Game Development Reference
In-Depth Information
It is
Jordan curve theorem
reimplemented in Ruby. Looks ugly, but it actually works, and
is pretty fast too.
Also, this works on more sophisticated polygons, and our tank is shaped more like an H
rather than a rectangle, so we could define a pixel perfect polygon. Some pen and paper
will help.
class
TankPhysics
<
Component
#...
# Tank box looks like H. Vertices:
# 1 2 5 6
# 3 4
#
# 10 9
# 12 11 8 7
def
box
w
=
box_width
/ 2 - 1
h
=
box_height
/ 2 - 1
tw
= 8
# track width
fd
= 8
# front depth
rd
= 6
# rear depth
Utils
.
rotate(object
.
direction, x, y,
x
+
w, y
+
h,
#1
x
+
w
-
tw, y
+
h,
#2
x
+
w
-
tw, y
+
h
-
fd,
#3
x
-
w
+
tw, y
+
h
-
fd,
#4
x
-
w
+
tw, y
+
h,
#5
x
-
w,
y
+
h,
#6
x
-
w, y
-
h,
#7
x
-
w
+
tw, y
-
h,
#8
x
-
w
+
tw, y
-
h
+
rd,
#9
x
+
w
-
tw, y
-
h
+
rd,
#10
x
+
w
-
tw, y
-
h,
#11
x
+
w,
y
-
h,
#12
)
end
# ...
end
To visually see it, we will improve our
draw_bounding_box
method:
