JP2787497B2 - Graphic drawing method and apparatus - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a graphic drawing method and apparatus, and more particularly, to a graphic drawing method and apparatus suitable for displaying a minimal figure.

[Conventional technology]

Conventionally, for the method of dot-expanding and displaying figures such as straight lines and characters on raster graphic displays, see JD
In a document titled "Computer Graphics" by Foley / A.VAN DAM (Japan Computer Association, issued in July 1984), in order to perform dot development of line segments, the inclination of line segments was used and the computation overhead was reduced. Reduced algorithms are discussed. A typical example is Bresenham's algorithm,
These algorithms require at least the start and end points to be calculated, no matter how short the line segment.

An example of displaying a graphic on a display using the conventional method will be described with reference to FIGS. 3A, 3B, and 4. FIG.

In FIG. 4, a memory 1 stores graphic data defining the shape of a graphic that the user wants to display. The coordinate space of the graphic data is usually larger than the size of the dot map memory 3 so that the user does not need to be aware of the bit map memory. The display control device 2 reads the graphic data in the memory 1, performs coordinate conversion for enlarging / reducing and translating the coordinate values, converts them into the coordinates of the bitmap memory, and then develops them into dots using the above-described raster algorithm. Then, the data is written to the bit map memory 3. The contents of the bitmap memory 3 are converted into analog signals by a digital / analog converter 4 and displayed on a display 5.

The operation of the conventional system will be described in more detail with reference to FIGS. 2A and 2B. In FIG. 2A, the number of vertices = 3 as the graphic data 11
Is defined, and each vertex coordinate is P
₁ (0,0), P ₂ (4,6), P ₃ (8,0). When this figure is subjected to coordinate transformation with the enlargement magnification = 5, the translation amount being 300 in the x direction, and 500 in the y direction, the display control device 2
Perform coordinate transformation for each vertex, and P ₁ (300,500), P ₂ (32
0,530) and P ₃ (340,500), and dot development is performed by a raster algorithm so as to connect these vertices.

In FIG. 2B, for the same graphic data as in FIG. 2A,
The enlargement magnification = 1, the translation amount indicates a case where the same coordinate conversion is performed, and the converted vertex coordinates P ₁ (300,500), P
₂ (304,506) and P ₃ (308,500).

In many graphic systems, in order to process enlargement / reduction and parallel movement at high speed, it is necessary to change the magnification of coordinate transformation and the amount of parallel movement without changing the contents of the graphic data in the memory 1. Such a configuration is adopted.

FIG. 3A shows an example in which a line connecting P ₁ , P ₂ , and P ₃ in the example of FIG. 2B is dot-developed on the bitmap memory 3.

As described above, conventionally, coordinate conversion is performed for each vertex, and dot development is performed on the bitmap memory 3 by using a raster algorithm for a line segment connecting the vertexes.

[Problems to be solved by the invention]

In the above-described conventional method, coordinate conversion and dot development are performed on all vertices in any case, so that in the following cases, the calculation time is wasted.

FIG. 3B shows an example in which dots are developed when the enlargement ratio is 0.05 in the examples of FIGS. 2A and 2B. In this case, the converted vertex coordinates are P ₁ (300,500) and P ₂ (300.2,5
00.3), but if rounded to the nearest integer, P
₂ (300,500), and P ₁ and P ₂ match. Similarly P
₃ also becomes (300,500), the three vertices are displayed only on one dot as a result, and the same dot is drawn three times, and the coordinate conversion of the vertices P ₂ and P ₃ and the dot The computation time of the expansion was wasted.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce useless calculation time when a figure is displayed at a minimum.

[Means for solving the problem]

The object of the present invention is to provide a graphic drawing method in which two-dimensional or three-dimensional graphic data is dot-developed in a bitmap memory of a raster graphics display and the data developed in the bitmap memory is displayed on a screen. A step of determining whether the number of vertical and / or horizontal dots after expansion is larger or smaller than a predetermined determination reference value before developing the dimensional graphic data into the bitmap memory; And sometimes a procedure for developing the dots without using a raster algorithm.

The above-mentioned problem also involves that the graphic data includes data representing the size of the graphic on the graphic definition plane or the size on the bitmap memory, and the data has the number of vertical and / or horizontal dots after expansion. The present invention is also achieved by the graphic drawing method according to claim 1, which is used for determining whether the value becomes larger or smaller than a predetermined determination reference value.

The above-mentioned problem also includes a procedure for obtaining coordinates defining a minimum rectangle circumscribing the graphic to be displayed, and the number of vertical and / or horizontal dots after expansion is larger or smaller than a predetermined determination reference value. The method is also achieved by the graphic drawing method according to claim 1, wherein the determined coordinates are used to determine whether or not to be true.

