JPH02183877A - Graphic display device - Google Patents

Abstract

PURPOSE:To attain linear plotting at high speed by obtaining the maximum number of picture elements to have the same coordinates securely exists on a straight line to be plotted, based on inclination obtained by an inclination arithmetic means. CONSTITUTION:A long axis computation circuit 2 compares a distance DELTAx in the (x) coordinate between the start point and end point of the straight line to be plotted with a distance DELTAy in the (y) coordinate. Based on the result of this comparison, an inclination arithmetic circuit 3 executes division with the larger distance, out of the distances DELTAx and DELTAy, as a denominator and the smaller distance as a numerator and obtains inclination (m) of the straight line to be plotted. The maximum number of picture elements to have the same coordinates securely exists on the straight line to be plotted is obtained based on the inclination (m) which is obtained by this inclination arithmetic means. Thus, the whole time of the drawing can be decreased and as a result, the high-speed linear plotting can be promoted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a graphic display device having a bisotomaph display device and capable of displaying figures such as straight lines, and particularly to a graphic display device capable of drawing straight lines at high speed. It is.

[Conventional technology]

Conventionally, in this type of graphic display device, when drawing a straight line, address calculation and drawing of pixels on the straight line were performed pixel by pixel.

[Problem to be solved by the invention]

However, such conventional graphic display devices have the disadvantage that the drawing speed of straight lines is slow because address calculation and drawing of pixels on a straight line are performed pixel by pixel.

[Means to solve the problem]

The present invention was made in order to solve such problems, and it has N (N = natural number of 2 or more) with consecutive addresses.
a drawing means that simultaneously draws pixels as one unit; a masking means that prohibits drawing on any arbitrary pixel within the N pixels;
Distance Δx in the X coordinate between the start point and end point of the straight line to be drawn
and a comparison means for comparing the distance Δy in the y coordinate, and the above-mentioned Δx and Δ
A slope calculation means for calculating the slope m of a straight line to be drawn by dividing the distance between y using the larger one as the denominator and the smaller one as the numerator; and means for determining the maximum number of pixels having the same coordinates that reliably exist.

[Effect]

Therefore, according to the present invention, it is possible to reduce the total number of times of drawing.

〔Example〕

Hereinafter, the graphic display device according to the present invention will be explained in detail.

The figure is a block configuration diagram showing an example of this graphic display device. In the same figure, l is x of the start point/end point of the straight line to be drawn, X address (xs, ys)/(xe, y,
), 2 is Δx (Δx=lx, −
x, l) and Δy (Δy=IVsy, 1), Δ
When x≧Δy, the long axis of the X axis is Δx, and when Δy, the long axis of the Y axis is determined. 3 is the long axis of the Y axis (x
S-x, )/(ys -y-), for the long axis of the X axis (y
, -y, )/(x, -x,) as a slope m and outputs the value. 4 is a horizontal pixel number calculation circuit that outputs the value obtained by subtracting 1 from the integer part of II/ml as k. , 5 is long axis information, slope m, starting point X address gs, P.

An X address calculation circuit that calculates the X address for each pixel based on the point 9 is a display unit that sequentially reads and displays the contents of the frame buffer memory 8. Note that the horizontal pixel number calculation circuit 4 has If/
If the value k obtained by subtracting 1 from the integer part of ml is negative or O, then = 1, and if m = 0, = Iysyal
It has a function to output as .

Next, the X address calculation circuit 5. The functions of the mask generation circuit 7 and the frame buffer memory 8 will be explained together with the operations related thereto.

That is, in the case of the long axis of the X-axis, the X-address calculation circuit 5 calculates
During starting point or pixel address calculation, when the Y address changes from the Y address of the previous pixel, a continuous drawing instruction is given to the mask generation circuit 7, and the X address of the next pixel being calculated is set to the previous pixel. Find it by adding k to the X address of . At this time, the Y address is obtained by adding m-k. The mask generation circuit 7 refers to the X address and the presence or absence of continuous drawing I-rev, creates a mask information of N (N is a natural number of 2 or more) bits, and draws the necessary pixels.

From the mask generation circuit 7, Nb
Although it is possible to draw at the same time with 1t as one unit, if the required number of pixels cannot be drawn in one drawing, the mask information is recreated and the drawing is performed again. By repeating this, drawing is performed for the required number of pixels. At this time,
Mask information is determined so that the number of drawings is minimized. Note that the mask generation circuit 7 generates any bi in the above Nb1t.
It has a function to prohibit drawing for t.

The frame buffer memory 8 refers to the mask information Nb1t for the pixel address specified by the X address and the Y address and takes in data for the necessary pixel. The contents of the frame buffer memory 8 are sequentially read out and output to the display section 9 for display.

As described above, according to the graphic display device according to the present embodiment, when drawing a straight line, the maximum number k of pixels that reliably occur continuously at the same -Y address is determined, multiple pixels are drawn simultaneously, and pixels can be drawn in a small number of times. By drawing, the total number of drawings can be reduced, and as a result, the speed of straight line drawing can be accelerated.

〔Effect of the invention〕

As explained above, according to the graphic display device according to the present invention, N (N is a natural number of 2 or more) having consecutive addresses.
a drawing means that simultaneously draws pixels as one unit; a masking means that prohibits drawing on any arbitrary pixel within the N pixels;
Distance Δx in the X coordinate between the start point and end point of the straight line to be drawn
and a comparison means for comparing the distance Δy in the y coordinate, and the above-mentioned Δx and Δ
A slope calculation means for calculating the slope m of a straight line to be drawn by dividing the distance between y using the larger one as the denominator and the smaller one as the numerator; Since the present invention includes means for determining the maximum number of pixels having the same coordinates, the overall number of times of drawing can be reduced, and as a result, the speed of straight line drawing can be accelerated.

[Brief explanation of the drawing]

The figure is a block diagram showing an embodiment of a graphic display device according to the present invention. l...Input register, 2...Long axis calculation circuit, 3...
・Inclination calculation circuit, 4...Horizontal pixel number calculation circuit, 5...
・X address calculation circuit, 6...Y address calculation circuit,
7... Mask generation circuit, 8... Frame buffer memory, 9... Display unit.

Claims (1)

[Claims] a drawing means for simultaneously drawing N pixels (N is a natural number of 2 or more) having consecutive addresses as one unit; a masking means for prohibiting drawing on any pixel within the N pixels;
Distance Δx in the x coordinate between the start point and end point of the straight line to be drawn
and a comparison means for comparing the distance Δy in the y coordinate, and the said Δx and Δy based on the comparison result of this comparison means.
a slope calculating means for calculating the slope m of the straight line by dividing the distance between y using the larger distance as the denominator and the smaller distance as the numerator; A graphic display device comprising means for determining the maximum number of pixels having a certain value.