VTK 学习----VTK对象绘制-3D坐标轴(vtkCubeAxesActor)

5.1 3D坐标轴(vtkCubeAxesActor)

5.1.1 对象接口说明

SetXAxisLabelVisibility(vtkTypeBool) SetYAxisLabelVisibility(vtkTypeBool) SetZAxisLabelVisibility(vtkTypeBool)	设置x、y、z轴刻度标签是否显示
SetXAxisTickVisibility(vtkTypeBool) SetYAxisTickVisibility(vtkTypeBool) SetZAxisTickVisibility(vtkTypeBool)	设置x、y、z轴刻度是否显示
SetXAxisMinorTickVisibility(vtkTypeBool) SetYAxisMinorTickVisibility(vtkTypeBool) SetZAxisMinorTickVisibility(vtkTypeBool)	设置x、y、z轴次刻度是否显示
SetDrawXGridlines(vtkTypeBool) SetDrawYGridlines(vtkTypeBool) SetDrawZGridlines(vtkTypeBool)	设置是否绘制x、y、z轴的网格线
SetDrawXInnerGridlines(vtkTypeBool) SetDrawYInnerGridlines(vtkTypeBool) SetDrawZInnerGridlines(vtkTypeBool)	设置是否绘制x、y、z轴的网格线的内部网格线
SetDrawXGridpolys(vtkTypeBool) SetDrawYGridpolys(vtkTypeBool) SetDrawZGridpolys(vtkTypeBool)	设置是否绘制x、y、z轴的网格线的内部网格面
SetLabelScaling(bool，int，int，int)	设置刻度标签的显示样式，假设坐标轴的值范围为0-200000，当参数1为false时，刻度标签按0-200000显示；参数1为true时，按0-200显示
SetXAxisRange(double,double) SetYAxisRange(double,double) SetZAxisRange(double,double)	设置x、y、z轴值的范围
SetScreenSize (double screenSize)	设置标题和标签文本的屏幕大小。默认值为10.0。
SetLabelOffset (double offset)	指定标签与轴之间的距离。默认值为20.0。
SetTitleOffset(double)	设置标题和刻度标签之间的距离。默认为20.0
SetCamera(vtkCamera *)	设置相机，以执行缩放。一般是将当前render的相机设置给坐标轴。
SetFlyMode(int)	指定一种模式来控制轴的绘制方式 enum FlyMode { VTK_FLY_OUTER_EDGES = 0,//外边缘 VTK_FLY_CLOSEST_TRIAD = 1,//最近位置 VTK_FLY_FURTHEST_TRIAD = 2,//最远位置 VTK_FLY_STATIC_TRIAD = 3,//静态最近位置，不随摄像头动而跳变位置。 VTK_FLY_STATIC_EDGES = 4 //静态所有外边缘位置，不随摄像头动而跳变位置。 };
SetXTitle (const char *) SetYTitle (const char *) SetZTitle (const char *)	设置x、y、z轴的标题
SetTickLocation	设置刻度线显示的位置 enum TickLocation { VTK_TICKS_INSIDE = 0,//内部 VTK_TICKS_OUTSIDE = 1,//外部 VTK_TICKS_BOTH = 2//两侧 };
SetInertia (int)	设置惯性因子，该惯性因子控制轴切换位置的频率（从一个轴跳到另一个轴），范围为1到VTK_INT_MAX。默认值是1
SetCornerOffset (double)	指定一个偏移量值，以便从轴连接的角“拉回”轴，以避免轴标签重叠。默认值是0
SetXAxisVisibility(vtkTypeBool) SetYAxisVisibility(vtkTypeBool) SetZAxisVisibility(vtkTypeBool)	设置x、y、z轴的显示状态。
SetGridLineLocation	指定网格线呈现的样式 enum GridVisibility { VTK_GRID_LINES_ALL = 0,//呈现所有网格线 VTK_GRID_LINES_CLOSEST = 1,//呈现最近的三个轴的网格线 VTK_GRID_LINES_FURTHEST =  2//呈现最远的三个轴的网格线 };

