Fragment Shader Effects

 

Reading

Read Chapter 7.10.

Class startup

git checkout master
git pull
git checkout working
git merge master
Impatient? Git not being friendly today? 
git fetch origin
git checkout -b temp origin/master
You will not be able to push from the temp branch. You must add a symlink before running today's code. 
cd ~/cs40/code/w08-noise/
ln -s /usr/local/doc/textures/ data
Switch to your working branch, open qtcreator, and set your executable to nmap in w08-noise.
Initial Explorations
When you first run your program, you should get a texture mapped sphere. You can rotate using the x,y, and z keys. Use the v key to toggle shaders. The second shader is currently a per fragment lighting shader.
Perlin Noise
Ken Perlin's 1999 Talk
Clouds

We need random noise maps. Add srand(time(NULL)) to NoiseGenerator constructor.

Let's build a color gradient map. We'll need some helper functions in test_noise

Make a gradient image. Let yval vary from 0 to 1 as the rows change, and let the img(j,i)=vecColor(lerp(blue, white, yval)),

Now add some noise. To a first approximation, something like this could work: yval = yval + 0.15*surf1(x,y);. Note yval could exceed the range 0 to 1. If so, clamp it, don't wrap it