The above object is also achieved by a memory for storing graphic data, and a first arithmetic means connected to the memory for performing coordinate conversion and / or translation of the graphic data and then developing dots on a bitmap memory using a raster algorithm. A display control device, a bitmap memory connected to the display control device, and a display connected to the bitmap memory via a D / A converter and displaying data developed in the bitmap memory as an image And a device for calculating a size of a graphic defined by the graphic data on a bitmap memory, wherein the calculated size is predetermined. Size determining means for comparing whether the value is larger or smaller than the determined reference value, and contacting the size determining means. Second calculating means for moving the graphic data coordinate conversion and or parallel to, the second
A third calculating means connected to the calculating means, and developing the calculation result of the second calculating means directly on the bitmap memory in dot form, wherein the first calculating means determines that the size determining means is large. The second and third calculation means are also achieved by a graphic drawing apparatus configured to perform the calculation when the size determination means determines that the size is small.

[Action]

Before the graphic to be displayed is developed as dot information in the dot information storage means (bitmap memory), the size represented by the number of dots when the graphic is developed as dot information in the bitmap memory is It is calculated. The calculated size is compared with a determination reference value to determine which is larger. The criterion value is set on the screen of the image display means, for example, based on the maximum number of dots recognized as a single point by human eyes.

If the calculated size of the figure is larger than the determination reference value, dot development is performed using a raster algorithm as in the past. On the other hand, when the calculated size of the figure is smaller than the determination reference value, the figure is recognized by the human eye only as one point when displayed on the screen, for example. In this case, the graphic is written on the bitmap memory as one dot without performing dot development using the raster algorithm.

By providing information indicating the size of the figure, for example, the size information of a rectangle circumscribing the figure in the figure data, the size can be calculated easily and in a short time. 3
In the case of a three-dimensional figure, for example, the size information of a rectangular parallelepiped circumscribing the figure may be provided instead of the rectangle.

Embodiment An embodiment of the present invention will be described below with reference to figures. FIG. 1 shows a configuration of a main part of a drawing apparatus according to a first embodiment of the present invention, a memory 1 for storing graphic data, a display control device 2 connected to the memory 1, and a display control device. 2, a bitmap memory 3 connected to
A D / A converter 4 connected to the bitmap memory 3,
And a display 5 connected to the output side of the D / A converter 4.

The display control device 2 includes a graphic length calculation block 211 connected to the memory 1, a coordinate conversion block 212 connected to the graphic length calculation block 211, and a coordinate conversion block 2.
12, a size determination block 213, a coordinate transformation block 221, a translation block 222, which are connected in series to the size determination block 213 and form a first calculating means.
Dot development block 223 and the size determination block 213
And a coordinate transformation block 231 and a parallel movement block 232 connected in series and forming a second calculation means, and a dot development block 233 connected to the parallel movement block 232 and forming a third calculation means. In. Dot development block 2
The outputs of 23 and 233 are connected to the bitmap memory 3.

The figure length calculation block 211 and the coordinate conversion block 212 form a unit for calculating the size of the figure on the bitmap memory, and the size determination block 213 forms a size determination unit.

The shape of the graphic displayed on the display 5 is stored in the memory 1 as graphic data. FIG. 5 shows a configuration example of the graphic data. The figure data includes, at a minimum, information indicating the type of the figure (circle, straight line, character string, etc.), shape numerical data for specifying the shape, and a minimum rectangular area (a figure existing Area) information is included. For example, if the shape numerical data is a circle, the center point position P
Coordinates and radius. The shape of the shape numerical data does not need to match the content described in the present embodiment,
What is necessary is that the content defined by the user is uniquely displayed on the display 5. For example, in the case of a circle, instead of having the above-mentioned data, it may be held as information on some straight lines approximating the circle.

The figure existence area is usually stored as the coordinate values of two vertices A ₁ and A ₂ . In this way, the memory for storing this information may be several bytes, and if the virtual storage method is used, the address space can be used up to several gigabytes, so that this does not pose a problem. This information is also used as a means for speeding up a graphic picking process (a process of detecting graphic data present at a designated coordinate position) and a clipping process (a process of drawing only a graphic present in a designated area). Is known to be effective. The creation of this information is, for example, in the case of a circle, A ₁ (x) = P (x) −γ, A ₂ (x) = P (x)
+ Γ, A ₁ (y) = P (y) −γ, A ₂ (y) = P (y) +
Since only simple addition with γ is sufficient, there is no problem as overbed.

