Re: Reflecting a ray off a line

Richard schrieb:
> I'm absolute beginner to computer graphics. I'm just seeking hints to
get a
> feel for the nature of the task. I'm talking about 2D graphics. I'm not 
> seeking someone to do the task for me.
> 
> Lets say there is a line (line segment) and I wanted to get the computer
to
> draw a ray that reflected off the line at the angle of incidence to the
> line. Like a light ray hitting a flat mirror.
> 
> In just basic terms, what is required enabling the computer to end the
ray
> at the line intersection, and then draw another line segment (that
continues
> the ray), starting from the intersection and in the proper direction?
> 


1. define your line segment (most likely using point1 and point2)
2. define your ray (most likely using an origin and a direction)
3. calculate the intersection point between line segment and ray
4. create 2nd ray (the reflection ray)
	a. with the calculated intersection point as origin
	b. the direction can be calculated using the law of reflection
	   (basically this equation R = 2 · N ·(N dot -D)+D ; where R is 	 
the new direction, N the normal of the line segment and D 			    the 
incoming ray direction)


**** till here this is all mathematically and no drawing involved ****

5. draw your line segment
6. draw the first ray from its origin to the intersection point
7. draw the second ray from its origin to an arbitrary point in the ray

Regards
Dieter


> I think the basic task is drawing a polyline. That is the ray. I think
it
> might also involve testing the state of pixels. Well, how does the ray
stop
> at the line and then start off in a new direction? Is it something to do
> with reflection vectors?
> 
> I am trying to employ  managed code / VB or C# / .NET libraries.
> 
> Signed
> 
> "Completely out of my depth on this."
> 
> 
> 
> 
> 
>