CS413: Refraction

Visualizing the difference between the Refraction angle and the View angle :

vec3f findRefracted(vec3f L, vec3f N, float n1, float n2)

{

vec3f R (0.f, 0.f, 0.f);

float LdN = L.dot(N);

float cos2 = 1 - (1 - pow(LdN,2))*pow((n1/n2),2);

cos2 = sqrt(cos2);

R = - (n1/n2) * (L - LdN * N) + cos2 * -N;

// what I had before....R = - N * LdN + (N * (-LdN) - L) * (n1/n2);

return R;

}

In VizShader :

vec3f unitvec = refractVec.dot(viewDir) ;

In the center, the refracted ray is going straight through ( same direction as the view dir) and the dot product between two parallel rays is 0 - so we get black. The differences are symmetric going out from the center.

Dec 13 2011

Breaking it Down - Visualizing the Components:

Tasks- Visualize the following:

View direction
Reflection direction
Normals
Refraction directions

hit 1
hit 2

Time between hits (distance)

Notes on Expectations :

View viz outer rim will match Reflection viz outer rim

(Grazing angle of reflection will match View almost identically)

Reflection will look like Normal directions compressed and shifted toward viewer
Refraction will be similar to View direction colors
When indices of refraction are equal, refraction directions and view directions will match.
Distance between hits will be greatest in center and diminish toward outer rim.

Ready, set, GO!

View Direction (Pointing away from Sphere)