JPH0281179A - Picking circuit - Google Patents

Abstract

PURPOSE:To shorten the processing time by providing a position deciding circuit for executing a pick decision by a position relation of areas in which a start point, a middle point and an end point of divided segments are positioned, respectively. CONSTITUTION:When coordinates of a start point and an end point of a segment to be picked are informed to a picking circuit 18, codes of the start point and the end point are calculated by a code calculating circuit 26. By using the code obtained by the circuit 26, where a designated segment is picked or not is decided by a code deciding circuit 24. When whether it is picked or not cannot be determined by a decision of the circuit 24, a position deciding circuit 25 executes a middle point division with regard to the segment which cannot be decided, and executes a pick decision by a position relation of areas in which the start point, the middle point and the end point of divided segments are positioned, respectively. In such a way, that which is picked clearly and that which is not picked can be decided on the way of a study, and the processing time is shortened.

Description

[Detailed Description of the Invention] [Summary] For example, in the operation process of creating a figure using a figure processing system such as CAD, a figure on the screen is interactively selected,
Regarding the picking circuit when editing shapes such as moving, enlarging, and reducing, the midpoint division method has been improved, and it is now possible to correspond to intermediate midpoints and their midpoints without having to repeat midpoint division until an intersection is obtained. The purpose is to speed up the picking process by determining whether or not the starting point and end point intersect with the pick area based on the positional relationship between the starting point and the end point, and to make the selection of shapes in CAD and other graphic processing more efficient. It is determined whether the line segment passes within the range according to the positional relationship of the regions in which each of the lines are located, and for line segments that cannot be determined based on this, midpoint division is performed,
The apparatus is configured to include a position determination circuit that determines whether or not the line segment passes within the range based on the positional relationship of the regions in which the starting point, middle point, and end point of the divided line segment are located.

[Industrial application field]

The present invention deals with picking (figure selection) when a figure on the screen is interactively selected during the operation process of creating a figure using a figure processing system such as CAD, and the figure is edited such as moving, enlarging, or reducing the figure. Regarding circuits.

The graphic processing system is used for boat fishing, as shown in FIG.
Memory 30. Display 31. Keyboard 32. Input pen 33. Tablet 34. It consists of a processor 35, etc., and the operator points the figures on the CRT screen.
By specifying an area on the screen with a device (e.g., mouse, tablet, etc.), a figure that intersects with the pink area centered at the coordinates (the size of the rectangular area from the center in the X-axis and Y-axis directions is set in advance) will be created. selected. In other words, a circuit is required to quickly determine whether or not the above-mentioned pink area intersects with the figure on the screen.The speed of figure selection is particularly related to operator productivity, and further speeding up is required from the field of application. is required.

[Conventional technology]

Conventional picking circuits can be broadly classified into three types.

The first is an extension of the DDA circuit used to display line segments. The DDA circuit is a circuit that generates a point on a line connecting two specified points, and is used when displaying a line segment on a CRT.

In the case of picking, instead of writing the output of this circuit to the frame buffer, it is directed to a circuit that determines whether the output point is within the pink range.

According to this circuit, it is necessary to determine whether all points on the line segment are included in the pink range. Furthermore, the processing time required is about the same as that for display.

The second method is to use a clipping circuit independently of line segment generation in the DDA circuit, which ultimately uses the boundary line of the pick range to determine whether the line segment intersects with the pick range. Calculate the intersection with the minute.

This circuit enables pink determination without generating points on the line segment by determining the positions of the starting point and end point of the line segment with respect to the pick range. Pick determination is performed in the following order.

(1) Divide the outside and outside of the pick range into nine regions shown in FIG. 8, and give each a 4-bit code.

(2) Check where the starting point and ending point of the input line segment are in the nine divided areas, and perform the following processing.

(b) Take the AND of the codes at the start point and end point, and the result is 0.
If it is not 000, the line segment is outside the pick range and will not be picked.

([I) If the code of the start point or end point is 0000, the code ooooO point is within the pick range and is picked.

(c) In cases other than the above two cases, there is a possibility that the line segment intersects with the pink range, so the intersection between the line segment and the boundary line of the pink range is found, and if an intersection exists, it is picked.

This method requires a divider to calculate the intersection of the pick range and the line segment.

The third method uses the midpoint division method to calculate the intersection point, and although a divider is required to achieve part (c) in the second circuit above, this can also be achieved without a divider. This is a circuit that uses the midpoint division method to make it possible.

As shown in Figure 9, the midpoint division method first divides the area between the starting point and the ending point into two to find the CI, and then finds the midpoint C3 between that point C1 and the starting point. By repeating the division, the point of intersection with the boundary of the pick range is found; for example, in FIG. 9, it is found that C5 intersects with the boundary. In cases other than (a) or (b) in the second circuit, there is a possibility that it intersects with the pick range, so divide the line segment into two at the midpoint, and for each line segment (a) ~
Perform method (c).

In this midpoint division method, midpoint division must be repeated until an intersection is found.

[Problem to be solved by the invention]

Each of the above circuits has its own drawbacks.

The first circuit must determine whether all points on the line segment are included in the big range. Furthermore, the processing time required is about the same as that for display.

The second circuit requires a divider to calculate the intersection of the big range and the line segment.

The third midpoint splitting method requires repeating midpoint splitting until an intersection point is obtained.

The present invention was created in view of these problems, and
By improving the midpoint division method, it is possible to determine whether or not the midpoint division intersects with a big area based on the positional relationship between the midpoint and the corresponding start and end points, without having to repeat the midpoint division until an intersection is obtained. It is an object of the present invention to provide a picking circuit that speeds up picking processing through determination and makes graphic selection in graphic processing such as CAD more efficient.

[Means to solve the problem]

Means for solving the above problems in the present invention includes a code calculation circuit that divides the periphery of a predetermined range into a plurality of regions and calculates the regions where the start point, end point, and midpoint of the line segment are located;
A picking circuit that selects a figure within the range and includes a code determination circuit that determines whether a line segment passes within the range based on the positional relationship between the areas where the start point and the end point are located. Based on the positional relationship of the regions where each end point is located, it is determined whether the line segment passes within the range, and for line segments that cannot be determined by this, midpoint division is performed, and the starting point, midpoint of the divided line segment is The picking circuit is provided with a position determination circuit that determines whether or not a line segment passes within the range based on the positional relationship between the regions in which the point and the end point are located.

[Effect]

In the picking process using midpoint division, the present invention provides the following advantages:
By adding the determination of the positional relationship between the starting point, midpoint, and end point, unnecessary midpoint division is omitted.

FIG. 1 is an explanatory diagram showing the principle of the present invention.

As shown in the figure, whether or not the line segment connecting the specified start point and end point intersects with the big range can be determined by, for example, nine extension lines of the left end, right end, bottom end, and top end of the pick range. It is possible to determine based on the positional relationship of the starting point, middle point, and ending point with respect to the divided area. For example, if the positions are as shown in ■ to ■, it can be seen that they do not intersect. On the other hand, it is clear that the line segments in the positional relationship of ■ intersect. Also■、■
It is not possible to determine whether line segments with a positional relationship like this intersect or not based only on the information on the positions of the starting point, midpoint, and ending point, so it is necessary to perform midpoint division.

For example, assuming that the position code of the divided area is as shown in parentheses in FIG. 1, the position determination circuit performs the above determination as follows.

(2) Find the code of the midpoint (the codes of the start point and end point are found in advance).

■) If the code of the midpoint is 0000, the midpoint is included in the pick range, so it is jacked (in the case of ■).

(2) If the logical product of the codes at the start point and the middle point is not 0000, one of the following results will be obtained by the logical product of the codes at the end point and the middle point.

