readme_hw3.txt

## Shading

### 3.1 Phong Shading

For the Phong Shading implementation we started by transforming the normals to camera space.
Compute the light direction and the view direction.
Then using our previous modifications we compute the color according to the formula: 
I = k_a*L_a + k_d*(n*l)*L_d + k_s*(r*v)^@ *L_s


### 3.2 Toon Shading

For this second par, we implemented Toon Shading by storing a discrete range of colors in
a 1D texture (allready given to us) and mapping n*l and r*v to it. We first bound the shader
to the texture, then compute ambient term, diffuse term and specular term using the texture
sampler tex to define the color of the shader.


### 3.3 artistic Shading

In this part, we do not use the Phong reflection model, but use a 2D "gradient" parametered by the dot product
between the the normal of the position and the lighting position, and the reflection of the lighting and the eye. 


### 3.4 Flat Shading

The vectors are calculated in the exact same way as in the practical.
To compute the normal vectors using dFdx and dFdy, one must know that these 
functions return the variation of the given parameterbetween two adjacent pixels
(hence the x and y). Thus, these funtions are useful to compute the gradient in the
two direction. The normal vector is derived by taking the cross product.



### 3.5 Spot Light Shading

Here we have to compute the spot effect with the given formula. Then we compute the cos of the
angle between light_dir and spot_dir (the two vector are normalized) if the angle is upper than
the spot_cos_cutoff (i.e. the angle is smaller) we apply the formula on the other case we just 
let the ambiant light.