JPH0883350A - Graphic display device - Google Patents

Abstract

PURPOSE: To guarantee the plotting result of a triangle with a peripheral line for an outer peripheral pattern other than solid lines by allowing a plotting processing part to plot and display boundary data generated by a hollow line processing part and peripheral lint data generated by an outer peripheral line processing part under the control of a boundary data controlling part. CONSTITUTION: The boundary data controlling part 21a manages the vertex coordinate values of a triangle and sends the absolute minimum numbers of triangle vertex coordinate values for the boundary of the triangle to a plotting data exchanging part 3 as graphic data. In this case, DDA processing for generating a boundary is the same DDA processing as that of an outer peripheral line. The sent boundary data are regarded as the triangle data of a triangle whose inside is hollow, hollow line processing is executed and the boundary is plotted by the same area color as that of the inside area of the triangle. When the pattern data of an outer peripheral line processed by the same DDA processing are plotted so as to be superposed to the boundary, the outer peripheral line on which a part of the boundary is left as the area color of the boundary can be plotted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes at least a triangle clip processing section for forming a triangle clipped by a window set on a display surface, a peripheral wire retraction processing section, a hollow wire processing section and a peripheral line processing section. In a graphic display device equipped with a DDA processing unit provided, a drawing data conversion unit for converting drawing data into dot data, and a drawing processing unit for performing actual drawing, three vertex coordinate values represented by a device coordinate system (DC) are displayed. It is divided by the scan conversion unit provided in the DDA processing unit from the triangle data that it has and the border line data that has the outer peripheral line portion of the triangle as a border line and that has a flag that indicates whether or not to draw the border line. The internal data (span data) of the triangular area of the device coordinate system (DC) and the boundary line data in which the boundary line adjacent to this is drawn as a hollow line are formed. In the drawing the peripheral line data, and overwrites the boundary line relates to graphic display device for displaying by drawing the triangle.

[0002]

2. Description of the Related Art FIGS. 10 to 14 are views for explaining a conventional method and apparatus for drawing a triangle with a peripheral line.
Shows an example of the configuration of a conventional graphic display device.
2 shows a conventional triangle surface-applied triangle surface painting method, FIG. 13 shows the difference between the triangle (area) DDA and the outer circumference line DDA, and FIG. 14 shows an example of storing triangular data.

Generally, as shown in FIG. 10, a graphic display device usually has at least a triangle clip processing unit 1, which forms a triangle clipped (framed by a window frame) in a window set on the display surface. Scan conversion unit 20 that draws the internal area (span) of the triangle, peripheral line retraction processing unit 20a, and hollow line processing unit 21
A DDA processing unit 2 including a peripheral line processing unit 22 and a drawing data conversion unit 3 for converting drawing data into dot data,
A drawing processing unit 4 for performing actual drawing is provided, and based on an instruction from an application program executed by a higher-level device (not shown),
Draw and display a triangle.

Here, the triangle clip processing unit 1 is
For example, when a triangular figure to be displayed is clipped in a window frame designated by a higher-level device (not shown), only the clipped figure (for example, triangle) is
This is a part for performing clip processing for displaying in the window.

The outer peripheral line retraction processing unit 20a also receives trigonal system data (for example, refer to the triangle vertex data list shown in FIG. 14A) having the three vertex coordinate values represented by the device coordinate system (DC). Based on the algorithm of a predetermined digital differential analyzer (DDA), the coordinate values of the outer peripheral line are calculated, and the calculated coordinate values (coordinate data with decimal points) and the display coordinates of a display device (not shown) ( This is a part for detecting the coordinates (the pixel coordinates: integer) of the end point of the inner display area surrounded by the outer peripheral line from the difference between the pixel and the pixel.

First, conventionally, when a triangle with an outer peripheral line is surface-painted and drawn, the triangle clipped by the clipping processing unit 10 and the outer peripheral line data control unit 11 of the above-mentioned triangle clip processing unit 1 is used as shown in FIG. In (a) and (b),
It is divided into triangle vertex data showing the data format and outer peripheral line vertex data.
0 is transferred to the outer peripheral line retraction processing unit 20a of the scan conversion unit 20 of the DDA processing unit 2 shown in FIG. Generate the span data required for painting.