The display control device 2 reads the graphic data from the memory 1, and first obtains the lengths of the entire graphic in the X and Y directions in a graphic length calculation block 211. Hereafter, P ₁ , P ₂ ,
A description will be given using a polygonal line having three vertices P ₃ as an example.
The size of this figure is obtained from the figure existence areas A ₁ and A ₂ by the following equation.

(Size in X direction) = A ₂ (x) −A ₁ (x) (1) (Size in Y direction) = A ₂ (y) −A ₁ (y) (2) In the next coordinate transformation block 212, the number of dots on the bitmap memory, which is obtained by the size obtained in the above, is obtained by the following equation. The magnification of the coordinate conversion is M.

(Size in the X direction on the bitmap memory) = (size in the X direction) × M (3) (size in the Y direction on the bitmap memory) = (size in the Y direction) × M ... (4) The size in the bitmap memory obtained by the above equations (3) and (4) is compared by the size determination block 213 with a predetermined determination reference value n dots, and the obtained bit If the size on the map memory is larger, the coordinate conversion block 221, the translation block 22
After 2, the dot development using the raster algorithm is performed in the dot development block 223.

On the other hand, (3), (4) the size of the bit map memory obtained in expression, if the determination reference value n is less than dots, the coordinate conversion block 231 for vertex P _1, coordinate transformation in translation block 232 Is performed, and at the obtained coordinate position,
The n dot writing is performed without using the raster algorithm. In this way, the coordinate conversion processing for the vertices P ₂ and P ₃ and the overhead of applying the raster algorithm to P ₁ , P ₂ and P ₃ are omitted. The effect of this omission is
The larger the number of vertices, the larger. Normally, the determination reference value n dots is set to a dot length that can be recognized by a human as only one lump due to the length per dot and the characteristics of the display (printing) device. For example, one dot is about 0.2mm
In the bitmap display of, even if it is one dot or two dots, there is also a problem of blur on the tube surface, and it looks almost the same. In such a case, it is better to set the criterion n = 2,
The probability that the conventional raster algorithm is not used increases, and the effect of the present invention is more exhibited.

Next, a second embodiment will be described with reference to FIG. In the present embodiment, a size determination block 216 is provided instead of the coordinate conversion block 212 and the size determination block 213 of the embodiment shown in FIG.
Is connected to a size determination reference value buffer block 215,
A criterion value calculation block 214 is connected to the size criterion input buffer block 215. Since the portion after the size determination block is the same as the embodiment shown in FIG.
Illustration and explanation are omitted. In the embodiment shown in the figure, the inverse conversion of the enlargement magnification M is performed in the determination reference value calculation block 214 for the determination reference value n dots, and the n dots on the bitmap memory 3 correspond to the coordinate space defining the graphic data. Is used to calculate the size. The calculated magnitude of n (n inverse transform value) is stored in the magnitude determination reference value buffer block 215. This value is a criterion value n
Alternatively, the calculation is performed only when the coordinate conversion magnification M is changed, and it is not necessary to calculate each time each figure data is read. Therefore, the calculation overhead is reduced as compared with the case of the embodiment shown in FIG. In the size determination block 216, the size (length) of the figure in the coordinate space in which the figure data is defined is compared with the n inverse transform value stored in the size determination reference value buffer block 215. After that,
This is the same as the first embodiment.

Next, a case where the present invention is applied to a three-dimensional figure will be described with reference to FIG. In the case of three dimensions, the basic configuration of the graphic data remains unchanged, and the type of the graphic (sphere, three-dimensional line,
(Dimension character string, etc.), shape numerical data, and a figure existence area. The vertex coordinates of the shape numerical data are three-dimensional coordinates. In addition, the figure existence area has an x coordinate,
y coordinates are stored as vertex A ₁ given by the minimum value of the z coordinate in the vertex A ₂ given by the maximum value, respectively.

As described above, the difference between the case of handling a two-dimensional figure and the case of handling a three-dimensional figure is only whether or not each vertex coordinate includes a z-axis coordinate value. The result is compared with the determination reference value, and the structure of changing the dot development method depending on which is larger may be the same as that of the two-dimensional figure.

FIG. 8 shows a main configuration of a graphic processing apparatus using the drawing apparatus shown in FIG. The illustrated graphic processing apparatus includes input means 81 for inputting data such as numerical values for generating and converting graphic data and coordinate instructions, and graphic data connected to the input means 81 for generating graphic data in accordance with the input data. Generating means 82, connected to the graphic data generating means 82,
Graphic data storage means 83 for storing the generated graphic data
And a display control device 85 connected to the graphic data storage means 83 for dot-expanding a graphic to be displayed in accordance with the input instruction, and connected to the display control device 85 for temporarily storing the dot-expanded graphic data. A dot information storage means (bit map memory) 86; a dot information display means (CRT display) 87 which is provided connected to the dot information storage means 86 and displays on a screen the dot information stored in the dot information storage means 86; , Is configured. Graphic data storage means 83 and graphic data generation means
A graphic data storage means 84 is connected as an auxiliary storage device. The display control device 85 is
This corresponds to the display control device 2 shown in the figure, and its internal configuration is represented by the coordinate conversion means 85A and the dot development means 85B.