5.1.2 代码实现

void ESAxes::create()
{
	m_cubeAxesActor = vtkSmartPointer::New();
	m_cubeAxesActor->SetCamera(m_pRender->GetActiveCamera());
	//
	//轴的设置
	//设置x、y、z轴的起始和终止值
	m_cubeAxesActor->SetXAxisRange(0, 200000);
	m_cubeAxesActor->SetYAxisRange(0, 200000);
	m_cubeAxesActor->SetZAxisRange(0, 200000);
	//设置坐标轴线的宽度
	m_cubeAxesActor->GetXAxesLinesProperty()->SetLineWidth(0.5);
	m_cubeAxesActor->GetYAxesLinesProperty()->SetLineWidth(0.5);
	m_cubeAxesActor->GetZAxesLinesProperty()->SetLineWidth(0.5);
	//设置标题和标签文本的屏幕大小。默认值为10.0。
	m_cubeAxesActor->SetScreenSize(6);
	//指定标签与轴之间的距离。默认值为20.0。
	m_cubeAxesActor->SetLabelOffset(5);
	//显示坐标轴
	m_cubeAxesActor->SetVisibility(true);
	//指定一种模式来控制轴的绘制方式
	m_cubeAxesActor->SetFlyMode(0);
	//设置惯性因子，该惯性因子控制轴切换位置的频率（从一个轴跳到另一个轴）
	//m_cubeAxesActor->SetInertia(1);
	//
	//网格设置
	//开启x、y、z轴的网格线绘制
	m_cubeAxesActor->DrawXGridlinesOn();
	m_cubeAxesActor->DrawYGridlinesOn();
	m_cubeAxesActor->DrawZGridlinesOn();
	//设置x、y、z轴的内部网格线不绘制
	m_cubeAxesActor->SetDrawXInnerGridlines(false);
	m_cubeAxesActor->SetDrawYInnerGridlines(false);
	m_cubeAxesActor->SetDrawZInnerGridlines(false);
	//设置x、y、z轴网格线的颜色
	m_cubeAxesActor->GetXAxesGridlinesProperty()->SetColor(0.5, 0.5, 0.5);
	m_cubeAxesActor->GetYAxesGridlinesProperty()->SetColor(0.5, 0.5, 0.5);
	m_cubeAxesActor->GetZAxesGridlinesProperty()->SetColor(0.5, 0.5, 0.5);
	//指定网格线呈现的样式
	m_cubeAxesActor->SetGridLineLocation(2);
	//
	//刻度的设置
	//不显示x、y、z轴的次刻度
	m_cubeAxesActor->XAxisMinorTickVisibilityOff();
	m_cubeAxesActor->YAxisMinorTickVisibilityOff();
	m_cubeAxesActor->ZAxisMinorTickVisibilityOff();
	//设置刻度标签的显示方式(参数1为false，刻度标签按0-200000显示；为true时，按0-200显示)
	m_cubeAxesActor->SetLabelScaling(false, 0, 0, 0);
	//设置刻度线显示的位置(内部、外部、两侧)
	m_cubeAxesActor->SetTickLocation(1);
	//
	m_pRender->AddActor(m_cubeAxesActor);
	m_pRender->ResetCamera();
	m_pRender->ResetCameraClippingRange();
	m_pRenderWnd->Render();
}

5.1.3 扩展

5.1.3.1 显示问题-刻度与网格线分离

如下图：

较好的显示效果应该为：1处有网格线，2和3处有刻度标注。

出现该问题的原因：

（1）首先，vtkCubeAxesActor对象的构造函数中是分别为x、y、z三个方向都创建了4个vtkAxisActor对象，代码如下：

vtkCubeAxesActor::vtkCubeAxesActor() : vtkActor()
{
。。。
  for (int i = 0; i < NUMBER_OF_ALIGNED_AXIS; i++)
  {
    this->XAxes[i] = vtkAxisActor::New();
    this->XAxes[i]->SetTickVisibility(1);
    this->XAxes[i]->SetMinorTicksVisible(1);
    this->XAxes[i]->SetLabelVisibility(1);
    this->XAxes[i]->SetTitleVisibility(1);
    this->XAxes[i]->SetAxisTypeToX();
。。。

    this->YAxes[i] = vtkAxisActor::New();
    this->YAxes[i]->SetTickVisibility(1);
    this->YAxes[i]->SetMinorTicksVisible(1);
    this->YAxes[i]->SetLabelVisibility(1);
    this->YAxes[i]->SetTitleVisibility(1);
    this->YAxes[i]->SetAxisTypeToY();
    this->YAxes[i]->SetAxisPosition(i);
    this->YAxes[i]->SetAxisLinesProperty(this->YAxesLinesProperty);
    this->YAxes[i]->SetGridlinesProperty(this->YAxesGridlinesProperty);
    this->YAxes[i]->SetInnerGridlinesProperty(this->YAxesInnerGridlinesProperty);
。。。

    this->ZAxes[i] = vtkAxisActor::New();
    this->ZAxes[i]->SetTickVisibility(1);
    this->ZAxes[i]->SetMinorTicksVisible(1);
    this->ZAxes[i]->SetLabelVisibility(1);
    this->ZAxes[i]->SetTitleVisibility(1);
    this->ZAxes[i]->SetAxisTypeToZ();
   	。。。
。。。
。。。
}

