JP2783090B2 - Drawing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a computer assisted design (CA)
Among the functions of the graphic drawing apparatus used in D) and the like, the present invention particularly relates to a graphic drawing method for drawing a line segment used as a wire frame of a graphic.

[0002]

2. Description of the Related Art To draw a graphic on a display device such as a display, first, a clip frame, which is a graphic drawing area on the display device, and the type and width of a line segment forming the outline of the graphic to be drawn. Is set. Furthermore, the specification of a drawing projection method for selecting perspective projection for giving a perspective to a figure to be drawn and parallel projection for giving no perspective, presence / absence of depth skew processing for giving light and shade to a line segment, and hidden line hidden surface processing Set the drawing processing information such as the presence or absence of.

The above three setting conditions are input as attribute data of a graphic, and further, as graphic data, coordinates of a vertex of a graphic which is an end point of a line forming a contour of the graphic to be drawn are input. FIG. 10 is a diagram illustrating a clip frame on the display device, and FIG. 11 is a diagram illustrating a relationship between vertices of a drawing figure and line segments.

FIG. 12 is a flowchart showing the flow of a conventional graphic drawing process. In FIG. 12, coordinate conversion into a clip frame is performed on the vertex coordinates input as graphic data, and whether the vertex whose position is specified by the coordinate conversion is inside or outside the clip frame Is determined inside / outside the clip frame. When it is determined that the vertex is within the clip frame, a homogeneous normal coordinate transformation that is a coordinate transformation to normal coordinates corresponding to the position coordinates on the display device is performed, and when the vertex is outside the clip frame. If it is determined, the same normal coordinate transformation is performed after clip processing, which is processing for vertices outside the graphic drawing area, is performed.

Here, the clip processing will be briefly described. FIG. 13 is a diagram illustrating a positional relationship between a clip frame and a vertex when performing clip processing. In FIG. 13, when the n-th vertex input as graphic data is inside the clip frame and the (n + 1) -th vertex is outside the clip frame (a), a line connecting the n-th vertex and the (n + 1) -th vertex The clip processing determines the position coordinates of the point A where the minute and the clip frame intersect.

Similarly, when both the n-th vertex and the (n + 1) -th vertex are outside the clip frame (b), the position coordinates of the intersections B ₁ and B ₂ are determined by the clipping process. If it is outside the clip frame and the (n + 1) th vertex is inside the clip frame (c), the position coordinates of the intersection C are determined by the clip processing. When the homogeneous normal coordinate transformation is performed on each vertex, next, in order to draw a line segment connecting the n-th vertex and the (n + 1) -th vertex on the display device, the line segment is preset in the graphic drawing device. Refer to the attribute definition table
If the attribute of the line segment on the display device is set and depth skew processing and hidden line hidden surface erasing processing are specified in the input attribute data, the processing is performed, and then the line The minute attribute is set.

As described above, when attribute data and graphic data of a graphic to be drawn are input, coordinate conversion processing, determination of inside and outside of a clip frame, clip processing as necessary, and A conversion process is performed, and a line connecting the vertices is subjected to attribute setting, and if necessary, a descue process and a hidden line hidden surface erasing process, and a graphic is drawn on a display device.

[0008]

By the way, when a figure is drawn by the perspective projection method, since the transformation values of the respective vertices in the homogeneous ordinary coordinate transformation processing are different for each vertex, the normal coordinates for each vertex are used. Needs to be converted to
When a figure is drawn by the parallel projection method, since the transformation value of each vertex in the homogeneous normal coordinate transformation process is constant for all vertices, if the homogeneous regular coordinate transformation is performed on the first vertex, It is not necessary to perform the conversion process to the normal coordinates after the vertex of.

However, in the conventional drawing method, even in the case of the parallel projection method, the unnecessary normal coordinate conversion processing is performed for each vertex after the second vertex, so that the amount of processing becomes enormous, The performance of drawing is degraded. In addition, referring to the attribute definition table for each vertex subjected to the same transformation, the process of setting the attribute of the line segment on the display device is performed, and the depth skew process and the hidden line hidden surface process are specified. If there is a conventional drawing method that also performs the processing,
The processing amount is too large, and the drawing process becomes slow.

Therefore, the present invention provides a method of reducing the processing for vertices that are continuously present in a clip frame and drawing the line at a high speed when drawing a figure by the parallel projection method. Aim.