According to the present embodiment, the graphic data generated by the graphic data generating means 82 based on the data input to the input means 81 or the graphic data stored in the graphic data storing means 84 is read out. The graphic data processed by the graphic data generating means 82 is stored in the graphic data storage means 83. The display control device 85 includes a graphic data storage unit.
The graphic data 83 is read, dot-expanded in the same procedure as described in the first embodiment, and output to the bitmap memory 86. The dot information display means 87 displays the dot information stored in the bitmap memory as an image on a display screen.

According to the present embodiment, when the graphic data is developed into dots, the size of the displayed image is confirmed in advance,
If the size is smaller than the predetermined size, the conversion procedure using the raster algorithm is omitted, so that the time from the input of the instruction by the device operator to the display of the image is reduced, and the image processing work is made more efficient. At the same time, there is an effect of reducing the frustration due to the delayed response in the online image processing operation.

〔The invention's effect〕

According to the present invention, before the graphic is developed into dots, the size when the graphic is developed into dots is determined, and when the size is smaller than a predetermined reference value, the raster algorithm is used. Is omitted, and the dot development is directly performed in the bitmap memory, so that unnecessary calculation time when displaying the minimal figure on the screen is eliminated, the drawing time is shortened, and the response of the apparatus is accelerated. effective.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a main part of a first embodiment of the present invention, FIGS. 2A, 2B, 3A and 3B are plan views showing a drawing example according to the prior art, and FIG. FIG. 5 is a block diagram showing an example of the configuration of graphic data according to the present invention; FIG. 6 is a block diagram showing a main part configuration of a second embodiment according to the present invention; FIG. 8 is a block diagram showing a main configuration of a graphic processing apparatus according to the present invention. 1 ... Memory, 2,85 ... Display control device, 3 ...
Bit map memory, 4 ... D / A converter, 5 ... Display device, 81 ... Input means, 82 ... Graphic data generation means, 83 ... Graphic data storage means, 86 ... Dot information storage means, 87 ... dot information display means, 211, 212 ... means for calculating the size of the figure, 213 ... size determination means, 221, 2
22,223... First arithmetic means, 231,232... Second arithmetic means, 233... Third arithmetic means.

Claims (4)

(57) [Claims] 1. A graphic drawing method in which two-dimensional or three-dimensional graphic data is dot-developed in a bitmap memory of a raster graphics display and the data developed in the bitmap memory is displayed on a screen. A step of determining whether the number of vertical and / or horizontal dots after expansion is larger or smaller than a predetermined determination reference value before developing the dimensional graphic data into the bitmap memory; Sometimes performing the dot development without using a raster algorithm. 2. The graphic data includes data representing the size of the graphic on a graphic definition plane or the size on a bit map memory, and the data defines the number of vertical and / or horizontal dots after expansion. 2. The graphic drawing method according to claim 1, wherein the method is used to determine whether the value is larger or smaller than the determined reference value. 3. A method for determining coordinates defining a minimum rectangle circumscribing a graphic to be displayed, wherein whether the number of vertical and / or horizontal dots after expansion is larger or smaller than a predetermined determination reference value. 2. The graphic drawing method according to claim 1, wherein the determined coordinates are used to determine. 4. A memory for storing graphic data, and first arithmetic means connected to the memory for performing coordinate conversion and / or translation of the graphic data and then developing dots on a bitmap memory using a raster algorithm. A display control device, a bitmap memory connected to the display control device, and a display device connected to the bitmap memory via a D / A converter and displaying data developed in the bitmap memory as an image. ,
Wherein the display control device calculates a size of a graphic defined by the graphic data on a bitmap memory, and determines that the calculated size is predetermined. Size determining means for comparing whether the value is larger or smaller than a reference value, second calculating means connected to the size determining means for performing coordinate transformation and / or parallel translation of the graphic data, and connected to the second calculating means And a third calculating means for directly developing the calculation result of the second calculating means in a dot map memory on a bit map memory basis, wherein the first calculating means performs a calculation when the size determining means determines that the size is large. Wherein the second and third calculation means are configured to perform calculation when the size determination means determines that the size is small.