FAQ

FAQ

Working with Images

I'm displaying an Image in a Billboard, but it only takes up half the screen.

Make sure your Billboard has Width set to 2.

An Image doesn't work. When I mouse over it, it says "Infinite (needs cropping to render)".

Many of the Generators create infinite sized images (e.g. Constant Color, Checkerboard, etc). Pass this Image through an Image Crop patch and set the Crop Width and Crop Height to the size you want the Image. You can set Crop X and Crop Y to choose which part of the infinite image you want to crop, but you'll usually just leave these set to 0.

How do I create an image that's just a solid color?

Use Constant Color. You'll need to crop the image (see above).

How do I adjust the time on a video (i.e. to scrub through it)?

Drag a movie in from the Finder (or equivalently use the Movie Importer patch). Open the patch up in the Inspector and go to Settings (⌘2). Check "Asynchronous Mode". This will make the movie play sound and give you extra input controls.

To scrub through the movie, you'll need to dynamically adjust the movie's Selection Start (i.e. change the start time of the movie, expressed in seconds). However that's not all. Whenever you adjust the start time, you'll also need to flicker the Reset Signal pin on the movie. You can do this using a Watcher node. See the video scrubber.qtz example in additional examples.

My Render in Image patch is glitchy.

Put a Clear patch on the bottom layer inside your Render in Image. Otherwise anything that is "transparent" will show up as unpredictable video card artifacts.

Working with Numbers

I have a value that ranges between 0 and 1 but I want it to range between x and y.

You can use the Mathematical Expression patch to scale your value accordingly.

But because this comes up so often, and because QC doesn't have a linear map patch as it should (like map in Processing for example), I created a Linear Map macro that you can use. Find it in the utility folder.

I have a value that's kind of jittery (e.g. from Audio Input) and I want it to be smooth.

Use the Smooth patch. By adjusting the Increasing Duration and Decreasing Duration (expressed in seconds), you can adjust the "attack" and "decay" of the patch.

Smooth is also useful when hooked in to a boolean value (e.g. Mouse Left Button), which you can think of as a very jittery value that ranges between 0 and 1.

Other

How do I record QC output?

See class 3.