I am using a 1280x720 black and white image of a triangular-type shape which I would l like to mask images generated in quartz. The triangular shape is 100% white and the black 0% and at this stage i'm not using a gradient for simplicity. The shape is to make a kind of movie projector lightbeam throw effect. When I attach the image to the billboard Mask input, I don't get a clean edge – the black areas in the mask images show up just not as brightly as the white masked areas. I'm looking for a sharp clipping mask edge. I tried to workaround with various composite patches (Darken and Multiply seemed worth a spin) prior to the billboard (and illiminating the need for mask) which only has confused me more and raised more questions in regards to matching image dimension (Resize and Crop patches). Because of other elements on the screen I'm looking to use Over blending mode. There must be a straight forward way to apply an alpha to an image to get a clipping mask but i'm from the the land of Adobe products etc, not Computer Science, so I'm stumped in QC again
Mask.qtz
Description: application/quartzcomposer
Also on those other question: When hovering the cursor over a patches' image output port (not so easy with a tablet BTW Apple) an image preview is generated along with dimensions expressed as {a,b,c,d}. c and d seem to be the image dimensions but as for a and b they are often negative so are they the locating co-ordinates?? If they are, how to get a image matching the same location and size as another is beating me also.
Those values express the Origin (x = a, y = b) and Size (width = c, height = d). The origin is important if you're writing CoreImage Filters, since many filters will expand an image a bit, causing the origin to go negative. (There are other reasons why this happens too -- I don't deal with image processing much, so I can't pencil in many more details of why this is or why it's important).
-- [ christopher wright ] [email protected] http://kineme.net/
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