HTML and CSS Reference
In-Depth Information
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Figure 3-4.
The canvas element coordinate system
But wait, there's more! Let's measure some angles. In most systems, angles are measured
counterclockwise, with 0 degrees being shown as a line extending into the positive x axis, as shown in
Figure 3-5.
30 degrees
(positive)
-30 degrees
(negative)
Figure 3-5.
The usual angle measurements
Again, the canvas element has it backward, as illustrated in Figure 3-6. It rotates its angles clockwise as
they go positive.
Counterclockwise
means a negative angle.