If the logical product of the end point and midpoint codes is also not 0000, there is no possibility that the line segment will intersect with the big range, so it will not be surprised (in the case of ■ to ■).

If the logical product of the end point and midpoint code is oooo, if the start point and midpoint have the same coordinates, it will not be pink, and if they do not, the midpoint will be used as the new starting point, and the midpoint between the new starting point and the end point will be calculated.■)
Repeat from (■).

■) If the logical product of the start point and midpoint code is 0000, if the end point and midpoint have the same coordinates, they will not be pink, and if they do not have the same coordinates, the midpoint will be used as the new route point and will be between the start point and the new route point. Find the points and repeat from ■) (in case of ■).

In this way, even line segments that obviously do not pass within the big range, such as the line segments ■ to ■ in Figure 1, could not be determined until the midpoint division was repeated until the division became impossible. In contrast, in the present invention, line segments that do not pass within the big range are determined more quickly based on the positional relationship of the start point, middle point, and end point, so that figure selection can be made more efficient.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a schematic block diagram showing an example of a display device embodying the present invention. As shown in the figure, the communication control circuit 11 provides data sent from the host computer 10 to the display processor 12, and the display processor 12 stores the data provided from the host computer 10 in the data RAM 15. It is output to the coordinate conversion circuit 16. The coordinate conversion circuit 16 enlarges, reduces, rotates, and translates the display data (x, y, 2) output from the display processor 12. The data outputted from the coordinate conversion circuit 16 is given to a clipping circuit 17, which clips the line segment that protrudes from the display area, and gives the clipped result to a straight line generation (DDA) circuit 19. The straight line generating circuit 19 generates points on the line segment connecting the starting point and the ending point outputted from the clipping circuit 17 and writes them into the frame memory 20. Each dot data stored in the frame memory 20 is given to a monitor interface 21, and the monitor interface 21 reads out the dot data on the frame memory 20 and supplies it to the CRT 22 together with a synchronizing signal. Therefore, graphics are displayed on the CRT 22.

Next, the flow of control of the present invention will be explained.

When the mouse 31 or tablet 32 is operated, the display processor 12 is notified of the coordinate values.

The display processor 12 places a cursor 23 as shown in FIG. 2 at a position on the CRT corresponding to the notified coordinate values.
Display. The operator is 1. Operate the mouse 31 or tablet 32 to place the cursor 23 on the shape you want to select.
When the display processor 12 is notified that the button on the mouse 31 or the tablet 32 has been pressed, the display processor 12 starts the pick process. First, the state is changed to pick mode, and then the graphic data stored in the data RAM 15 is sequentially output to the coordinate conversion circuit 16. A coordinate conversion circuit 16 converts the coordinates of graphic data. In the case of the big mode, the coordinate-transformed data is output not to the clip circuit 17 but to the pick circuit 18 of the present invention, and the big circuit 18 determines whether the graphic data intersects the pick range and outputs the result. to the display processor 12. If the determination result is "picked", the display processor 12 notifies the host computer 10 of the graphic data information.

If the determination result is not "vicked", it is determined whether or not the next graphic data is to be pinked.

FIG. 3 is a specific configuration diagram of the big circuit 18 shown in FIG. 2. In the figure, the bit circuit 18 is
Code determination circuit 242, position determination circuit 25, code calculation circuit 26. and registers for registering values of start point coordinates, start point code, end point coordinates, end point code, midpoint coordinates, midpoint code, and pick range.

When the pick circuit 18 is notified of the coordinates of the starting point and ending point of the line segment to be pink, first, the code calculating circuit 26 calculates the codes of the starting point and ending point. FIG. 4 is a flowchart showing the processing of the code calculation circuit 26.

The code refers to the space in which a figure is defined, as shown in Figure 8, at the left and right ends of the specified pick range.

This shows where a designated point is located in the nine areas when the area is divided into nine areas at the top and bottom ends. Each area has a 4-bit code, and when each bit is 1, the 4 bits have the following meanings.