The span data is, for example, as shown in FIG.
(DC) Y coordinate value (Yspan1 ~), X coordinate value of the start point of the span (Xs1 ~) and X coordinate value of the end point of the span (Xe1 ~)
~) And the coordinate values in the depth direction (Zs1 ~), etc., the generated span data list is sent to the drawing data conversion unit 3 and converted into span drawing data composed of dot data in the span data conversion unit 30. The drawing processing unit
Dispatched to 4.

Subsequently, in the outer peripheral line processing unit 22, the outer peripheral line vertex data obtained from the outer peripheral line data control unit 11 (see FIG. 14).
Perform the DDA processing of the outer peripheral line from the format reference in (b) and omit the detailed description of the meaning of each data}, send it to the drawing processing unit 4 via the outer peripheral line data conversion unit 32, and draw the triangle with the outer peripheral line. Is guaranteed.

FIG. 11 and FIG. 12 show the conventional surface painting method for a triangle with an outer peripheral line. FIG. 11 (a) shows a basic triangle to be drawn, and the ● mark indicates the given triangle. The theoretical device coordinates of the basic triangle are shown in Fig. 11 (b).
When drawing the triangle shown in FIG. 11 (a), an actual drawing area is shown when drawing up to the area inside the triangle (this is called the span). That is, FIG. 11 (b)
In, the thick line indicates the theoretical value of the triangle and the thin line indicates
It shows the triangle that is actually displayed, and the triangle ΔA ”
B "C" indicates a triangle obtained by rounding (rounding) the three vertices of the triangle ABC indicated by the theoretical value to the pixel (pixel) position actually displayed on the display. Therefore, the area portion (ie span) of the triangle
Are represented by pixels indicated by □ in FIG. 11 (b). FIG. 12 (c) shows a drawing example in which a triangle drawn up to the span shown in FIG. 11 (b) is drawn up to the outer peripheral line, and a black square indicates the drawn outer peripheral line. Represents a pixel. The pixel of the peripheral line at this time is a predetermined D
It is generated by DA processing.

The drawing of the triangle is performed as described above by the digital differential analyzer (which determines the end points of the triangular area (span) when the so-called hidden surface removal processing is performed based on the value of the Z buffer in the polygon drawing. Because of the difference between the DDA processing and the DDA processing of the outer peripheral line, when the same pixel is drawn in the order of the triangular area portion (span) and the outer peripheral line (vector), the difference in the calculated Z value is This is to prevent a pixel that should display the outer peripheral line from being displayed as a pixel in the triangular area portion (span).

Due to the difference in the DDA processing described above, the problem that a pixel that should originally display the outer peripheral line is displayed as a pixel in the triangular region (span) is shown in FIG.
A detailed description will be given with reference to No. 3.

In FIG. 13, it is assumed that the mark ● indicates the theoretical coordinate value of the triangle, and the mark □ indicates the coordinate value when the triangle is clipped in a predetermined window. The DDA processing for obtaining the end points of the triangular area (span) uses the theoretical value after the device coordinate value is subjected to the triangle clipping processing, while the DDA processing for obtaining the outer peripheral line (vector) uses the outer peripheral line. The device coordinate value rounded off is used to match the theoretical value after clipping to the pixel.

That is, the two vertices A and B (the outer peripheral lines are points C and D) of a certain triangle shown in FIG.
Regarding the value, considering the case of clipping with Zmin and Zmax, in the case of the area portion (span) of the triangle, the DDA processing is performed with the theoretical value, and therefore the points A ′ and B ′ on the original theoretical value are inherited. However, in the case of an outer peripheral line, after the outer peripheral line is clipped, DDA processing is performed using points that are rounded off to pixel positions, such as points C ′ and D ′, and thus deviate from the above theoretical value. A line segment (vector) will be drawn.

Due to the above difference in DDA processing, the drawing processing unit
In 4, when drawing the same pixel (pixel indicated by X and Y in device coordinates), after drawing the area part (span) holding the above theoretical Z value corrected to the actual pixel position , When an outer peripheral line (vector) that does not hold the theoretical Z value is drawn, the drawing result of the triangular area portion (span) is displayed on the screen at each pixel of the outer peripheral line. Is a problem.

