getMatrix4 method

Implementation

Matrix4? getMatrix4(Map? spec) {
  if (spec == null || spec.isEmpty) {
    return null;
  }

  final type = spec["_type"] ?? "default";
  switch (type) {
    case "scale":
      return Matrix4.diagonal3Values(
          parseDouble(spec["scaleX"], defaultValue: 1),
          parseDouble(spec["scaleY"], defaultValue: 1),
          1.0);
    case "translate":
      final offset = getOffset(spec["offset"]) ?? Offset.zero;
      return Matrix4.translationValues(offset.dx, offset.dy, 0.0);
    case "rotate":
      createZRotation(sin, cos) {
        final Matrix4 result = Matrix4.zero();
        result.storage[0] = cos;
        result.storage[1] = sin;
        result.storage[4] = -sin;
        result.storage[5] = cos;
        result.storage[10] = 1.0;
        result.storage[15] = 1.0;
        return result;
      }
      computeRotation(radians) {
        if (radians == 0.0) {
          return Matrix4.identity();
        }
        final double sin = math.sin(radians);
        if (sin == 1.0) {
          return createZRotation(1.0, 0.0);
        }
        if (sin == -1.0) {
          return createZRotation(-1.0, 0.0);
        }
        final double cos = math.cos(radians);
        if (cos == -1.0) {
          return createZRotation(0.0, -1.0);
        }
        return createZRotation(sin, cos);
      }
      return computeRotation(parseDouble(spec["angle"]) * math.pi / 180);
    case "flip":
      return Matrix4.diagonal3Values(parseBool(spec["flipX"]) ? -1.0 : 1.0,
          parseBool(spec["flipY"]) ? -1.0 : 1.0, 1.0);
    default:
      return null;
  }
}