You can approximate a line with multiple AR.Circle or AR.ImageDrawable objectes. Using offsetX/offsetY it is possible to position them on the image target. However you will only be able to "play" on the same plane as the target image. There is no possibility to know where it hits the side of the screen.
Your game idea sounds interesting, thus just let me know if I can be of any further help to make it a reality.
over 5 years ago
I'd like to draw a line in the camera view that "points" in the same direction/orientation in 3D space as the recognized image. In my ideal world, I'd even like to reflect the line off the corners of the screen based on the angle in which it hits the edge of the screen. Imagine a "Pong" or "Breakout" type game where the intial path of the ball is deterined by the recognized image.
"Bouncing" off the sides of the screen won't work, since I won't know the angle of incidence.
The HtmlDrawable bounces around a lot, whereas all I really need would be a snapshot of the position/orientation of the tracker once I click it and then some way to use this information to plot a line (or animate a moving ball) through the 3D space along the desired path.