Check your alpha values to make sure they're doing what you think they will. Remember that if your alpha channel has a 0 value in any of the patches that create your effect that they may not render how you think they will if your app window actually allows alpha to be "clear".
For example, a "clear" patch which has a default value of vec4(0,0,0,0) will create a "clear"/see through effect when rendering to a window that allows alpha transparency. On Mar 2, 2013, at 5:14 PM, Gordon Apple <g...@ed4u.com> wrote: > I’m trying to implement a spotlight-type effect in a QCComposition presented > in a QCCompositionLayer. I want this to be implemented as a composition, > without mucking with the layer. I do change the layer’s scale and position > as needed. This is in a family of effects in which the user picks what .qtz > file to use. The QCCompositionLayer overlays the main presentation layers. > I want the QCCompositionLayer to dim everything behind it, leaving a clear > undimmed circle. > > I have been able to get this effect in the QC rendering view, using a > full-screen image billboard behind my effects billboard. However, when I use > it (without the full-screen image billboard ) in in the QCCompositionLayer in > my main program, the effect comes out reversed, i.e., the circle is dimmed > and the background is undimmed — obviously, not what I want. Any suggestions > as to how I can get the desired effect, preferably without changing the > QCCompositionLayer itself? > _______________________________________________ > Do not post admin requests to the list. They will be ignored. > Quartzcomposer-dev mailing list (Quartzcomposer-dev@lists.apple.com) > Help/Unsubscribe/Update your Subscription: > https://lists.apple.com/mailman/options/quartzcomposer-dev/gtoledo3%40gmail.com > > This email sent to gtole...@gmail.com
_______________________________________________ Do not post admin requests to the list. They will be ignored. Quartzcomposer-dev mailing list (Quartzcomposer-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/quartzcomposer-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
