Line plotting method
View Patent ↗A line plotting method for plotting lines whose coordinates are given on a display screen on which pixels are arranged according to a prescribed rule, the method includes correcting coordinates at the end point of a line on the basis of which the end point is a starting point or an ending point or whether the end point is inside a prescribed frame determining whether a direction from a starting point of a line after correction toward its ending point horizontally or vertically is the same as a direction from a starting point before correction of a line toward its ending point determining whether integer values of the coordinates of starting and ending points after correction are the same when directions from starting points after and before correction of a line toward their ending points are not matched.
1. A line plotting method comprising:
a first correcting, using a plotting device in a graphic chip, of a first axis coordinate of a starting point or an ending point in accordance with a pixel of a prescribed frame intersecting a line having the starting point and the ending point,
wherein the first axis coordinate corresponds to a greater of a first difference and a second difference, the first difference being a difference between X-coordinates of the starting point and the ending point and the second difference being a difference between Y-coordinates of the starting point and the ending point of the line; and
a second correcting, using the plotting device in the graphic chip, of a second axis coordinate of the starting point or the ending point by adding or subtracting, respectively, a calculated value to the second axis coordinate,
wherein the calculated value is determined based on a product of a moving distance of the first axis coordinate and an inclination value of the line.
2. The line plotting method according to claim 1 , wherein:
an axis corresponding to the first axis coordinate is a first axis and another axis corresponding to the second axis coordinate is a second axis; and
the first axis coordinate of the starting point or the ending point is corrected up to one pixel back to a previous pixel or one pixel back to a center of the previous pixel.
3. The line plotting method according to claim 1 , wherein the prescribed rule is a Diamond Exit Rule and the prescribed frame is a Diamond frame.
4. The line plotting method according to claim 1 , wherein a car navigation system can be used for implementing the line plotting method.
5. The line plotting method according to claim 1 , further comprising determining, using the plotting device in the graphic chip, whether a first direction from the starting point of the line toward the ending point after the first and second correcting is same as a second direction from the starting point of the line toward the ending point before the first and second correcting.
6. The line plotting method according to claim 5 , further comprising plotting pixels, using the plotting device in the graphic chip, on a display screen in response to the first direction being same as the second direction.
7. The line plotting method according to claim 1 , further comprising determining, using the plotting device in the graphic chip, whether a first direction from the starting point of the line toward the ending point after the first and second correcting is different from a second direction from the starting point of the line toward the ending point before the first and second correcting.
8. The line plotting method according to claim 7 , further comprising determining, using the plotting device in the graphic chip, whether integer values of the first axis coordinates of the starting and ending points after the first correcting are equal to each other in response to the first direction being different from the second direction.
9. The line plotting method according to claim 8 , further comprising plotting pixels, using the plotting device in the graphic chip, on a display screen in response to the first direction being different from the second direction and the integer values of the first axis coordinates of the starting point and the ending points being equal to each other after the first correcting.
10. A graphic device comprising:
a graphic chip;
a plotting device in the graphic chip, the plotting device being configured to:
correct a first axis coordinate of a starting point or an ending point in accordance with a center pixel of a prescribed frame intersecting a line having the starting point and the ending point,
wherein the first axis coordinate corresponds to a greater one of a first difference and a second difference, the first difference being a difference between X-coordinates of the starting point and the ending point and the second difference being a difference between Y-coordinates of the starting point and the ending point of the line;
correct a second axis coordinate of the starting point or the ending point by adding or subtracting, respectively, a calculated value to the second axis coordinate,
wherein the calculated value is determined based on a product of a moving distance of the first axis coordinate and an inclination value of the line; and
determine whether a first direction from the starting point of the line toward the ending point after correction of the starting point or the ending point is same as a second direction from the starting point of the line toward the ending point before correction of the starting point and the ending point.
11. The graphic device according to claim 10 , wherein the plotting device is further configured to determine whether integer values of the first axis coordinates of the starting and ending points after correction of the starting point or the ending point are equal to each other in response to the first direction being different from the second direction.
12. The graphic device according to claim 11 , wherein the plotting device in the graphic chip is further configured to plot pixels on the display screen in response to the first direction being different from the second direction and the integer values of the first axis coordinates of the starting point and the ending points being equal to each other after the first correcting.
13. The graphic device according to claim 10 , wherein the plotting device in the graphic chip is further configured to plot pixels on the display screen in response to the first direction being same as the second direction.