Hello, I've recently purchased a Wacom Intuos graphics tablet. I am very pleased with GIMP's support for the tablet, and I've had a great time working with it. However, there's one obscure feature that still troubles me. I'm trying to make Image Pipes where the ranks are chosen according to the X-tilt and the Y-tilt of the Intuos stylus. The results I've gotten are pretty strange. I've written up a short document trying to describe what's happening, and I'm attaching it with this letter. Here are the explanations I see for what's been happening: 1. The driver I have for the Intuos is sending bad information. This is entirely possible. I downloaded a driver binary off the web. The site where I found it had no description of what the driver was or who wrote it. 2. GIMP support for X and Y tilt is a little buggy. I'd find this understandable. Image Pipes are a somewhat obscure feature, and X and Y tilt are an obscure feature of an obscure feature. So, I'd like to know whether X and Y tilt have been proven to work on other systems, and, if so, with what version of X and which drivers. I'm already very grateful to anyone who has worked on GIMP, and my thanks in advance to anyone who can help me with this issue.
Tilt Behavior Description This is a brief behavior of how the Xtilt and Ytilt behavior of the GIMP image pipes function. The machine I found this behavior on is a Redhat 7.0 machine with a 2.4 kernel and an Intuos USB Graphics tablet. The behavior of Xtilt and Ytilt is very similar, so I will describe Xtilt in this document, and the reader can imagine Ytilt as the same thing, only 90 degrees clockwise. When I refer to the tilt, I am referring to the angle of the stylus to the surface of the tablet. 0 degrees describes the tilt when the stylus is lying on the surface of the tablet pointing due east. 90 degrees is the tilt of the stylus when it is pointing directly at the tablet. 180 degrees is the tilt of the stylus when it is lying on the tablet pointing due west. When I refer to brushes, I'm referring to the individual segments of the image pipe. When an image pipe is saved to select brushes based on Xtilt, one of these segments will be chosen depending on the tilt of the pen. The first brush is the topmost layer when the image pipe is saved. The last brush is the bottom layer. The behavior I expect is that the tilt would be divided up between the possible brushes, with each brush taking an equal portion of the possible angles. For instance, if there were four brushes, the first brush would be chosen for a tilt of 0-45 degrees, the second brush for a tilt of 45-90 degrees, the third brush for a tilt of 90-135 degrees and the last brush for a tilt of 135-180 degrees. But the behavior I'm getting is this: If an image pipe has only two brushes, I find that the last brush is always chosen, no matter what the tilt is. If there are four brushes, the last brush is chosen when the tilt of the stylus is between roughly 60 and 180 degrees. I have tried using up to 25 brushes, and it appears the last brush always gets chosen for at least 90 degrees of tilt (half the possible angles). With 25 brushes, it seems that the 85-180 degrees of tilt result in choosing the last brush. It also appears that the first half or so of the brushes is never chosen.