[0015]

In the above-mentioned conventional triangle drawing method, the outer peripheral line is a solid line (continuous dot line, that is,
When it is not a pattern), since the outer peripheral line is drawn by the continuous pixels forming the outer peripheral line,
The drawing result of the triangular area portion (span) is not displayed on the screen at the pixels of the outer peripheral line, but when the outer peripheral line is a pattern, the outer peripheral line is not continuous. However, there is a problem that the drawing result of the triangular area portion (span) may be displayed on the screen at the outer peripheral line, that is, at portions where there is no pattern.

In view of the above-mentioned conventional drawbacks, the present invention draws a triangle with an outer peripheral line that is not a solid line, and the outer peripheral line retraction processing unit uses the inner area portion (span) surrounded by the outer peripheral line as a drawing data conversion unit. After sending, the hollow data having the same vertex coordinate value as the triangular area (span) is sent to the drawing data conversion unit as boundary line data, and then the vertex data of the outer peripheral line is sent. An object of the present invention is to provide a graphic display device capable of guaranteeing the drawing result of a triangle with an outer peripheral line of a peripheral line pattern.

[0017]

FIG. 1 is a block diagram showing the principle of the present invention. The above problems can be solved by the graphic display device configured as follows.

(1) At least a triangle clip processing unit 1 forming a triangle clipped by a window set on the display surface, an outer peripheral line retraction processing unit 20a, a hollow wire processing unit 21, and an outer peripheral line processing unit 22. A graphic display device having a DDA processing unit 2, a drawing data converting unit 3 for converting drawing data into dot data, and a drawing processing unit 4 for performing actual drawing, which is clipped by the triangle clip processing unit 1. When a triangle with an outer peripheral line is divided into a triangular area portion and an outer peripheral line and drawn, the outer peripheral line of the triangle is excluded from the span data calculated by the outer peripheral line retraction processing unit 20a in the DDA processing unit 2. Boundary line data for performing the same hollow line processing as the conventional hollow line is generated by using the outer peripheral line part after drawing the area as the boundary line,
Boundary line data control unit 21a to be transferred to the hollow line processing unit 21
And the boundary data generated by the hollow line processing unit 21 and the outer peripheral line processing based on the span data generated by the triangle clip processing unit 1 and the control of the boundary line data control unit 21a. The peripheral line data generated by the unit 22 is configured to be drawn and displayed by the drawing processing unit 4.

(2) The graphic display device according to the above item (1), wherein the hollow line data conversion unit in the drawing data conversion unit 3 is used.
A hatch reference control unit 311 is provided in the 31 to enable the DDA.
Based on the control of the boundary line data control unit 21a in the processing unit 2, the boundary line data portion generated by the hollow line processing unit 21 is
In advance, it is configured to draw and display a hatch pattern specified for each drawing address.

[0020]

1 is a block diagram showing the principle of the present invention, and FIG.
It is a figure explaining the boundary line drawing type of the triangle of this invention. In FIG. 1, except for the boundary line data control unit 21a and the hatch reference control unit 311 (the lower right of the control unit is indicated by a solid black triangle), the configuration is the same as that of the conventional graphic display device.

The boundary line data control unit 21a is a clipping processing unit 1 provided in the triangle clipping processing unit 1.
Based on 0 and the outer peripheral line visibility information (referred to as line flag) added to the triangular data (area part data) divided by the outer peripheral line data control unit 11 and each triangular vertex data (see FIG. 8) of the outer peripheral line data. As shown in FIG. 2, the boundary line segment of the triangle is divided into a plurality of minimum necessary drawing types in which the vertices do not overlap each other, and is generated and passed to the hollow line processing unit 21, which is an existing process. To do.

That is, in the graphic display device of the present invention, regarding the triangle with the outer peripheral line, the boundary line data control unit 21a
The vertex coordinate values of the triangle are managed, and the minimum necessary triangle vertex coordinate values as the boundary line of the triangle are sent to the drawing data conversion unit 3 as graphic data. The DDA process for generating the boundary line at this time is the same as the DDA process for the outer peripheral line. By this processing, in the drawing data conversion unit 3 and later, the boundary line data sent is regarded as triangular data having a hollow internal format, hollow line processing similar to the conventional one is executed, and the boundary line It is drawn with the same area color as the internal area (span) of the triangle. The same DD for this border
By drawing the pattern data of the outer peripheral line processed in A in the form of overwriting, part of the drawn boundary line is
Boundary area The outer peripheral line that remains the same color is drawn. As a result, the same effect as when drawing a solid outer peripheral line is obtained, and even when hidden surface processing is performed, the area of another triangular area part It is possible to prevent the color from being drawn.