The two vertices of the first bit are to the left of the left edge of the pick area.

The second bit two vertices are to the right of the right edge of the pick area.

Third bit: The vertex is below the bottom edge of the big area.

The two vertices of the fourth bit are above the top of the big area.

Next, using the code obtained by the code calculating circuit 26, the code determining circuit 24 determines whether the specified line segment is picked. FIG. 5 is a flowchart showing this process.

■Take the logical AND of the codes at the start point and end point, and the result is oo
If it is not oo, the line segment is outside the pink range and will not be picked.

(2) When the code of the start point or end point is oooo, the line segment is picked because the point whose code is oooo is within the pick range.

(2) If it is not possible to determine whether or not the image should be pinked by the determinations (2) and (2) above, the position determination circuit 25 of the present invention performs a pink determination. FIG. 6 is a flowchart showing the processing.

l) Calculate the coordinates of the midpoint and obtain the code using a code calculation circuit.

The coordinates (x, y) of the midpoint are x - (Start point X + End point X) ÷ 2 y = (y of the starting point + y of the ending point) ÷ 2 It is.

(2) If the code of the midpoint is oooo, the midpoint is included in the pick range and is picked.

(2) If the logical product of the starting point and middle point codes is not 0000, it is divided into three ways. If the logical product of the end point and midpoint codes is also not oooo, there is no possibility that the line segment will intersect the pick range, so it will not be pinked. If the logical product of the codes is 0000, if the starting point and midpoint have the same coordinates, they will not be picked. If the coordinates are not the same, the midpoint is set as the new starting point, the midpoint between the starting point and the ending point is found, and the process is repeated from 1).

(2) If the logical product of the starting point and middle point codes is 0000, it can be divided into two ways. If the end point and midpoint have the same coordinates, they will not be picked. If the coordinates are not the same, the midpoint is set as the new end point, the midpoint between the start point and the end point is found, and the process is repeated from I).

In this way, the code determination circuit 24 determines whether or not it is picked, and notifies the result. As described above, in this embodiment, since it is determined during the examination what is obviously pink and what is clearly not pink, the processing time is significantly reduced compared to the conventional method.

〔Effect of the invention〕

As explained above, according to the present invention, the midpoint division method is improved, and the midpoint division can be performed without repeating the midpoint division until an intersection point is obtained, and the positions of the starting point and the ending point corresponding to the midpoint. It is possible to provide a picking circuit that speeds up the picking process by determining whether or not it intersects the pick area based on the relationship, and makes graphic selection in graphic processing such as CAD more efficient.

26; Code calculation circuit.

[Brief explanation of the drawing]

Figure 1 is a detailed explanatory diagram of the present invention, Figures 2 and 3 are configuration diagrams of an embodiment of the present invention, and Figures 4 and 6 are
7 is a block diagram of a general graphic processing system, FIG. 8 is an explanatory diagram of a general determination process, and FIG. 9 is an explanatory diagram of the conventional midpoint division method. 18; pick circuit; 24; code determination circuit; 25; position determination circuit; Fig. 2 is a block diagram of an embodiment of the present invention; Fig. 3 is a block diagram of one embodiment of the present invention; Flow diagram 5

Claims (1)

[Claims] The periphery of a predetermined range is divided into a plurality of regions, and the starting point of a line segment,
A code calculation circuit (26) that calculates the area where the end point and the middle point are located, and a code judgment circuit (24) that determines whether the line segment passes within the range based on the positional relationship of the area where the start point and the end point are located.
), the picking circuit (18) selects a figure within the range, and determines whether a line segment passes within the range based on the positional relationship of the regions in which the start point, middle point, and end point are located. Then, for line segments that cannot be determined by this, midpoint division is performed,
It is characterized by comprising a position determination circuit (25) that determines whether or not the line segment passes within the range based on the positional relationship of the regions in which the starting point, middle point, and end point of the divided line segment are located. picking circuit.