【VTK学习】空间几何变换

83 阅读 0 评论 55 点赞

我是靠谱客的博主等待音响，最近开发中收集的这篇文章主要介绍【VTK学习】空间几何变换，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

https://blog.csdn.net/minmindianzi/article/details/84279434

VTK相关的类有：

vtkTransform, vtkTransformFilter, vtkMatrix4x4等

相关的方法有：

• RotateX(angle)、RotateY(angle)、RotateZ(angle)

• RotateWXYZ(angle,x,y,z)

• Scale(x,y,z)

• Translate(x,y,z)

• SetMatrix(m)、GetMatrix(m)

• PostMultiply()、PreMultiply()

• SetPosition(x,y,z)、GetPosition(x,y,z)

• SetOrientation(x,y,z)、 GetOrientation(x,y,z)

• SetScale(sx,sy,sz)

• SetOrigin(x,y,z)、GetOrigin

空间变换类


vtkSmartPointer<vtkTransform> trans = vtkSmartPointer<vtkTransform>::New();

在VTK中，矩阵乘法默认是左乘（PreMultiply），在齐次矩阵符号中，M = M*A，其中M为当前变换矩阵，A为要应用矩阵（比如旋转矩阵或者平移矩阵）。

	trans->PreMultiply();//M=M*A

源码中是这样解释的： vtkTransform.h的156行

* Sets the internal state of the transform to PreMultiply. All subsequent
* operations will occur before those already represented in the
* current transformation. In homogeneous matrix notation, M = M*A where
* M is the current transformation matrix and A is the applied matrix.
* The default is PreMultiply.

A就是指“All subsequent operations”，M就是指“those already represented in the current transformation”

我对before的理解就是A左乘M（A的左边乘上M）

当然，也可以设置矩阵乘法为右乘（PostMultiply），在齐次矩阵符号中，M = A*M，其中M为当前变换矩阵，A为要应用矩阵（比如旋转矩阵或者平移矩阵）。

trans->PostMultiply();//M=A*M

源码中是这样写的：

* Sets the internal state of the transform to PostMultiply. All subsequent
* operations will occur after those already represented in the
* current transformation. In homogeneous matrix notation, M = A*M where
* M is the current transformation matrix and A is the applied matrix.
* The default is PreMultiply.

我对after的理解就是A右乘M（A的右边乘上M）

实例分析：

三维物体的初始齐次矩阵为：

矩阵右乘（post后置），先旋转再平移

trans->PostMultiply();//M=A*M
trans->RotateZ(30);
trans->Translate(1, 0, 0);

矩阵右乘（post后置），先平移再旋转

trans->PostMultiply();//M=A*M
trans->Translate(1, 0, 0);
trans->RotateZ(30);

矩阵左乘（pre前置），先旋转再平移

trans->PreMultiply();//M=M*A
trans->RotateZ(30);
trans->Translate(1, 0, 0);

矩阵左乘（pre前置），先平移再旋转

trans->PreMultiply();//M=M*A
trans->Translate(1, 0, 0);
trans->RotateZ(30);

#include <vtkLineSource.h>
#include <vtkPolyData.h>
#include <vtkSmartPointer.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkProperty.h>
#include <vtkAxesActor.h>
#include <vtkConeSource.h>
#include <vtkTextActor.h>
#include <vtkTextProperty.h>
#include <vtkTransform.h>
#include <vtkSphereSource.h>

#include "vtkAutoInit.h" 
VTK_MODULE_INIT(vtkRenderingOpenGL2); // VTK was built with vtkRenderingOpenGL2
VTK_MODULE_INIT(vtkInteractionStyle);
VTK_MODULE_INIT(vtkRenderingFreeType)

int main(int, char *[])
{
	vtkSmartPointer<vtkSphereSource> sphereSource =
		vtkSmartPointer<vtkSphereSource>::New();
	sphereSource->SetRadius(0.1);//设置半径
	sphereSource->Update();

	vtkSmartPointer<vtkPolyDataMapper> sphereMapper =
		vtkSmartPointer<vtkPolyDataMapper>::New();
	sphereMapper->SetInputConnection(sphereSource->GetOutputPort());

	vtkSmartPointer<vtkActor> sphereActor =
		vtkSmartPointer<vtkActor>::New();
	sphereActor->SetPosition(0, 0, 0);//设置演员的位置
	sphereActor->SetMapper(sphereMapper);//设置演员的映射器
	sphereActor->GetProperty()->SetColor(1, 0, 0);//设置演员的颜色

