM
It is also easy to generate data for this line by scanning IN+1 twice. Third
The figure shows the main parts of the circuit for controlling (a) to (e) above. In the figure, ZOut indicates the 4-bit luminance data read out from the image memory 6; Zin indicates the luminance data to be written to the image memory 4.The area of the image memory 6 where the closed loop data is written is sequentially scanned as described above, and the scanning address is also given to the image memory 4.At this time, the image memory 6 memory 6 to 4
Each digit of the bit output ZOut is logically summed by an 0R gate G1, and the output thereof is input to a flip-flop FF. This flip-flop FF is 0R gate G1
is inverted at the rising edge of the output of , and is set when the first intersection point is detected during each scan of the image memory 6, and is set when the second intersection point is detected. Therefore, the set output Q of the flip-flop is during the scanning period 11I from the first intersection to the second intersection. The counter 10 is a flip-flop FF
While the set output Ql:)5"1" is set, the AND
A scanning clock CL is input through gate G2 and is counted.

When the reset output O of the flip-flop FF rises to 1, the count value of the counter 10 is latched in the register 11, and the counter 10 is then cleared. That is, the counter 10 calculates X(Ql)- for each scan.
X(Pi) is counted and the value is latched in the register 11. Also, the set output Q of the flip-flop FF is 11
When I rises, ZOutl, that is, Z(Pi), which is being output at that time, is latched in the register 12 and counter 14, respectively. When the set output Q rises to 11 again, ZOutl, that is, Z(Qi), which is being output at that time, is latched into the register 13. Therefore, it is now assumed that scanning of line Yi has ended and scanning of the next line Yi+1 has begun.

At this time, X(Pi)-X(Qi) is latched in the register 11, and Z(Qi) is latched in the register 13. Then, in scanning line Yi+1, the first intersection Pi+1
When Z is detected, register 12 and counter 14
(Pi+1) is set, the subtracter 15 calculates the value, and the value is supplied to the signed absolute value conversion circuit 16, where it is separated into the sign of 2 and IΔZil.

The sign signal becomes a signal for controlling up-counting and down-counting of the counter 14, and lΔZlI is read into a predetermined digit position of the register 18 via the selector 17. Note that X(Pi)-X(Qi) of register 11
The data is converted into a signal by the priority encoder 19, and the digit position at which lΔZiI is to be read into the register 18 is determined according to the upper value. The circuit section surrounded by dotted lines, including the counter 14, conversion circuit 16, etc., is a normal 1-axis vector generator 22 that uses a DDA integrator as a constant multiplier, and each time the scanning clock CL is input, In the adder 20, the contents of the register 18 and the register 21 are added and stored in the register 21 again, and the carry signal generated from the adder 20 during this calculation process becomes the up or down count input of the counter 14.

This operation is a general operation performed by a vector generator, and will not be described in detail. In short, by the calculation of the vector generator 22, the output of the counter 14 is changed to the first intersection point P
The preset Z(P
It continuously increases or decreases from i+1) to Z(Pi+1)+ΔZi at a uniform rate of change.

The output of this counter 14 is derived via AND gates G3 to G6 to which the set output Q of the flip-flop FF is applied as a gate signal, and becomes the luminance data Zin to be written into the image memory 4. Note that the above calculation can be performed not only by the illustrated vector generator 22 but also by vector generators of various types. By the way, in the circuit of FIG. 3, that is, the control in (a) to (e) above, P
In order to generate luminance data connecting from i+ to Qi+1, X(Pi+1), X(Q1+l), Z(Pi+1
), Z(Qi+1)...{I) (the scanning of line Yi+1 is
), the previous scanning line Y
Using the detection data at i, calculations are performed based on.

Therefore, the final value of the luminance data obtained by this calculation is 2, but the luminance data Z (Qi+1) on the image memory 6 is -
There may be cases where this is not possible.

However, the difference is so small that it does not pose a problem in practice. /． -αNaP4ZL. Akira Ishikawa) 17-pu, force'7,) is calculated and output by the DDA circuit 2, and the data on each axis X, Y, and Z shows continuous changes, respectively. In other words, the closed loop data is given so as to satisfy the following conditions. 〈≦Therefore, .

That is, based on the data of
When the luminance data connecting up to i+1 is calculated, even if there is an error between that luminance data and the data (calculated based on this), the difference is within 1 bit. For similar reasons, Pi+11) and Qi
In order to generate luminance data connecting up to +1, there is almost no problem even if calculations are performed using the above-mentioned y field 1.

Further, the control circuit therefor may be substantially the same as that shown in FIG. In the above explanation, the calculated luminance data is written to the image memory 4 while reading and scanning the image memory 6. However, the number of image memories is one, and an appropriate buffer circuit is provided along with it. If reading and writing of the memory is appropriately controlled, it is possible to sequentially write the calculated image data to the memory itself in parallel with sequentially reading the closed loop data written to the memory.

In addition, it was explained that when scanning the closed loop data written in the image memory 6, the range of the maximum and minimum addresses of the data is scanned, but as long as the intersection with the closed loop can be detected, it is necessary to scan outside the closed loop. However, if the scanning range is further reduced based on this idea, it will help speed up data processing. The surface brightness generation system according to the present invention has been described in detail above. According to this system, the logic of data processing is extremely simple, and the display of surface images with brightness changes, which has been difficult in the past, can be easily displayed. This can be done at high speed using circuits, greatly expanding the expressive capabilities of graphic displays.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a schematic configuration of a graphic display device to which the present invention is applied, Fig. 2 is an explanatory diagram of the method of the present invention, and Fig. 3 shows the main parts of a control circuit realizing the method of the present invention. FIG. 1...December processor 1, 2...
...DDA circuit, 3...Memory control circuit, 4
・・・・・・Image memory for monitor display, 5・・・・・・
CRT monitor circuit, 6... Image memory for surface generation.

Claims (1)

[Claims] 1 consists of digital IC memory, monitor screen and 2
In a display device using an image memory having a dimensionally corresponding memory cell array, surface image data to be displayed is provided as closed-loop data representing a contour line of the surface image and including brightness data of each point on the contour line, After writing the closed-loop data into the image memory, when sequentially reading and scanning the area of the image memory in which the closed-loop data has been written in a certain direction, the first detected line element of the closed-loop for each scanning line is calculated. If the first intersection point is the next detected line element of the closed loop, the second intersection point is the luminance between the first intersection point and the second intersection point detected in the scanning line immediately before the latest scanning line. Find the difference between
During subsequent scanning, luminance data that continuously increases or decreases by the difference in luminance obtained above, with the luminance of the first intersection as the initial value, from the time when the first intersection is detected to the time when the second intersection is detected. is generated in synchronization with scanning, and this luminance data is
By sequentially writing into the image memory or an image memory prepared separately to the positions specified by the scanning address at that time, each point with different brightness on the closed loop is connected by continuous brightness changes. A surface brightness generation method in a display device that generates surface image data by filling the closed loop with such brightness data.