Further, the hatch reference control unit 311 provided in the drawing data conversion unit 3 sends data based on bit 4 of an interior flag described later in the boundary line data sent from the hollow line processing unit 21. If the received boundary line data is a solid boundary line data, it is judged whether it is a hatch boundary line data. In the case of a hatch, the hatch pattern indicated by the internal style of the hollow line data is acquired and referred to For each pixel forming a, by comparing the bit with the hatch pattern, by drawing the outer peripheral line of the invisible portion of the outer peripheral line in the hatch pattern, a part of the drawn boundary line, It is drawn with a hatch pattern, and as a result, the same effect as when drawing the solid outer line is obtained, and even when the hidden surface processing is applied, it is possible to prevent the area color of the other triangular area part from being drawn. Can .

[0024]

Embodiments of the present invention will be described in detail below with reference to the drawings. The above-mentioned FIG. 1 is a block diagram of the principle of the present invention.
3A and 3B are diagrams for explaining a triangle boundary line drawing type of the present invention, FIG. 3 is a diagram for explaining a visible flag of a boundary line, and FIG. 3A shows a boundary line visible flag; (b) is
FIG. 3C is a diagram for explaining the relationship between the boundary visible flag and the boundary vertices. FIG. 3C shows a state in which a triangle is clipped by a clip frame, and FIG. 4 shows boundary drawing of the present invention. It is a figure which shows the relationship of a boundary line visible flag, and FIGS.
FIG. 8 is a processing flow diagram of a boundary line data control unit and a hollow line processing unit of the present invention, FIG. 7 is a processing flow diagram of a hatch reference control unit of the present invention, and FIG. 8 is a triangle drawing data list of the present invention. The structural example figure is shown.

In the graphic display device of the present invention, at least
Triangle clip processing unit 1 that forms a triangle clipped by a window set on the display surface, scan conversion unit 20 that draws the internal area (span) of the triangle, outer peripheral line retraction processing unit 20a, and hollow line processing unit 21
A DDA processing unit 2 including an outer peripheral line processing unit 22, a drawing data conversion unit 3 for converting drawing data into dot data, and a drawing processing unit 4 for performing actual drawing. After drawing the area excluding the outer peripheral line from the triangle with the span data calculated by the outer peripheral line retraction processing unit 20a in 2, the boundary line data control unit
21a and the hollow line processing unit 21 that performs hollow processing draws the boundary line by the same processing as the conventional hollow wire, and then,
A means for drawing the outer peripheral line pattern in the outer peripheral line processing unit 22 in the form of overwriting, or a hatch reference control unit 311 in the hollow line data converting unit 31 of the drawing data converting unit 3 of the same graphic display device. Then, the boundary data portion generated by the boundary data control unit 21a and the hollow line processing unit 21 in the DDA processing unit 2 is drawn in advance in accordance with the hatch pattern designated for each drawing address. The means for displaying is the means necessary for carrying out the present invention. The same reference numerals indicate the same objects throughout the drawings.

2 to 7 while referring to the conventional graphic display device described in FIG. 10 and FIG.
The configuration of the graphic display device of the present invention and the drawing operation of the triangle with the outer peripheral line will be described.

First, the graphic display device of the present invention has the configuration shown in FIG. 1, and the basic drawing method is the same as the conventional one described in FIG. As described above, the conventional method of drawing a triangle with an outer peripheral line guarantees only when the outer peripheral line is a solid line. That is, when the outer peripheral line is pattern data, when the hidden surface processing is performed, a hidden triangular area portion (span) is displayed on the screen at each of the outer peripheral lines formed of the pattern data. There was a problem that there is. Therefore, in the graphic display device of the present invention, the boundary line data control unit 21a for controlling the hollow line processing unit 21 of the DDA processing unit 2 is provided, and the area portion (span) where the outer peripheral line is removed from the triangle with the outer peripheral line is drawn. After that, in the boundary line data control unit 21a, the minimum necessary boundary line data having the same vertex coordinates as the drawing target triangle (see FIG. 8 (d)).
Boundary line data list shown in [1]
The boundary line is generated in the DA process, the boundary line is drawn in the same area as the outer circumference line, and the drawn boundary line is overwritten with the pattern of the outer circumference line.

