Drawing in e15:oGFx

We all have complained at some point about how limited the mouse is. But, is it? The two dimensional single point mapping of mouse interactions can seem like a poor way to interact with the multidimensional, information rich virtual space displayed in our computer screens today. It is true, having to click through thousands of web links to see the online pictures of all of my friends is definitely more painful than seamlessly navigating through a sea of pictures, dragging flocks of them as if I was using an invisible fishing net, and arranging them back together in spatial ways that could tell me not only about them as particular pictures or sequences of pictures, but as non linear narrative snapshots of time, experience and memory.

However, when thinking about experience and interaction, overwhelming your subjects with too much input can become a problem, and it is especially hard to design experiences that can be interaction rich and at the same time make sense. The world and our perception are a perfectly balanced system where everything seems coherent and accessible to our senses, at least most of the times, but when it comes to manipulate tools with a specific goal in mind, narrowing interaction down to the minimum gives us the advantages of focus and control. When drawing for example, every single artist in history has used the single point touch of the charcoal, pencil, pen or brush over a flat surface, performing a slightly different gesture, but just as limited, than the one imposed by the mouse. When creating a drawing with the pencil or the mouse, the differences come from the reactions of the material (paper or similar for the pencil, and computer for the mouse), and not from the devices. A mouse can be given the shape of a pencil, and used over a pressure sensitive display, it responds to the drawing gesture just as a pencil would.

Because of this reason, and because the human drawing gesture is a perfect source for random input, we have introduced mouse input into oGFx. There are several different ways to draw in oGFx. The drawing gesture can be mapped from screen coordinates to 3D coordinates in the OpenGL context or 2D coordinates in the Quartz2D context. We started by making the raw screen coordinates available to the python interpreter, so the decision of what to do with them could be taken by the programmer of the drawing experience.

I wrote a few scripts that map the screen coordinates to Quartz2D coordinates, adding some behavior to the strokes, a simple implementation of the Bresenham line algorithm, and a low resolution canvas. I have been working with simple drawing tools for a while, and I found oGFx to be a refreshing platform to experiment with, specially because of the four following reasons: I can change the definitions in a script without having to stop the program (or even stop drawing), I can draw and navigate around a drawing in 3D at the same time, I can apply and remove CoreImage filters on the fly, and I can project the action of drawing over history. Even though all these reasons are some of the important features of oGFx that we have been using from the beginning, they were not combined with hand drawing until recently.





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