Computer graphics, how to calculate the line outside a little to the line

Horizontal intersection, vertical intersection, and any Angle of intersection point by point and a line?

Or calculated vertical (horizontal) straight line intersection of straight line and the picture?

CodePudding user response:

Using SVG explanation

CodePudding user response:

Use the formula directly calculate!
Plane of two straight lines intersecting with a direct calculation formula
Know the slope of a straight line, and its vertical straight line of slope is also know
Some oblique type equation can be established
A linear equation, it is easy to calculate the intersection