// rsmp2d
//
// demos 2D convolution

string dataFile = "../data/pix1-11.nrrd";
int dataSize = 11;
int imgSize = 200;
image(2)[] img = load (dataFile);
field#2(2)[] F = img ⊛ bspln3;

strand sample (int ui, int vi)
{
    real uu = real(dataSize)*(real(ui)+0.5)/real(imgSize) - 0.5;
    real vv = real(dataSize)*(real(vi)+0.5)/real(imgSize) - 0.5;
    vec2 pos = [uu,vv];
    //output real val = -∞;
    output vec3 vxy = [0.0,0.0,0.0];

    update
    {
        if (inside(pos,F)) {
          real f = F@pos;
          vec2 grad = ∇F@pos;
          // HEY (BUG) what happened to vector indexing?
          vxy = [0.1 if f > 0.01 else 0.0, grad[0], grad[1]];
          //vxy = [0.1 if f > 0.01 else 0.0, dot(grad, [1.0,0.0]), dot(grad, [0.0,1.0])];
        }
        stabilize;
    }
}

initially [ sample(ui, vi) | vi in 0..(imgSize-1), ui in 0..(imgSize-1) ];