学步园

SoEventCallback是Open Inventor用来管理事件的，SoKeyboardEvent是键盘事件，SO_KEY_PRESS_EVENT宏可以获得是键盘上哪个键被操作了，SoSwitch是一个节点切换开关节点，这里用来管理颜色信息。

代码如下

// 预定义COIN宏  
#define COIN_DLL  
#define SOWIN_DLL  
// 加载COIN库文件  
#ifdef _DEBUG  
#pragma comment(lib, "SoWin1d.lib")  
#pragma comment(lib, "Coin3d.lib")  
#else  
#pragma comment(lib, "SoWin1.lib")  
#pragma comment(lib, "Coin3.lib")  
#endif  
// 添加COIN头文件-Window操作显示库和节点库  

#include <Inventor/Win/SoWin.h>
#include <Inventor/Win/viewers/SoWinExaminerViewer.h>
#include <Inventor/events/SoKeyboardEvent.h>
#include <Inventor/nodes/SoCube.h>
#include <Inventor/nodes/SoDirectionalLight.h>
#include <Inventor/nodes/SoEventCallback.h>
#include <Inventor/nodes/SoMaterial.h>
#include <Inventor/nodes/SoPerspectiveCamera.h>
#include <Inventor/nodes/SoTransform.h>
#include <Inventor/nodes/SoSeparator.h>
#include <Inventor/nodes/SoSwitch.h>


void changeColor(const char* color)
{
	SoSeparator *r;
	SoNode *n;
	SoSwitch *s;
	if (!(r = (SoSeparator *)SoNode::getByName(color))) 
	{
		fprintf(stderr, "Error: Couldn't find separator for %s light.\n",	color);
		return;
	}
	n = r->getChild(0);
	if (n->getTypeId() == SoSwitch::getClassTypeId())
	{
		s = (SoSwitch*) n;
	}
	else
	{
		fprintf(stderr, "Error: SoSwitch node expected.\n");
		return;
	}
	s->whichChild.setValue(s->whichChild.getValue() ? 0 : 1);
	return;
}

void keyCB(void *userData, SoEventCallback *eventCB) 
{
	const SoEvent *event = eventCB->getEvent();
	if (SO_KEY_PRESS_EVENT(event, R))
	{
		changeColor("red");
		eventCB->setHandled(); 
	}
	if (SO_KEY_PRESS_EVENT(event, Y))
	{
		changeColor("yellow");
		eventCB->setHandled(); 
	}
	if (SO_KEY_PRESS_EVENT(event, G))
	{
		changeColor("green");
		eventCB->setHandled(); 
	}
}


SoSeparator *readSGFromFile (const char* filename)
{
	SoInput in;
	if (!in.openFile(filename))
	{
		fprintf(stderr, "Could not open file %s\n", filename);
		return NULL;
	}
	SoSeparator *sg = SoDB::readAll(&in);
	if (!sg) 
	{
		fprintf(stderr, "Error reading file. \n");
		return NULL;
	}
	in.closeFile();
	return sg;
}

int main (int argc, char** argv)
{
	HWND win = SoWin::init(argv[0]);
	if (win == NULL) exit(1);
	SoSeparator* root = new SoSeparator;
	root->ref();
	SoEventCallback *e = new SoEventCallback;
	e->addEventCallback(SoKeyboardEvent::getClassTypeId(), keyCB, root);
	root->addChild(e);
	root->addChild(readSGFromFile("trafficlight.iv"));
	SoWinExaminerViewer* x = new SoWinExaminerViewer(win);
	x->setSceneGraph(root);
	x->setViewing(FALSE);
	x->setTitle("traffic light example");
	x->show(); 
	SoWin::show(win);
	SoWin::mainLoop();
	return 0;
}

iv文件如下

#Inventor V2.1 ascii

Separator {
  DEF red Separator {
    Switch {
      whichChild 0
      Material {
        diffuseColor 1 0 0
      }
      Material {
        diffuseColor 0.3 0.3 0.3
      }
    }
    DEF s Sphere {
      radius 0.12
    }
  }

  DEF yellow Separator {
    Switch {
      whichChild 1
      Material {
        diffuseColor 1 1 0
      }
      Material {
        diffuseColor 0.3 0.3 0.3
      }
    }
    Transform {
      translation 0 -0.25 0
    }
    USE s
  }

  DEF green Separator {
    Switch {
      whichChild 1
      Material {
        diffuseColor 0 1 0
      }
      Material {
        diffuseColor 0.3 0.3 0.3
      }
    }
    Transform {
      translation 0 -0.5 0
    }
    USE s
  }

  Transform {
    translation 0 -0.25 -0.1 
  }
  Material {
    diffuseColor 0.2 0.2 0.2
  }
  Cube {
    width 0.3
    height 0.8
    depth 0.3
  }
}

运行结果如下