The boundary line drawing process will be described in detail with reference to FIGS. 3A and 3B are views for explaining the visible flag of the boundary line, FIG. 3A shows a configuration diagram of the boundary line flag, FIG. 3B shows the relationship between the vertex and the boundary line flag, and FIG. c) shows the situation where the triangle is clipped by the clip frame.

As shown in FIG. 3A, the boundary line flag is
It is set to the 0 bit position in the 32-bit border line flag data. When the 0 bit is "1", the border line is visible (with drawing), and when it is "0", the border line is set. Indicates invisible (no drawing). This border line flag is shown in FIG.
As shown in (b), the boundary line flag of the boundary line between the vertex n and the vertex n + 1 (en: means the edge n) is added to the coordinate data of the vertex n, and the coordinate data of the vertex n + 1 is also added to the coordinate data. A boundary line flag of edge en + 1 is added, and a peripheral line flag of edge en + 2 is added to vertex n + 2.

FIGS. 5B and 6 are process flow charts of the boundary line data control unit of the present invention. In this processing flow, the clipping processing section 10 of the triangle clipping processing section 1 described above creates a triangle having vertices P1, P2 and P3 shown in FIG. 5 (a) and clips the outer peripheral line portion of each edge. It is assumed that the boundary line is a triangle, and the boundary line flags of the respective boundary line edges have the same relations as in FIG.
It is assumed that the boundary flag of each edge is added to the coordinate data, and either "0" or "1" is arbitrarily set as the boundary flag of each edge.

When the process of FIG. 5B is started, the process of the boundary line data control unit 21a of the present invention is executed, and a line flag () provided in a specific area of a memory (not shown) inside is executed. Initialize a variable named LineFlag (specified area of memory) to "0". {Refer to processing step 100 in FIG. 5B} Next, in processing step 101, the following processing is executed. That is, first, the content of the boundary line flag of the edge (edge1) is set to the line flag (LineFlag). At this time, as shown in FIG. 3A, the content (“0”, which indicates the flag set at the 0-bit position in 32 bits,
Alternatively, "1") is set to the 0th bit position of the line flag.

Next, the boundary line flag of the edge 2 is shifted to the left by 1 bit, and the bit of the boundary line flag is shifted to the left (1 bit to the left. Yes) is set to the corresponding first bit position of the line flag (LineFlag) composed of 32 bits. Furthermore, the boundary line flag of edge 3 (edge3) is shifted to the left by 2 bits, and the bit of the boundary line flag (since it is shifted to the left by 2 bits, it is at the second bit position within 32 bits), It is set to the second bit position corresponding to the line flag (LingFlag).

FIG. 4 shows the boundary line drawing and the line flag (L
ineFlag) and the visible flag. The processing contents of the processing step 101 will be described with reference to FIG.
In FIG. 4 (a), is the above edge 1 to edge 3
Indicates the state after the corresponding left shift has been performed, and indicates the line flag (LineFlag). As a result of the shift and setting processing described above, the contents of the boundary flag bits set at the 0th bit positions of the line flag (Lin
eFlag) is set in three bit positions (bits 0, 1, 2).

Returning to the processing of FIG. 5, it is next determined whether the content of the line flag (LineFlag) obtained as described above is "0" or "1". {Refer to processing step 102 of FIG. 5 (b)} If all the contents of the line flag (LineFlag) are “0” (all bits are “0”) in this judgment, there is no boundary line to draw, so the boundary line The process of this boundary line data control process 21a is terminated without drawing. The line flag (L
If the content of ineFlag) is not "0", the above line flag
The jump destination is set by (LineFlag) {see processing step 103 in FIG. 5B}, and the set jump destination (M1 to M
7): M1 to M7 will be described later). {Refer to processing step 104 in FIG. 5B} This jump destination is the processing of the hollow wire processing unit 21 shown in FIG.