[0011]

In the present invention, the means for solving the above-mentioned problems is, as shown in FIG. 1, a drawing format of a figure displayed on a display device. Designation information of the figure drawing area indicating the position of
Line segment information forming a contour of a figure, specification information of a parallel projection drawing method for omitting homogeneous normal coordinate conversion which is a coordinate conversion from the figure drawing area to normal coordinates, and specification information for omitting attribute setting Is a flag 1 in which is set as data
Provided in the drawing device, coordinate conversion to the figure drawing area,
And determining whether the figure is inside or outside the figure drawing area, and further performing the same normal coordinate transformation, and setting a figure attribute based on attribute data indicating the figure drawing format. If it is determined that the first vertex is in the graphic drawing area and the second vertex of the graphic is determined to be in the graphic drawing area, the flag is referred to, and If the attribute data matches the data of the flag, the process proceeds to pass 2 in which the same ordinary coordinate conversion and the setting of the attribute of the figure for the second vertex are omitted, and the drawing processing is performed. If it is determined that the third vertex is within the graphic drawing area, the drawing processing is performed in pass 2.

[0012]

According to the present invention, graphic data is input,
If the first vertex and the second vertex of the coordinate-transformed graphic are consecutively within the clip frame that is the graphic drawing area, the flag is referred to, and if the attribute data matches the data of the flag, Since the parallel projection drawing is set in advance, the drawing process is performed on the second vertex in the path that omits the setting of the ordinary normal coordinate conversion and the attribute of the figure. Can be shortened.

Then, the inside and outside of the clip frame is determined for the coordinate-transformed third vertex. If the third vertex is within the clip frame, the drawing process is performed in the pass, so that the amount of processing is reduced. Thus, the drawing processing ability is improved.
Further, once the process proceeds to the path of the present invention, as long as the read vertex continues in the clip frame, the vertex is processed in the pass, and when the read vertex goes out of the clip frame, the conventional graphic processing is performed. Back to the generic path
A clip process which is a process outside the graphic drawing area is performed.

[0014] Once a transition from the high-speed path to the general-purpose path,
If the subsequently read vertices are continuous in the clip frame, the process can proceed to the path of the present invention.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram illustrating a configuration example of an apparatus that performs a graphic drawing process. In FIG. 2, 11 is F
The IFO type memory stores graphic element data and attribute data of the graphic.

Reference numeral 12 denotes a geometry unit which reads out data stored in the FIFO memory 11 by a first-in first-out method and performs coordinate conversion processing, color calculation processing, clip processing, and the like. Reference numeral 13 denotes a rendering unit which determines the display content of a figure to be drawn on the display device by setting a drawing attribute based on the processing result of the geometry unit 12 and the input attribute data.

Reference numerals 14, 15, and 16 denote frame memories. The display contents of the graphic determined by the rendering unit 13 are written in one frame memory, and the display contents for one screen displayed on the display device are stored. However, FIG. 2 shows three frame memories as an example. 17
Is a Z-buffer which specifies which graphic element is to be displayed when a plurality of graphic elements are to be displayed at the same location on the display device.

Reference numeral 14 denotes a local storage which has an attribute definition table and the like and is also used as a work area. FIG.
FIG. 3 is a block diagram illustrating a configuration example of a geometry unit 12 and a rendering unit 13 in FIG. 2. In FIG.
It is assumed that the geometry unit 12 and the rendering unit 13 are configured by firmware.

The geometry section 12 has a data reading section 19 for reading data stored in the FIFO type memory 11 in a first-in first-out manner, a coordinate conversion section 20 for determining the position of a display graphic, and a color for processing the color of the graphic. Calculation unit 21
And a clip section 22 for performing clip processing. The rendering unit 13 includes a vertex processing unit 23 that interfaces with the clip unit 22 and a vector drawing unit 24 that performs line segment drawing processing based on the direction and size from the reference point.

The result of the drawing process performed by the vector drawing unit 24 is written to the frame memory. FIG.
FIG. 8 to FIG. 8 are flowcharts showing a drawing process in one embodiment of the present invention. In FIG. 4, first, the first vertex constituting the figure is read from the figure data stored in the FIFO type memory 11 (step 1), the coordinate conversion processing of the first vertex (step 2), and the color A calculation process (step 3) is performed, and then the inside / outside of the clip frame is determined for the first vertex (step 4).

