可拖动坐标轴¶
一直想从头写一个vtkWidget来了解vtk。这两天晚上比较空，正好自己选一个交互实现下。
vtk官网有一个可以拖动轴的例子MovableAxes。可惜AxesActor继承自Prop3D而非Widget无法交互，并且例子只能绕相机方向旋转平移无法绕指定轴。就把这个例子改成vtkWidget好了。
自己实现效果
官网案例
仿照RoboDK交互方式，很多三维软件都是这种交互。印象中原来在贴吧看到过vtk实现这种交互，也许vtk有现成的，我这次找的时候没找到。
记录下实现vtkWidget和vtkWidgetRep遇到的问题。
1 素材¶
轴用ConeSource+LineSource，平面用PlaneSource，旋转自己实现一个Source（读stl），文字用VectorText。每个轴、平面、文字公用一个，原点单独设置。
2 Widget常用接口实现¶
需要在Rep中根据自己定义，实现这几个函数，以便vtk渲染时统一处理不同的Widget。
double *GetBounds() VTK_SIZEHINT(6) override;
void GetActors(vtkPropCollection *pc) override;
void ReleaseGraphicsResources(vtkWindow *) override;
int RenderOpaqueGeometry(vtkViewport *) override;
int RenderTranslucentPolygonalGeometry(vtkViewport *) override;
3 不同组件的选择¶
通过实现void RegisterPickers() override;让vtk判断捕捉那些actor。
// 捕捉
this->picker_ = vtkCellPicker::New();
this->picker_->SetTolerance(0.004); // 选择范围，window对角线百分比
for (int i = 0; i < 3; i++) {
this->picker_->AddPickList(this->axis_actors_[i]);
this->picker_->AddPickList(this->plane_actors_[i]);
this->picker_->AddPickList(this->rotate_actors_[i]);
}
this->picker_->PickFromListOn();
void MovableAxesRepresentation::SetLockPicker(vtkTypeBool lock)
{
if (lock == this->lock_camera_) {
return;
}
if (lock) {
for (int i = 0; i < 3; i++) {
this->picker_->DeletePickList(this->axis_actors_[i]);
this->picker_->DeletePickList(this->plane_actors_[i]);
this->picker_->DeletePickList(this->rotate_actors_[i]);
}
} else {
for (int i = 0; i < 3; i++) {
this->picker_->AddPickList(this->axis_actors_[i]);
this->picker_->AddPickList(this->plane_actors_[i]);
this->picker_->AddPickList(this->rotate_actors_[i]);
}
}
this->lock_camera_ = lock;
this->Modified();
}
void MovableAxesRepresentation::RegisterPickers()
{
vtkPickingManager *pm = this->GetPickingManager();
if (!pm) {
return;
}
pm->AddPicker(this->picker_, this);
}
4 Widget在屏幕上尺寸始终固定¶
vtkWidgetRepresentation提供了HandleSize和SizeHandlesInPixels用来确保Handle占固定像素，可以直接借助这个接口实现所有尺寸固定。
this->HandleSize = 5.0;
void MovableAxesRepresentation::SizeHandles()
{
double radius = this->vtkWidgetRepresentation::SizeHandlesInPixels(2, this->origian_sphere_->GetCenter());
for (int i = 0; i < 3; i++) {
this->axis_cones_[i]->SetHeight(3 * radius);
this->axis_cones_[i]->SetRadius(radius);
this->rotate_sources_[i]->SetRadius(radius);
this->label_actors_[i]->SetScale(radius * 3, radius * 3, radius * 3);
}
this->origian_sphere_->SetRadius(radius);
axis_offset_ = radius * 5 * default_axis_offset_;
plane_offset_ = radius * 5 * default_plane_offset_;
plane_wide_ = radius * 5 * default_plane_wide_;
rotate_offset_ = radius * 5 * default_rotate_offset_;
}
5 降低无效刷新¶
Rep下不调用this->Modified();不重新计算actor、source
void MovableAxesRepresentation::BuildRepresentation()
{
// 刷新Rep
if (!this->Renderer || !this->Renderer->GetRenderWindow()) {
return;
}
vtkInformation *info = this->GetPropertyKeys();
for (int i = 0; i < 3; i++) {
this->axis_actors_[i]->SetPropertyKeys(info);
this->plane_actors_[i]->SetPropertyKeys(info);
this->rotate_actors_[i]->SetPropertyKeys(info);
}
this->origian_actor_->SetPropertyKeys(info);
// actor、source重新计算
if (this->GetMTime() > this->BuildTime
|| this->Renderer->GetRenderWindow()->GetMTime() > this->BuildTime) {
...