Now, the operation of the line flag (LineFlag) will be described with reference to FIG. 4. As shown in FIG. 4A, the lower 3 bits of the line flag (LineFlag) have an edge at the lowest 0 bit position. The boundary flag of 1 is set, the boundary flag of edge 2 is set at the 1-bit position, and the boundary flag of edge 3 is set at the 2-bit position. The range represented by the lower 3 bits of this line flag is "000"
It is "111", and it has 8 values from 0 to 7 in decimal.

The table shown in FIG. 4B shows the above line flag.
The eight values of (LineFlag) represent that each represents a drawing pattern of a boundary drawing line segment, and a pattern example of the boundary drawing line segment corresponding to each of the above values is shown in FIG. 2 described above. It is a thing.

That is, in FIG. 4B, the number (1) is the case where the line flag (LineFlag) is "0", no drawing is performed as described above, and the jump destination is M0 {FIG. 5 ( In the processing step 102 of b), the line flag (LineFlag) is "0".
If it is determined that}, the boundary line drawing line segment is
It is not transferred as shown in (1). The number (2) indicates that the line flag (LineFlag) is "1", and the boundary line drawing line segment indicates to draw between the vertices P1 and P2 of the triangle shown in FIG. 3 (b). However, the boundary line edge to be used is edge 1 (edge1), and the jump destination is M1. In this case, the drawing shown in FIG. 2B is performed at the jump destination.

Similarly, the numbers (3) to (8) correspond to the values of "2" to "7" of the line flag (LineFlag) shown in FIG.
Each vertex section shown in the boundary line drawing line segment in (b) indicates to draw using the corresponding boundary line edge, and each jump destination is M2 to M2 corresponding to the numerical value of the line flag (LineFlag). It is M7.

FIG. 6 shows the boundary line data control unit shown in FIG.
The processing flow of the hollow wire processing unit 21 jumped from 21a is shown, and the corresponding hollow processing is executed according to any of M1 to M7 set as the jump destination, and after the execution, the hollow processing shown in FIG. ) To end. Incidentally, M1 to M7 correspond to the cases of the numbers (2) to (7) in FIG. 4 (b).

For example, when the jump destination is M1, the data of the first vertex {P1 of the triangle of FIG. 5 (a)} is stored in the graphic data storage unit (not shown) in the hollow line processing unit 21, Next, the data of the second vertex {P2 of the triangle in FIG. 5 (a)} is stored. This allows P1-P2 as shown in Fig. 2 (2).
A boundary line between them is drawn.

The case of drawing the two boundary lines created by the clip shown in FIG. 3C corresponds to the case of drawing between the vertices P2-P3-P1 of the triangle of FIG. 5A. . At this time, the 3 bits of the line flag (LineFlag) are set to "110" and the decimal number is "6", so that the process jumps to M6. In this case, according to the processing flow of FIG. 6, the data of the second vertex (P2) is stored in the graphic data storage unit, the data of the third vertex (P3) is stored, and the data of the first vertex (P1) is stored. When the three vertex data are sequentially stored and stored, these data are drawn in the frame memory (not shown) in the hollow line data converter 31 of the drawing data converter 1 in FIG.

In this case, the vertex data transferred to the drawing processing unit 4 of FIG. 1 is three pieces of data in which two boundary line segments are connected, and two vertex data of start point-end point are provided for each line segment. It is not necessary to transfer, the memory capacity can be reduced, and the transfer time can be shortened.

The processing flow in the boundary line data control section 21a is the same as the Japanese Patent Application No. 05-244246 "peripheral line drawing data control method" filed by the applicant of the present application on September 30, 1952. It is disclosed as a drawing method of the outer peripheral line of the triangle clipped by the above method. In the present invention, by applying this outer peripheral line drawing method to the boundary line drawing of the present invention, the boundary line drawing is performed. Is performed efficiently and is not the main object of the present invention.

One of the main points of the present invention is, as described above, when drawing a triangle clipped by a predetermined window, after drawing the internal area (span) of the triangle, the same as the triangle. By redrawing the original outer peripheral line pattern generated by the same DDA processing by overwriting the boundary line drawn by performing the conventional hollow processing with the outer peripheral line portion of the triangle having the vertices as the boundary line, The same drawing effect as that of the solid line is obtained even for the peripheral line of the pattern which is not the solid line.

