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Integrating Cylinder Targets in Plakar

September 3, 2014 - 3:27am #1

Hey Guys,

we are integrating cylinder tagets in our Vuforia based AR platform Plakar. We are facing some problems here since we are unfortunately no OpenGL experts. Our goal is to integrate the Video Playback with cylinder targets. So basically we would like to play back the respective video files projected on the cylinder model. For this ve have modifyed and integrated your Cylinder Target example. The video playback is actually working fine, but we have some problems with the texture coordinates. To illustrate this, i have replaced the video file with a static texture. As you can see, the coordinates (or maybe the UVs?) are somehow screwed up if we are using your unmodifyed code from the sample... In this screenshot the camera is facing the soda label, but as you can see evrything is inverted (the back of the label is in the front, left is right and up is down). Since OpenGL is really a bit of black magic for us, i hope that somebody could give us here a helping hand.

Here is the cylinder model and code responsible for rendering:
https://gist.github.com/smoku/04d3a42174d81532fbb8

Some other problems we are facing in our integration:

1. we don't need the cylinder caps on the top and the bottom, since we are just playing back the videos wrapped around a can or bottle. We tryed to get rid of them by uncommenting some lines in the code, but i am not sure if this is the right approach... Is there a way to make the top/bottom of the cylinder fully transparent (associate a transparent PNG maybe)? Or do we need a new model of a cylinder without the caps?

2. since we just need the front face of the cylinder could one of you guys give us a helping hand to enable the back face culling in the used shaders (iOS and Android)

3. a more general question (sorry if this is answered somewhere else in the forum): how should we construct our markers and videos if we would like to play back the video wrapped on the cylinder, but not covering the whole perimeter? For example only covering the lable of a bottle...

It would be extremely cool if one of you guys could give us a helping hand. It all this sounds like a lot of work, i would be more than happy if one of you OpenGL gurus would have some time for a little payed job - so just drop me a mail or PM here...

Cheers,

Sandor

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