}
// 重建和renderwindow更改时调整控制柄的大小
if (this->GetMTime() > this->BuildTime
|| this->Renderer->GetRenderWindow()->GetMTime() > this->BuildTime) {
this->SizeHandles();
this->BuildTime.Modified();
}
}
6 鼠标移入高亮，按下切换光标¶
Widget订阅事件、修改鼠标样式
this->CallbackMapper->SetCallbackMethod(vtkCommand::LeftButtonPressEvent, vtkWidgetEvent::Select,
this, MovableAxesWidget::SelectAction);
this->CallbackMapper->SetCallbackMethod(vtkCommand::LeftButtonReleaseEvent,
vtkWidgetEvent::EndSelect, this, MovableAxesWidget::EndSelectAction);
this->CallbackMapper->SetCallbackMethod(vtkCommand::MouseMoveEvent,
vtkWidgetEvent::Move, this, MovableAxesWidget::MoveAction);
int MovableAxesWidget::UpdateCursorShape(int state)
{
// 更新光标
if (this->ManagesCursor) {
switch (state) {
case MovableAxesRepresentation::MoveAxisX:
case MovableAxesRepresentation::MoveAxisY:
case MovableAxesRepresentation::MoveAxisZ:
case MovableAxesRepresentation::MovePlanX:
case MovableAxesRepresentation::MovePlanY:
case MovableAxesRepresentation::MovePlanZ:
case MovableAxesRepresentation::RotateAxisX:
case MovableAxesRepresentation::RotateAxisY:
case MovableAxesRepresentation::RotateAxisZ: {
return this->RequestCursorShape(VTK_CURSOR_SIZEALL);
}
default:
return this->RequestCursorShape(VTK_CURSOR_DEFAULT);
}
}
return 0;
}
Rep实现交互、actor样式切换
int ComputeInteractionState(int X, int Y, int modify = 0) override;
void StartWidgetInteraction(double eventPos[2]) override;
void WidgetInteraction(double newEventPos[2]) override;
void EndWidgetInteraction(double newEventPos[2]) override;
void MovableAxesRepresentation::HighlightNormal(const int &state)
{
// 根据交互状态，修改属性
for (int i = 0; i < 3; i++) {
this->axis_actors_[i]->SetProperty(this->property_[i]);
this->plane_actors_[i]->SetProperty(this->property_[i]);
this->rotate_actors_[i]->SetProperty(this->property_[i]);
}
switch (state) {
case MoveAxisX:
this->axis_actors_[0]->SetProperty(this->selected_property_[0]);
break;
case MoveAxisY:
this->axis_actors_[1]->SetProperty(this->selected_property_[1]);
break;
case MoveAxisZ:
this->axis_actors_[2]->SetProperty(this->selected_property_[2]);
break;
case MovePlanX:
this->plane_actors_[0]->SetProperty(this->selected_property_[0]);
break;
case MovePlanY:
this->plane_actors_[1]->SetProperty(this->selected_property_[1]);
break;
case MovePlanZ:
this->plane_actors_[2]->SetProperty(this->selected_property_[2]);
break;
case RotateAxisX:
this->rotate_actors_[0]->SetProperty(this->selected_property_[0]);
break;
case RotateAxisY:
this->rotate_actors_[1]->SetProperty(this->selected_property_[1]);
break;
case RotateAxisZ:
this->rotate_actors_[2]->SetProperty(this->selected_property_[2]);
break;
default:
break;
}
}
7 交互相关坐标计算¶
- 沿着轴平移
获取鼠标运动矢量，跟坐标轴点乘结果就是要平移距离
void MovableAxesRepresentation::MoveAxis(const int &state, double *p1, double *p2)
{
vtkNew<vtkTransform> posture_transform_;
posture_transform_->SetMatrix(posture_);
double v[3] { p2[0] - p1[0], p2[1] - p1[1], p2[2] - p1[2] };
double normal[3];
switch (state) {
case MoveAxisX: {
normal[0] = posture_->GetElement(0, 0);
normal[1] = posture_->GetElement(1, 0);
normal[2] = posture_->GetElement(2, 0);
auto distance = vtkMath::Dot(v, normal);
posture_transform_->Translate(distance, 0, 0);
} break;
case MoveAxisY: {
normal[0] = posture_->GetElement(0, 1);
normal[1] = posture_->GetElement(1, 1);
normal[2] = posture_->GetElement(2, 1);