Next, the drawing means by the hatch, which is another feature of the present invention, is shown in the principle configuration diagram of FIG. 1, the processing flow diagram of the hatch reference section of FIG. 7, and the display example of the hatch pattern of FIG. It will be described with reference to FIG.

In the hatch reference control unit 311 in the drawing data conversion unit 3 shown in FIG. 1, there is an interior flag (not shown) at the 4th bit position of the line flag (LingFlag) and the boundary line data. Is a hatch, the fourth bit is set (ON), and in the case of a solid boundary line, the fourth bit is not set (OFF).

When the boundary line data is sent from the hollow line processing unit 21 started by the boundary line data control unit 21a and the hatch reference control unit 311 is started up, first, the line flag (LingFlag) is set. The 4th bit position of is checked to determine whether the interior flag (InterriorFlag) is on. If the hatch drawing is instructed to the boundary line, the corresponding hatch pattern is obtained from the upper device (not shown) on the RAM 33. {Fig. 7
Processing steps 200 and 201}, the hatch pattern is, for example, as shown in FIG. 9, a pattern composed of 32 bits × 32 bits pixels, and image data displayed on the display of a display device (not shown). The bit map memory (corresponding to the frame memory described above) that stores a number has a capacity that is an integral multiple of the 32 bits, and when a figure is displayed in a hatch, which pixel on the frame memory is the 32 bits x 32 bits. It is determined which pixel of the hatch pattern made up of bit pixels corresponds. That is, as shown in FIG. 9, the frame memory is divided and displayed in the pattern composed of the above 32 bits × 32 bits pixels.

Therefore, when a certain figure is displayed by a certain window, the correspondence between the framed area in the window and the 32 bit × 32 bit area allows the window to be displayed, for example, in a triangle. The hatch pattern is various pieces (partial) patterns of the above-described hatch pattern composed of 32 bits × 32 bits. Depending on the bit position on the frame memory of the drawn triangle, the hatch pattern displayed in advance is , Will be set. (See FIG. 9.) Therefore, when the boundary line of the triangle with the outer peripheral line according to the present invention is displayed in the area color of the internal area (span), the address calculated by the DDA process using the device coordinate value rounded to the theoretical value ( R corresponding to the above pixel)
When the hatch pattern on the AM is determined and coincides (the hatch pattern exists), the hatch pattern is output to the drawing processing unit 4 in FIG. 1 as the boundary line drawing data. {Refer to processing steps 201 to 203 in FIG. 7} If there is no corresponding hatch pattern in the determination processing in the above processing step 202, the processing moves to processing step 204, and the next pixel on the boundary line of the triangle to be drawn is detected. Coordinate value,
The color is calculated and the hatch pattern of the pixel is
It is read from the hatch pattern on the AM, and in the processing step 202, it is judged whether or not the hatch pattern exists.

In this way, in the hatch pattern drawing means according to the present invention, based on the vertex coordinates of the triangle, the boundary line address (the above-mentioned pixel described above) calculated by the DDA process using the device coordinate value obtained by rounding off the above theoretical value. )
If the area color is drawn in correspondence with or the hatch pattern exists at the address, the corresponding hatch pattern is drawn by the drawing processing unit 4 as the drawing data of the pixel on the boundary line. Become.

Therefore, since the hatch pattern corresponding to the address is drawn based on the address generated by the same DDA process as that of the outer peripheral line, the same drawing effect as the solid line can be obtained.

As described above, the graphic display device of the present invention includes at least a triangle clip processing section for forming a triangle clipped by a window set on the display surface.
A graphic display device comprising a DDA processing unit, a drawing data conversion unit for converting drawing data into dot data, and a drawing processing unit for performing actual drawing, wherein a boundary line data control unit is provided in the DDA processing unit, and an outer peripheral line is provided. When the attached triangle is divided into an inner area (span) of the triangle and an outer peripheral line and drawn, the above DD
After drawing a region (span) from the triangle in which the outer peripheral line is removed with the span data calculated by the outer peripheral line retraction processing unit in the processing unit, the removed outer peripheral line portion is instructed by the boundary line data control unit. Is used as a boundary line and is drawn by the hollow line processing unit in the same process as the conventional hollow line, and subsequently, the outer peripheral line pattern is drawn by overwriting the boundary line drawn as the hollow line. When the boundary line is drawn in a hatch pattern, the boundary line portion is drawn in a corresponding hatch pattern.

