Nvidia Optix eye space intersection points

Question

How can I calculate eye space intersection coordinates in an OptiX program?

My research showed that only object and world coordinates are provided, but I cannot believe that there is no way to get the eye space coordinates.

Answer 1

It is possible to rotate the intersection point by the camera orientation like this:

__device__ void worldToEye(float3& pointInOut)
{
    const float3 Un = normalize(U);
    const float3 Vn = normalize(V);
    const float3 Wn = normalize(W);

    const float viewMat[3][3] = {{Un.x, Un.y, Un.z},
                                {Vn.x, Vn.y, Vn.z},
                                {Wn.x, Wn.y, Wn.z}};

    float point[3]  = {pointInOut.x, pointInOut.y, pointInOut.z};
    float result[3] = {0.0f, 0.0f, 0.0f};

    for (int i=0; i<3; ++i)
    {
        for (int j=0; j<3; ++j)
        {
            result[i] += viewMat[i][j] * point[j];
        }
    }

    pointInOut.x = result[0];
    pointInOut.z = result[1];
    pointInOut.y = result[2];
}

With the input point calculated:

float3 hit_point = t_hit * ray.direction;
worldToEye(hit_point);
prd.result = hit_point;