blend method

void blend(Pose a, Pose b, double t)

This pose blended from a towards b by t (0 = a, 1 = b): translations and scales linearly, rotations along the shorter way.

Implementation

void blend(Pose a, Pose b, double t) {
  final u = 1 - t;
  for (var i = 0; i < translations.length; i++) {
    translations[i] = a.translations[i] * u + b.translations[i] * t;
    scales[i] = a.scales[i] * u + b.scales[i] * t;
  }
  for (var n = 0; n < nodeCount; n++) {
    final o = n * 4;
    final ra = a.rotations, rb = b.rotations;
    final dot =
        ra[o] * rb[o] +
        ra[o + 1] * rb[o + 1] +
        ra[o + 2] * rb[o + 2] +
        ra[o + 3] * rb[o + 3];
    final sign = dot < 0 ? -1.0 : 1.0;
    var x = ra[o] * u + rb[o] * t * sign;
    var y = ra[o + 1] * u + rb[o + 1] * t * sign;
    var z = ra[o + 2] * u + rb[o + 2] * t * sign;
    var w = ra[o + 3] * u + rb[o + 3] * t * sign;
    final length = math.sqrt(x * x + y * y + z * z + w * w);
    if (length > 1e-12) {
      x /= length;
      y /= length;
      z /= length;
      w /= length;
    }
    rotations[o] = x;
    rotations[o + 1] = y;
    rotations[o + 2] = z;
    rotations[o + 3] = w;
  }
}