Contain UVs

p2DContain.pde

void setup() {
  /* ... */
  containUvs(txtr, width, height);
}

void containUvs(PImage txtr, float w, float h) {
  float wc = txtr.width;
  float hc = txtr.height;  
  float sketchAspect = w / h;
  float invSketchAspect = 1.0 / sketchAspect;
  float txtrAspect = wc / hc;
  float invTxtrAspect = hc / wc;  
  float wf = sketchAspect * invTxtrAspect;
  float hf = invSketchAspect * txtrAspect;
  boolean txtrWide = wc > hc;
  boolean sketchWide = w > h;
  u = txtrWide ? sketchWide ?
    wf : 1.0 : sketchWide ? wf : 1.0;
  v = txtrWide ? sketchWide ?
    1.0 : hf : sketchWide ? 1.0 : hf;
}