setInstanceAttribute method

void setInstanceAttribute(int index, String name, Object value)

Sets one declared per-instance attribute on the instance at index.

name must name an attribute in the bound material's instance_attributes list, and value must match its declared type: a num for float, or the matching Vector2 / Vector3 / Vector4. An instance whose attributes are never set draws with zeros.

Implementation

void setInstanceAttribute(int index, String name, Object value) {
  RangeError.checkValidIndex(index, _instances, 'index');
  final schema = _requireSchema(name);
  final slot = schema.slot(name);
  if (slot == null) {
    throw ArgumentError('Unknown instance attribute "$name".');
  }
  final offset = index * schema.floatCount + slot.floatOffset;
  switch ((slot.type, value)) {
    case (FmatType.float_, final num v):
      _attributeData[offset] = v.toDouble();
    case (FmatType.vec2, final Vector2 v):
      _attributeData.setAll(offset, v.storage);
    case (FmatType.vec3, final Vector3 v):
      _attributeData.setAll(offset, v.storage);
    case (FmatType.vec4, final Vector4 v):
      _attributeData.setAll(offset, v.storage);
    default:
      throw ArgumentError(
        'Instance attribute "$name" is ${slot.type.glslType}; cannot assign '
        'a ${value.runtimeType}.',
      );
  }
  _revision++;
}