auto distance = vtkMath::Dot(v, normal);
posture_transform_->Translate(0, distance, 0);
} break;
case MoveAxisZ: {
normal[0] = posture_->GetElement(0, 2);
normal[1] = posture_->GetElement(1, 2);
normal[2] = posture_->GetElement(2, 2);
auto distance = vtkMath::Dot(v, normal);
posture_transform_->Translate(0, 0, distance);
} break;
default:
return;
}
posture_transform_->Update();
posture_transform_->GetMatrix(posture_);
this->Modified();
this->BuildRepresentation();
}
- 在平面平移
获取鼠标运动矢量，求其在平面投影
void GetPlaneProjection(const double a[3], const double b[3], double c[3])
{
double squard = vtkMath::Dot(a, a);
double scale = vtkMath::Dot(b, a) / squard;
for (int i = 0; i < 3; i++) {
c[i] = b[i] - a[i] * scale;
}
}
void MovableAxesRepresentation::MovePlane(const int &state, double *p1, double *p2)
{
// 鼠标点移动到自身坐标系中
double pos_t1[4] { p1[0], p1[1], p1[2], 1 };
double pos_t2[4] { p2[0], p2[1], p2[2], 1 };
vtkNew<vtkMatrix4x4> posture_inv;
vtkMatrix4x4::Invert(posture_, posture_inv);
auto pos_t = posture_inv->MultiplyDoublePoint(pos_t1);
double v1[3] = { pos_t[0], pos_t[1], pos_t[2] };
pos_t = posture_inv->MultiplyDoublePoint(pos_t2);
double v2[3] = { pos_t[0], pos_t[1], pos_t[2] };
// 计算鼠标移动向量投影在对应平面
double v[3] { v2[0] - v1[0], v2[1] - v1[1], v2[2] - v1[2] };
double normal[3];
double projection[3];
switch (state) {
case MovePlanX: {
normal[0] = 1;
normal[1] = 0;
normal[2] = 0;
} break;
case MovePlanY: {
normal[0] = 0;
normal[1] = 1;
normal[2] = 0;
} break;
case MovePlanZ: {
normal[0] = 0;
normal[1] = 0;
normal[2] = 1;
} break;
default:
return;
}
// 平移
vtkNew<vtkTransform> posture_transform_;
posture_transform_->SetMatrix(posture_);
GetPlaneProjection(normal, v, projection);
posture_transform_->Translate(projection);
posture_transform_->Update();
posture_transform_->GetMatrix(posture_);
this->Modified();
this->BuildRepresentation();
}
- 沿着轴旋转
void MovableAxesRepresentation::RotateAxis(const int &state, double *p1, double *p2)
{
// 将鼠标位置移动到自身坐标系下，求两次鼠标位置向量在投影平面的夹角
vtkNew<vtkTransform> posture_transform;
posture_transform->SetMatrix(posture_);
if ((p1[0] - p2[0]) < 1e-4
&& (p1[1] - p2[1]) < 1e-4
&& (p1[2] - p2[2]) < 1e-4) {
return;
}
double pos_t1[4] { p1[0], p1[1], p1[2], 1 };
double pos_t2[4] { p2[0], p2[1], p2[2], 1 };
vtkNew<vtkMatrix4x4> posture_inv;
vtkMatrix4x4::Invert(posture_, posture_inv);
auto pos_t = posture_inv->MultiplyDoublePoint(pos_t1);
double v1[3] = { pos_t[0], pos_t[1], pos_t[2] };
pos_t = posture_inv->MultiplyDoublePoint(pos_t2);
double v2[3] = { pos_t[0], pos_t[1], pos_t[2] };
double normal[3];
switch (state) {
case RotateAxisX: {
normal[0] = 1;
normal[1] = 0;
normal[2] = 0;
} break;
case RotateAxisY: {
normal[0] = 0;
normal[1] = 1;
normal[2] = 0;
} break;
case RotateAxisZ: {
normal[0] = 0;
normal[1] = 0;
normal[2] = 1;
} break;
default:
return;
}
double projection1[3], projection2[3];
GetPlaneProjection(normal, v1, projection1);
GetPlaneProjection(normal, v2, projection2);
vtkMath::Normalize(projection1);
vtkMath::Normalize(projection2);
double axis[3];
vtkMath::Cross(projection1, projection2, axis);
double radians = acos(vtkMath::Dot(projection1, projection2));
double degrees = vtkMath::DegreesFromRadians(radians);
posture_transform->RotateWXYZ(degrees, axis);
posture_transform->Update();
posture_transform->GetMatrix(posture_);
this->Modified();
this->BuildRepresentation();
}