JPS63318633A - Digital differential analyzer - Google Patents

Abstract

PURPOSE:To allow a thick line whose end point is vertical to a straight line direction to draw at high speed, by providing a Y start point counter, an X start point counter, a K residual register and plural multiplexers, etc., and executing a start point calculation corresponding to the inclination of the straight line. CONSTITUTION:When a thick line from a start point P0 (x0=0, y0=0) to an end point Pn (xn=10, yn=5) is drawn first of all, a line of P0-Pn is drawn, and subsequently, a line being vertical to the line of P0-Pn is drawn, and subsequently, a line being vertical to the line of P0-Pn, and also, passing through P0 is drawn, and X and Y coordinate values of the start point derived on its line are set. That is, first of all, a Y start point counter 206 is decreased by '1' by a control circuit 201, and subsequently, a multiplexer 208 selects a K register 204, and a multiplexer 209 selects a K residual register 207 and executes addition by an adders 106, and writes its result in the register 207. Next, the counter 206, and the X start point counter 205 shift a value to a Y counter 102, and an X counter 101, respectively, and the initialization is ended. Since each straight line is drawn successively, the thick lines whose end points are vertical to the line direction can be drawn at high speed.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a digital differential analyzer (hereinafter abbreviated as DD) that calculates coordinates in order to draw a straight line of arbitrary thickness between two arbitrary points. ◎Conventional technology There are almost no conventional graphic devices that draw lines of arbitrary width using the rask display method.1Normally, as shown in Figure 7, a rectangular frame is cut horizontally and both end points are calculated. A method of filling in horizontally @ Problems that the invention aims to solve This method is good when the rectangle is lying horizontally, but when the rectangle stands up, the number of lines to be drawn increases, and this can be handled by software. The invention was made in view of this point and aims to draw thick lines at high speed.Means for solving the problemThe present invention solves the above problem by A counter is provided in the system to store the starting point coordinates, and by determining the next starting point from a component perpendicular to the line to be drawn, a plurality of straight lines with the same inclination are drawn side by side and a thick line is drawn. By storing the initial state that was drawn last time and calculating the initial state to be drawn next using the above configuration, it is possible to calculate the initial state to be drawn next using multiple straight lines with the same inclination and the position of the starting point in the direction of the thick line to be drawn. ◎ Embodiment In general, the DDM is the line segment P shown in FIG. 2. -Pn straight 11i
It calculates on which grid point to place a point to draw I. ◎ The block diagram of DDM for drawing a straight line is shown in the third
In the initial state shown in FIG.
01iXo value,! In the example of FIG. 2, where the counter 102 is set to a value of 10 and the residual register is set to a value equal to the value of the tangent of the τ axis at the starting point and the part below the decimal point, the X counter 101 is set to 0. ! The counter 102 is also 0. Residual register 1
04 is also 0 ◎Register 10 that holds the value of Δy
3 is the value of the linear equation 〇).

The adder 105 is configured to perform addition after the decimal point, and when a carry signal to 1 is output, the τ counter 10211
Count up 〇 Once the initial settings are complete, calculations are made to find each point on the clock. - After each calculation, the X register 101 and ! The boxes in registers 10 and 2 are the grid points to be found.The table below shows the values of each counter and register as the clock changes.Table 1
〇 As shown in Figure 3, in the drawing of the DDM, a line with the thickness of one dot is drawn. As shown in Figure 4, from the starting point P0 to the ending point Pn! P, shifted by -1 in one direction. - Consider the P and φ lines anew. This P. - Calculate the point to be drawn using DDM for the line P, n in the same way as before.◎This P. - PIN Yoshi more! Consider the line P2O-P2H shifted by -1 in the axial direction, and similarly calculate the points to be drawn with DDM. ◎The number of these lines to draw depends on the width of the thick line you are trying to draw now. It's decided O By drawing like this, you can draw a line with the desired thickness, but
The end point of this thick line is not perpendicular to the line to be drawn,
This results in end points cut along 1tllK.@ In the present invention, each starting point P,. By starting from an appropriate position and drawing the same number of points as the po-pn drawing points, a thick line with end points perpendicular to the line direction is drawn. - Shifting the starting point ◎po
- perpendicular to the line pn and point P. Draw a line pos through ・Each line segment I Plo-Pln * P2O-P2n I
P. -PlB... and line P. -8 intersects P
, 8°P21, PCB... is the position where you want the original starting point of each line segment ◎ However, the point is not on the grid, but P1! i l PH1, P51
The starting point P on the grid is obtained by converting the X coordinate value of 1... into an integer. .

The X coordinate value of P'2゜, P'so ...... can be obtained @ By the way, the X coordinate value of P1B I P2B""""I"
s 1 "2!!lX51... is X. From (:
lC1! ! You can see that it is the same as sequentially adding the values of -X, )== 〇 This shows that the starting point P: on the grid point. ,P;. .

p/,. The X coordinate value of ... can be calculated by repeating the addition to 9 in DD mode. ◎ Starting point P:. ,P;. , P'3°... To find the X coordinate value of the song, I "1G", "201 "50 """ X coordinate value "1G".

When "20, If the value of shi also increases by one, the starting point Pm-1° of the line drawn just before!
The value CY'Tm-+ is obtained by subtracting 1 from the value of the coordinate y'm-1°.
. -1), and then calculate the starting point p' of the line drawn immediately before
,,. Add ay to the value of the residual register of DDmu at (i.e., the value of the residual register in the initial state of DDmu of the line drawn just before), and set the value after the decimal point of the result to the value of the residual register of DDmu at the current starting point. Set it as the initial value of the residual register, and if the previous addition result exceeds 1! The coordinate value 3”no is (y;,.-1) plus 1 (y, -1°-1) +
1, and if it does not exceed 1, y-0t(ym-,'
. -1), if the value of 0"so is the same as the value of the previous x complex 10, then 7'160 is y', and -1, and the initial value of the residual register is the value of KJa just before. Make it the same as the value of the residual register in the initial state of the line.

