I have been working on refractions too. I have been using opengl 3.3 and I tried to compute the refracted ray using the glm library (glm::refract). I’m trying to make my model partly transparent.

For generating the refracted ray:

Ray Compute_refraction(int hitId, float t)
{
const float airIndex = 1.0003f;
const float glassIndex = 1.5000f;
const float refractiveIndex = airIndex/glassIndex;
Ray refracted;
glm::vec3 v1 = T[hitId].p2 – T[hitId].p1;
glm::vec3 v2 = T[hitId].p3 – T[hitId].p1;
glm::vec3 tri_norm = -glm::normalize(glm::cross(v1,v2));
glm::vec3 PI = ray_r.ray_o + t*ray_r.ray_d;
refracted.ray_o = PI;
refracted.ray_d = glm::normalize(glm::refract(ray_r.ray_d,tri_norm,refractiveIndex));
refracted.tMin = 0.0f;
refracted.tMax = 1000000.0f;

return refracted;
}

where ray is:

struct Ray{

glm::vec3 ray_o;
glm::vec3 ray_d;
float tMin;
float tMax;
}ray_r;

// create a Triangle
typedef struct
{
glm::vec3 p1;
glm::vec3 p2;
glm::vec3 p3;
glm::vec2 texCoord1;
glm::vec2 texCoord2;
glm::vec2 texCoord3;
unsigned int matIndex1;

}triangle;
vector T;

I’m trying to compute the transparency when the rays intersect with the model. Can you help me with it

thanks
Cintya

and do the texture coordinate generation in the GLSL shader instead. If you can do that I’d appreicate it since its my understanding that openGL 3 does not support texture generation thru fixed pipeline anymore or does it? In that case it needs to be done in the shader. I’d appreciate if you explained more about this in tutorial or even responding here would be fine!