[0052]

As described above in detail, according to the graphic display device of the present invention, when a triangle with an outer peripheral line is drawn, (1) even when the hidden surface processing is enabled, a line other than the solid line is displayed. In all of the outer peripheral line patterns, the hidden triangular area portion (span) can be drawn without being displayed on the outer peripheral line pattern.

(2) Further, even if the triangular area portion is like a hatch, if the boundary line of the triangle is made to correspond to the bit of the hatch pattern, the portion of the outer peripheral line having no pattern is accurately drawn in the hatch pattern. can do.

[Brief description of drawings]

FIG. 1 is a block diagram of the principle of the present invention.

FIG. 2 is a diagram for explaining a triangle boundary line drawing type of the present invention.

FIG. 3 is a diagram illustrating a visible flag of a boundary line.

FIG. 4 is a diagram showing a relationship between a boundary line drawing and a boundary line visible flag according to the present invention.

FIG. 5 is a processing flow chart of the boundary line data control unit of the present invention (No. 1)

FIG. 6 is a processing flow chart of the boundary line data control unit of the present invention (No. 2)

FIG. 7 is a processing flow chart of a hatch reference control unit of the present invention.

FIG. 8 is a structural example diagram of a triangle drawing data list of the present invention.

FIG. 9 is a diagram showing a display example of a hatch pattern.

FIG. 10 is a diagram (part 1) illustrating a conventional method and apparatus for drawing a triangle with a peripheral line.

FIG. 11 is a diagram (part 2) illustrating a conventional method and apparatus for drawing a triangle with a peripheral line.

FIG. 12 is a diagram (part 3) for explaining a conventional method and apparatus for drawing a triangle with a peripheral line.

FIG. 13 is a diagram (part 4) illustrating a conventional method and apparatus for drawing a triangle with a peripheral line.

FIG. 14 is a diagram for explaining a conventional method and apparatus for drawing a triangle with a peripheral line (Part 5).

[Explanation of symbols]

1 Triangle clip processing unit 10 Clipping processing unit 11 Perimeter line data control unit 2 DDA processing unit 20 Scan conversion unit 20a Perimeter line retraction processing unit 21 Hollow line processing unit 21a Boundary line data control unit 22 Perimeter line processing unit 3 Drawing data conversion unit 30 Span data conversion unit 31 Hollow line data conversion unit 32 Perimeter line data conversion unit 310 Hollow line drawing data unit 311 Hatch reference control unit 33 RAM

Claims (2)

[Claims] 1. A triangle clip processing unit for forming a triangle clipped by a window set on a display surface, a DDA processing unit including a peripheral line retraction processing unit, a hollow line processing unit and a peripheral line processing unit, A graphic display device comprising a drawing data conversion unit for converting drawing data into dot data, and a drawing processing unit for performing actual drawing, wherein a triangle with an outer peripheral line clipped by the triangle clipping processing unit is a triangular area portion. And the outer peripheral line are drawn separately, the outer peripheral line portion after drawing the area excluding the outer peripheral line of the triangle in the span data calculated by the outer peripheral line retraction processing unit in the DDA processing unit is the boundary. As a line, a boundary line data control unit that generates boundary line data for performing the same hollow line processing as a conventional hollow line and transfers it to the hollow line processing unit is provided. Then, under the control of the span data generated by the triangle clip processing unit and the boundary line data control unit, the boundary line data generated by the hollow line processing unit and the outer peripheral line processing unit are generated. A graphic display device, wherein the peripheral line data is drawn and displayed by the drawing processing unit. 2. The graphic display device according to claim 1, wherein:
A hatch reference control unit is provided in the hollow line data conversion unit in the drawing data conversion unit, and based on the control of the boundary line data control unit in the DDA processing unit, the boundary line data portion generated in the hollow line processing unit. Is drawn and displayed in a hatch pattern specified in advance for each drawing address.