NUMBER_OF_ALIGNED_AXIS = 4。

而针对指定网格线呈现的样式为VTK_GRID_LINES_FURTHEST时，x、y、z方向的都各只有一个vtkAxisActor会画网格线且不呈现刻度标注，代码如下：

void vtkCubeAxesActor::UpdateGridLineVisibility(int idx)
{
  if( this->GridLineLocation != VTK_GRID_LINES_ALL &&
      (this->DrawXGridlines || this->DrawYGridlines || this->DrawZGridlines) )
  {
    for(int i=0; i < NUMBER_OF_ALIGNED_AXIS; ++i)
    {
      this->XAxes[i]->SetDrawGridlines(0);
      this->YAxes[i]->SetDrawGridlines(0);
      this->ZAxes[i]->SetDrawGridlines(0);
      this->XAxes[i]->SetDrawGridlinesOnly(0);
      this->YAxes[i]->SetDrawGridlinesOnly(0);
      this->ZAxes[i]->SetDrawGridlinesOnly(0);
    }

	int xId = vtkCubeAxesActorTriads[idx][0];
	int yId = vtkCubeAxesActorTriads[idx][1];
	int zId = vtkCubeAxesActorTriads[idx][2];
	this->XAxes[xId]->SetDrawGridlines(this->DrawXGridlines);
	this->YAxes[yId]->SetDrawGridlines(this->DrawYGridlines);
	this->ZAxes[zId]->SetDrawGridlines(this->DrawZGridlines);

    // Update axis render list
    int id = 0;
    if(this->NumberOfAxesX == 1)
    {
      id = this->RenderAxesX[this->NumberOfAxesX] = vtkCubeAxesActorTriads[idx][0];
      this->XAxes[id]->SetDrawGridlinesOnly((this->RenderAxesX[0] != id) ? 1 : 0);
      this->NumberOfAxesX += (this->RenderAxesX[0] != id) ? 1 : 0;
    }
    if(this->NumberOfAxesY == 1)
    {
      id = this->RenderAxesY[this->NumberOfAxesY] = vtkCubeAxesActorTriads[idx][1];
      this->YAxes[id]->SetDrawGridlinesOnly((this->RenderAxesY[0] != id) ? 1 : 0);
      this->NumberOfAxesY += (this->RenderAxesY[0] != id) ? 1 : 0;
    }
    if(this->NumberOfAxesZ == 1)
    {
      id = this->RenderAxesZ[this->NumberOfAxesZ] = vtkCubeAxesActorTriads[idx][2];
      this->ZAxes[id]->SetDrawGridlinesOnly((this->RenderAxesZ[0] != id) ? 1 : 0);
      this->NumberOfAxesZ += (this->RenderAxesZ[0] != id) ? 1 : 0;
    }
  }
}

网格线是由图中箭头所指的vtkAxisActor对象绘制出来的，我们可以从vtkAxisActor绘制网格线的代码中看到：

void vtkAxisActor::BuildAxisGridLines(
double p1[3], double p2[3], double localCoordSys[3][3])
{
。。。
  // - Insert Gridlines points along the axis using the DeltaMajor vector
  double nbIterationAsDouble = (axisLength - axisShift) / vtkMath::Norm(deltaVector);
  int nbIteration = vtkMath::Floor(nbIterationAsDouble + 2 * FLT_EPSILON) + 1;
  nbIteration = (nbIteration < VTK_MAX_TICKS) ? nbIteration : VTK_MAX_TICKS;
  for (int nbTicks = 0; nbTicks < nbIteration; nbTicks++)
  {
    // Closest U
    this->GridlinePts->InsertNextPoint(gridPointClosest);
    this->GridlinePts->InsertNextPoint(gridPointU);
    // Farest U
    this->GridlinePts->InsertNextPoint(gridPointFarest);
    this->GridlinePts->InsertNextPoint(gridPointU);
    // Closest V
    this->GridlinePts->InsertNextPoint(gridPointClosest);
    this->GridlinePts->InsertNextPoint(gridPointV);
    // Farest V
    this->GridlinePts->InsertNextPoint(gridPointFarest);
    this->GridlinePts->InsertNextPoint(gridPointV);
    // PolyPoints
    this->GridpolyPts->InsertNextPoint(gridPointClosest);
    this->GridpolyPts->InsertNextPoint(gridPointU);
    this->GridpolyPts->InsertNextPoint(gridPointFarest);
this->GridpolyPts->InsertNextPoint(gridPointV);
。。。
}
。。。
}

5.1.3.2 显示问题-次刻度的网格没有绘制

次刻度的网格之所以没有绘制，是因为在vtkAxisActor绘制网格的接口中没有实现绘制次刻度网格。若想绘制次刻度网格线，必须自己修改源码实现绘制次网格线的代码，修改源码显示次网格线的效果如下：