Game Development Reference
In-Depth Information
the
y
axis. If you start at the y-intercept, you can then arrive at a coordinate of
(1, 5). Here is how you calculate this value using the slope-intercept equation:
y ¼
2
x þ
3
y ¼
2
ð
1
Þþ
3
y ¼
2
þ
3
y ¼
5
The Point-Slope Equation
The previous sections reveals that if you start with the y-intercept and the slope of
a line, you can generate additional coordinate sets. When you determine points
in this way, you work with differences between the two sets of coordinates
(the deltas). As Figure 6.11 illustrates, you can always employ the differences you
find between the run and rise values of two coordinates to calculate the slope of
the line. At the same time, you can make use of a given point along with the slope
to determine the position of another point.
Figure 6.11
The slope remains a ratio between the rise and the run of a line.
