bspline2glsl.py

def N_i_k(k):
    if k == 1:
        return "float N_i_"+str(k)+"(in float t, in float i) { return step(i,t) * step(t,i+1.); }"
    else:
        return "float N_i_"+str(k)+"(in float t, in float i) { return (t - i)/"+str(k-1)+".*N_i_"+str(k-1)+"(t, i) + (i + "+str(k)+".0 - t)/"+str(k-1)+".0*N_i_"+str(k-1)+"(t, i + 1.); }"

def bspline(order, num_count_points):
    code = ""
    for n in range(0,order):
        code += N_i_k(n+1) + "\n"

    code += "vec3 P_i("
    for n in range(1,num_count_points+1):
        code += "vec3 p" + str(n) + ", "
    code += "float t)\n"

    code += "{\n"
    code += "  vec3 p = vec3(0.);\n"
    for n in range(1,num_count_points+1):
        code += "  p += N_i_" + str(order)+ "(t, "+str(n)+".)*p"+str(n)+";\n"
    code += "  return p;\n"
    code += "}\n"
    return code

if __name__ == "__main__":
    print(bspline(8, 2))