What's wrong with my texture mapping?

I use texture mapping to do distortion effect of my program. However, the effect seems not uniform. What are the correct flags I need to set?
original: [http://www.cs.ust.hk/~yvonne/gl/e1.jpg"]
distorted: [http://www.cs.ust.hk/~yvonne/gl/e2.jpg"]

Originally posted by ribbery:
I use texture mapping to do distortion effect of my program. However, the effect seems not uniform. What are the correct flags I need to set?
original: [“http://www.cs.ust.hk/~yvonne/gl/e1.jpg”]
distorted: [“http://www.cs.ust.hk/~yvonne/gl/e2.jpg”]