If the first vertex is within the clip frame,
In FIG. 5, the first vertex, which is the starting point, is read as the end point (step 5), the second vertex is read as the starting point (step 6), the coordinate conversion processing of the second vertex (step 7), and the color A calculation process (step 8) is performed, and then the inside / outside of the clip frame is determined for the second vertex (step 9).

Further, when the second vertex is within the clip frame, the same normal coordinate transformation is performed on the first vertex as the end point (step 10), and the result is output to the rendering unit (step 10). Step 11) Then, a high-speed flag check is performed to determine whether the attribute data of the figure matches the flag (step 12). If the attribute data does not match the data set in the flag, the process proceeds to a general-purpose pass, which is a conventional drawing processing pass.

When the process proceeds to the general-purpose path, it is determined whether or not the reading of the vertices has been completed (step 13). If so, the same normal coordinate transformation is performed on the vertex as the starting point (step 14), and output to the rendering unit (step 15).

If the first vertex is outside the clip frame, the first vertex, which is the starting point, is read as the end point in FIG. 6 (step 16), and the second vertex is read as the starting point (step 17). , The coordinate conversion processing of the second vertex (step 18), and the color calculation processing (step 1)
9), and then the inside / outside of the clip frame is determined for the second vertex (step 20).

When the second vertex is within the clip frame, the clip processing is performed in which the first vertex as the end point is outside the clip frame and the second vertex as the start point is within the clip frame. (Step 21). Then, the same normal coordinate transformation is performed on the first vertex as the end point (step 22), and the result is output to the rendering unit (step 23), and it is confirmed whether the reading of the vertex is completed (step 24).

If the reading of the vertices has not been completed,
Replacing the second vertex, which is the start point, with the end point;
When the reading of the vertices is completed, the same normal coordinate transformation is performed on the second vertex as the starting point (step 25), and the result is output to the rendering unit (step 2).
6). In addition, in the clip vertex inside / outside determination steps 9 and 20 of the second vertex, when the second vertex is outside the clip frame, the first vertex which is the end point is outside the clip frame and the start point in FIG. A clip process in which the second vertex is outside the clip frame, or a clip process in which the first vertex as the end point is within the clip frame and the second vertex as the start point is outside the clip frame is performed (step 27). .

Thereafter, the same normal coordinate transformation is performed on the first vertex as the end point (step 28), and the result is output to the rendering unit (step 29), and it is confirmed whether the reading of the vertex is completed (step 28). 30). If the reading of the vertices has not been completed, the second vertex, which is the starting point, is read as the end point, and the process returns to step 16. If the reading of the vertices is completed, the second vertex, which is the starting point, is read. To perform the same normal coordinate transformation (step 31) and output it to the rendering unit (step 32).

In the rendering section, similarly to the conventional processing, the drawing attribute of the graphic on the display device is set with reference to an attribute definition table preset in the graphic drawing device. What has been described above is a drawing process similar to the conventional general-purpose path. In the following, in step 12, a flag check is performed, and the present invention shifts to a case where attribute data and data set in the flag match. The processing in the pass will be described.

When the process proceeds to the path of the present invention, it is confirmed in FIG. 8 whether the reading of the vertices is completed (step 3).
3) When the processing is completed, the second normal vertex, which is the starting point, is output to the rendering unit without performing the normal normal coordinate transformation (step 34). Moreover, the rendering unit does not perform the setting of the drawing attribute by referring to the attribute definition table, the depth skew process, and the hidden line hidden surface erasing process, and the display content of the data set in the flag is read into the frame memory. After the data is read to the display device, it is output to the display device.

On the other hand, if the reading of the vertices is not completed, the second vertex, which is the starting point, is read as the ending point (step 35), and the third vertex is read as the starting point (step 36). 3 (vertical coordinate)
7), and a color calculation process (step 38) is performed, and then the inside / outside of the clip frame is determined for the third vertex (step 39).

If the third vertex is within the clipping frame, it is output to the rendering unit without performing the same normal coordinate transformation on the second vertex as the end point (step 40), and the reading of the vertex is completed again. The process returns to step 33 for checking whether Moreover, the rendering unit does not perform the setting of the drawing attribute by referring to the attribute definition table, the depth skew process, and the hidden line hidden surface erasing process, and the display content of the data set in the flag is read into the frame memory. After the data is read to the display device, it is output to the display device.

