plotly.js
Version:
The open source javascript graphing library that powers plotly
118 lines (104 loc) • 4.43 kB
JavaScript
'use strict';
module.exports = function(arrays, asmoothing, bsmoothing) {
if(asmoothing && bsmoothing) {
return function(out, i0, j0, u, v) {
if(!out) out = [];
var f0, f1, f2, f3, ak, k;
// Since it's a grid of control points, the actual indices are * 3:
i0 *= 3;
j0 *= 3;
// Precompute some numbers:
var u2 = u * u;
var u3 = u2 * u;
var ou = 1 - u;
var ou2 = ou * ou;
var ou3 = ou2 * ou;
var v2 = v * v;
var ov = 1 - v;
var ov2 = ov * ov;
var ovv2 = ov * v * 2;
var a = -3 * ov2;
var b = 3 * (ov2 - ovv2);
var c = 3 * (ovv2 - v2);
var d = 3 * v2;
for(k = 0; k < arrays.length; k++) {
ak = arrays[k];
// Compute the derivatives in the v-direction:
f0 = a * ak[j0][i0] + b * ak[j0 + 1][i0] + c * ak[j0 + 2][i0] + d * ak[j0 + 3][i0];
f1 = a * ak[j0][i0 + 1] + b * ak[j0 + 1][i0 + 1] + c * ak[j0 + 2][i0 + 1] + d * ak[j0 + 3][i0 + 1];
f2 = a * ak[j0][i0 + 2] + b * ak[j0 + 1][i0 + 2] + c * ak[j0 + 2][i0 + 2] + d * ak[j0 + 3][i0 + 2];
f3 = a * ak[j0][i0 + 3] + b * ak[j0 + 1][i0 + 3] + c * ak[j0 + 2][i0 + 3] + d * ak[j0 + 3][i0 + 3];
// Now just interpolate in the v-direction since it's all separable:
out[k] = ou3 * f0 + 3 * (ou2 * u * f1 + ou * u2 * f2) + u3 * f3;
}
return out;
};
} else if(asmoothing) {
// Handle smooth in the a-direction but linear in the b-direction by performing four
// linear interpolations followed by one cubic interpolation of the result
return function(out, i0, j0, v, u) {
if(!out) out = [];
var f0, f1, f2, f3, k, ak;
i0 *= 3;
var u2 = u * u;
var u3 = u2 * u;
var ou = 1 - u;
var ou2 = ou * ou;
var ou3 = ou2 * ou;
for(k = 0; k < arrays.length; k++) {
ak = arrays[k];
f0 = ak[j0 + 1][i0] - ak[j0][i0];
f1 = ak[j0 + 1][i0 + 1] - ak[j0][i0 + 1];
f2 = ak[j0 + 1][i0 + 2] - ak[j0][i0 + 2];
f3 = ak[j0 + 1][i0 + 3] - ak[j0][i0 + 3];
out[k] = ou3 * f0 + 3 * (ou2 * u * f1 + ou * u2 * f2) + u3 * f3;
// mathematically equivalent:
// f0 = ou3 * ak[j0 ][i0] + 3 * (ou2 * u * ak[j0 ][i0 + 1] + ou * u2 * ak[j0 ][i0 + 2]) + u3 * ak[j0 ][i0 + 3];
// f1 = ou3 * ak[j0 + 1][i0] + 3 * (ou2 * u * ak[j0 + 1][i0 + 1] + ou * u2 * ak[j0 + 1][i0 + 2]) + u3 * ak[j0 + 1][i0 + 3];
// out[k] = f1 - f0;
}
return out;
};
} else if(bsmoothing) {
// Same as the above case, except reversed:
/* eslint-disable no-unused-vars */
return function(out, i0, j0, u, v) {
/* eslint-enable no-unused-vars */
if(!out) out = [];
var f0, f1, k, ak;
j0 *= 3;
var ou = 1 - u;
var v2 = v * v;
var ov = 1 - v;
var ov2 = ov * ov;
var ovv2 = ov * v * 2;
var a = -3 * ov2;
var b = 3 * (ov2 - ovv2);
var c = 3 * (ovv2 - v2);
var d = 3 * v2;
for(k = 0; k < arrays.length; k++) {
ak = arrays[k];
f0 = a * ak[j0][i0] + b * ak[j0 + 1][i0] + c * ak[j0 + 2][i0] + d * ak[j0 + 3][i0];
f1 = a * ak[j0][i0 + 1] + b * ak[j0 + 1][i0 + 1] + c * ak[j0 + 2][i0 + 1] + d * ak[j0 + 3][i0 + 1];
out[k] = ou * f0 + u * f1;
}
return out;
};
} else {
// Finally, both directions are linear:
/* eslint-disable no-unused-vars */
return function(out, i0, j0, v, u) {
/* eslint-enable no-unused-vars */
if(!out) out = [];
var f0, f1, k, ak;
var ov = 1 - v;
for(k = 0; k < arrays.length; k++) {
ak = arrays[k];
f0 = ak[j0 + 1][i0] - ak[j0][i0];
f1 = ak[j0 + 1][i0 + 1] - ak[j0][i0 + 1];
out[k] = ov * f0 + v * f1;
}
return out;
};
}
};