Monthly Archive: December 2011

Dynamically Dimensioning 3D Models

Open /scripts/analysis-and-simulation/dynamically-dimensioning-3d-models

When interactively manipulating objects in 3D, having clear dimensions that update dynamically while dragging around allows for much greater confidence and accuracy in the process. This is especially true on a tablet where accurate alignment is well near impossible as your finger (and sometimes hand) effectively obscures the drag point. However, what started out as a quick experiment ended up sucking me into a 6 day vortex, swirling around with quaternion maths and 3D text manipulation in an attempt to get radial dimensions visible when viewed from any direction. This tiny applet is the result of those 6 days.

A gluUnproject() Function for P3D and OPENGL Sketches

Open /scripts/analysis-and-simulation/gluunproject-function-for-p3d-and-opengl-sketches

I have been struggling for a while in Processing with the reverse projection of 2D screen coordinates back into 3D world coordinates. It's relatively straightforward in OPENGL sketches using the JOGL view matrices and the GLU.gluUnproject() function. However, I could never get anything solid when using the P3D renderer or the PGraphics3D matrices. For some reason there was always a slight scaling issue which varied with different views. Previously I've used fudge factors to get it pretty close but, as I still prefer P3D for browser embedded work, I finally spent some time on it and made the breakthrough I needed. This is a brief description of what I learnt along the way as well as a demo applet and custom gluUnproject() function.