If the third vertex is outside the clip frame, the process proceeds to step 27 in which the second vertex as the end point is within the clip frame and the third vertex as the start point is outside the clip frame. The process proceeds, and returns to the general-purpose path which is the conventional drawing process. In addition, continue reading the vertices further,
If there are consecutive vertices in the clip frame, it is possible to shift to the path of the present invention again.

FIG. 9 is a diagram for explaining a data format of a flag according to an embodiment of the present invention. The plug data includes information indicating the type of line, information indicating the width of the line, information indicating the number of clip frames, information indicating the projection method, and HLHSR.
Information indicating the mode and information indicating the HLHSR identifier are included. The 0th bit of the 32-bit data is 0 when the line type is a solid line, 1 when the line type is not a solid line, and 1 in the first bit.
0 when the line width is greater than 1, 1
Further, the second bit is 0 when the number of clip frames is one, and 1 when the number of clip frames is more than one.
Is set.

Then, the third bit is 0 for parallel projection, 1 for perspective projection, and the fourth bit is 0 when the Z buffer is not used, and 1 when the Z buffer is used. However, in the fifth bit, 1 is set when hidden line erasure is not performed, and 0 is set when hidden line erasure is performed. Bits 6 to 31 are empty areas, and thus 0 is set.

[0035]

As described above, according to the present invention,
Unnecessary processing can be simplified, processing for drawing a figure with frequently used attribute data can be performed efficiently, and there is an effect that figure drawing can be speeded up. A figure that is frequently drawn by CAD or the like mainly has many vertices specified in a clip frame, and may be drawn by a parallel projection method using a line segment whose line type is a solid line and whose line width is 1. Since there are many, there is an effect that figure drawing can be performed efficiently.

[Brief description of the drawings]

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

FIG. 2 is a block diagram illustrating a configuration example of an apparatus that performs a graphic drawing process according to an embodiment of the present invention.

FIG. 3 is a block diagram illustrating a configuration example of a geometry unit and a rendering unit according to an embodiment of the present invention.

FIG. 4 is a first flowchart illustrating a drawing process according to the embodiment of the present invention;

FIG. 5 is a second flowchart illustrating a drawing process according to the embodiment of the present invention;

FIG. 6 is a third flowchart illustrating a drawing process according to the embodiment of the present invention;

FIG. 7 is a flowchart 4 showing a drawing process in the embodiment of the present invention.

FIG. 8 is a flowchart 5 showing a drawing process in the embodiment of the present invention.

FIG. 9 is a diagram illustrating format data of a flag in one embodiment of the present invention.

FIG. 10 is a diagram illustrating a clip frame on the display device.

FIG. 11 is a diagram illustrating a relationship between a vertex of a drawing figure and a line segment;

FIG. 12 is a flowchart showing a flow of a conventional drawing process.

FIG. 13 is a diagram illustrating a positional relationship between a clip frame and a vertex in clip processing.

[Explanation of symbols]

 1 ... Flag 2 ... Pass

Claims (1)

(57) [Claims] 1. A method of drawing a graphic on a display device based on graphic data indicating a position of a vertex of the graphic and attribute data indicating a drawing format of the graphic, the method comprising: Performing coordinate conversion to a graphic drawing area indicating the position of the graphic to be drawn on the device, determining whether the figure is inside or outside the graphic drawing area, and further determining the vertex determined to be within the graphic drawing area and the graphic If it is outside the drawing area, the same normal coordinate conversion as the coordinate conversion from the figure drawing area to the normal coordinates for the vertex subjected to the processing outside the figure drawing area, and setting of the attribute of the figure by the attribute data The method of drawing a figure by a drawing process for performing a drawing process includes the following: a drawing format of a figure to be displayed on a display device; A flag (1) in which designation information of parallel projection drawing method for omitting coordinate conversion and designation information for omitting attribute setting are set as data in the drawing device, When it is determined that the first vertex is in the graphic drawing area and that the second vertex of the graphic is in the graphic drawing area,
When the flag is referred to, and the attribute data of the figure matches the data set in the flag, the path (2) omitting the same normal coordinate conversion and setting of the attribute for the second vertex is omitted. ), The drawing process is performed, and if it is determined that the third vertex of the figure is within the figure drawing area, the drawing process is performed in the path (2). How to draw figures.