As above x:. ,y:. 8"20.1'2゜...
By setting ... as the initial state of each residual register, the start and end points of the thick line to be drawn as shown in Figure 6.

The end point perpendicular to this thick line is ◎ By the way, the value of = (x, g - xo) is determined by the following formula ◎ Also, the number of lines to be drawn is given by setting the drawing width to D.

FIG. 1 is a block diagram showing an embodiment of the DDM of the present invention. 0 Starting point P in FIG. 6. A case of drawing a thick line with CX (7=0.7o=O) end point Pn (Xn=10.7n=5) and thick line width D=e will be explained. The DD system of the present invention is controlled by the control circuit 201. Oshi,
There is a period for drawing as in the conventional DDM, and a period for setting the initial state at the starting point of each line drawing. First, the initial state at the beginning of thick line drawing.

That is, the starting point P. In this state, the value of the N register 202 is set to xn-xo=10, and the L counter is set to (3).
) is set to 7. Register 204 is set to 0.4 according to @) formula, and register 103 is set to 0, the value of ay.
．． 5, the X counter 104 and the I starting point counter 20g are X. The value 0 is set for ! With counter 102!
The starting point counter 208 is y. The OX residual register 207 to which the value 0 is set is 0, and the residual register 104 and the starting point residual register 207 are P. The residual value of 0 is set to 0. First, this DDM is similar to the DDM shown in FIG.
0 multiplex t208 which operates to draw the source of
selects register 103t and also selects multiplexer 2
09 selects the residual register 104, calculates with the adder 106, and writes the addition result to the residual register 104 with the 6 clock from the control circuit 201. At the same time, the X counter 101 is counted up by 1 with that clock. . The 6-carry up signal to 1 of the adder 106 is connected to the Y counter 102 by the gate 211 and becomes 91.
If a carry signal occurs! Counter 102 is counted up by 1 @ Control circuit 201 only has the value of N register 202.

Sends a clock to the residual register 104 and the X counter 1o1. As a result, po-pn drawing is executed.
Then, the L counter 203 is decremented by 1 to set the initial state of the line to be drawn.

First, the control circuit 201 starts the I starting point counter 206'ik.
Reduce by 1.

Next, the multiplexer 208 selects the register 204, the multiplexer t209 selects the residual register 207, and the adder 106 performs addition.

Write the result to the X residual register 207 - In this addition, a carry signal to 1 may or may not occur, but if a carry signal to 1 occurs, the carry signal to 1 is a game) 210 through #) x starting point counter 20! 'i1
Count up. At the same time, the control circuit 201
Multiplexer 208 selects Q raster 103, multiplexer 209 selects starting point residual register 207,
The adder 105 adds the result and writes the result to the residual register 104 and the starting point residual register 207. ◎If there is a carry signal from the adder 106 to 1 at that time, the gate 211k
Increment the Y start point counter by 1.

If a carry signal to 1 does not occur in the result of addition of the register 204 to the residual register 204 shown above, the multiplexer 20B selects 0, the multiplexer 209 selects the starting point residual register 207i, and performs the addition. vessel 10
6 through the residual register 104 and the starting point residual register 20
Write to 7.

After these operations are completed! The starting point counter 206 transfers the value to the Y counter 102, and the X starting point counter 207 transfers the value to the When only the value of N register 202 is calculated, the L counter is decremented by 1.
The process repeats 0 or more, which is the period for setting the initial state of the next straight line, and ends when the L counter becomes negative.

The flow of processing is 0, which indicates the value of each counter and register at the starting point of each straight line drawn in the next narrowest direction.

The starting point and residual are calculated as described above, and a thick line is drawn.

The above explanation was given in the range of tilt of 0 to 45 degrees, but
It is possible to draw any slope by exchanging the direction and the Since it is done using a system, it is possible to draw thick lines at high speed, which is extremely useful in practice.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a DDM according to an embodiment of the present invention;
Fig. 2 is an explanatory diagram of the DDM, Fig. 3 is a block diagram of a general DDM, Figs. 4, 6, and 6 are detailed explanatory diagrams of the present invention, and Fig. 7 is an explanation of the prior art. 0 101...X counter, 206...X
Starting point counter, 1o2...τ counter, 206
・River...Y starting point counter, 103...dy register, 2o4...X register, 106...
...Adder below the decimal point. Alfl 0 sword 104... Residual register, 207...
Starting point residual register, 2o7... KPM register, 202... Publication register, 203...
L register, 201... Control circuit ◎ Name of agent: Patent attorney Toshi Nakao and one other person: 2
Figure off 1 3 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] an adder for adding values of the slope of a straight line to be drawn; a first register for storing the addition result of the adder; a first counter operated by a carry signal of the adder; and a first counter operated by a clock. A digital differential analyzer that has two counters and performs drawing using the outputs of the first and second counters as coordinate values, and means for adding the value of the vertical slope of the straight line to be drawn using the adder. , second and third registers that store the addition results of the adder, third and fourth counters that operate according to the carry signal of the adder, and the first and second counters that store the addition results of the adder; 3rd and 4th
A digital differential analyzer, characterized in that it has means for setting the value of a counter.