	vtkSmartPointer<vtkConeSource> coneSource =
		vtkSmartPointer<vtkConeSource>::New();
	coneSource->SetRadius(.2);
	coneSource->SetHeight(.5);
	coneSource->SetCenter(0, 0, 0);
	vtkSmartPointer<vtkPolyDataMapper> coneMapper =
		vtkSmartPointer<vtkPolyDataMapper>::New();
	coneMapper->SetInputConnection(coneSource->GetOutputPort());
	vtkSmartPointer<vtkActor> coneActor =
		vtkSmartPointer<vtkActor>::New();
	coneActor->SetMapper(coneMapper);

	vtkSmartPointer<vtkActor> oriConeActor =
		vtkSmartPointer<vtkActor>::New();
	oriConeActor->SetMapper(coneMapper);
#define AXIS_LEN 1.
	vtkSmartPointer<vtkAxesActor> oriAxesActor =
		vtkSmartPointer<vtkAxesActor>::New();
	oriAxesActor->SetPosition(0, 0, 0);
	oriAxesActor->SetTotalLength(AXIS_LEN, AXIS_LEN, AXIS_LEN);
	oriAxesActor->SetShaftType(0);
	oriAxesActor->SetAxisLabels(0);
	oriAxesActor->SetCylinderRadius(0.02);

	vtkSmartPointer<vtkAxesActor> axesActor =
		vtkSmartPointer<vtkAxesActor>::New();
	axesActor->SetPosition(0, 0, 0);
	axesActor->SetTotalLength(AXIS_LEN, AXIS_LEN, AXIS_LEN);
	axesActor->SetShaftType(0);
	axesActor->SetAxisLabels(0);
	axesActor->SetCylinderRadius(0.02);

	vtkSmartPointer<vtkTextActor> textActor =
		vtkSmartPointer<vtkTextActor>::New();
	textActor->SetPosition2(100, 40);
	textActor->GetTextProperty()->SetFontSize(24);
	textActor->GetTextProperty()->SetColor(1, 0, 0);


	vtkSmartPointer<vtkTransform> trans =
		vtkSmartPointer<vtkTransform>::New();

	//trans->PostMultiply();//M=A*M
	trans->PreMultiply();//M=M*A

	trans->RotateZ(30);
	//coneActor->SetPosition(1, 0, 0);永远M=M*A

	trans->Translate(1, 0, 0);
	//trans->RotateZ(30);
	//trans->Translate(1, 0, 0);
	//trans->RotateZ(30);


	coneActor->SetUserTransform(trans);
	textActor->SetInput("PostMultiply()nTranslate(1, 0, 0)nRotateZ(30)");


	cout << "GetMatrix:" << endl;
	if (coneActor->GetMatrix() != NULL)
	{
		coneActor->GetMatrix()->Print(cout);
	}
	else
	{
		cout << "NULL" << endl;
	}
	cout << "GetUserMatrix:" << endl;
	if (coneActor->GetUserMatrix() != NULL)
	{
		coneActor->GetUserMatrix()->Print(cout);
	}
	else
	{
		cout << "NULL" << endl;
	}

	vtkSmartPointer<vtkRenderer> renderer1 =
		vtkSmartPointer<vtkRenderer>::New();
	vtkSmartPointer<vtkRenderer> renderer2 =
		vtkSmartPointer<vtkRenderer>::New();

	vtkSmartPointer<vtkRenderWindow> renderWindow =
		vtkSmartPointer<vtkRenderWindow>::New();
	renderWindow->SetSize(800, 400);
	renderWindow->AddRenderer(renderer1);
	renderWindow->AddRenderer(renderer2);
	vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
		vtkSmartPointer<vtkRenderWindowInteractor>::New();
	renderWindowInteractor->SetRenderWindow(renderWindow);

	double leftViewport[] = { 0.0, 0.0, 0.5, 1.0 };
	double rightViewport[] = { 0.5, 0.0, 1.0, 1.0 };

	renderer1->AddActor(oriAxesActor);
	renderer1->AddActor(sphereActor);
	renderer1->AddActor(oriConeActor);
	renderer2->AddActor(axesActor);
	renderer2->AddActor(sphereActor);
	renderer2->AddActor(coneActor);
	renderer2->AddActor2D(textActor);
	renderer1->SetBackground(.3, .3, .5);
	renderer2->SetBackground(.2, .4, .5);
	renderer1->SetViewport(leftViewport);
	renderer2->SetViewport(rightViewport);

	renderWindow->Render();
	renderWindowInteractor->Start();

	return EXIT_SUCCESS;
}