OpenGL de プログラミング

• glReadPixels()でピクセルを読み込んで表示する
• ピクセルデータをテクスチャに転送し、それを読み取って表示する

#include <iostream>
#include <GL/glut.h>
#include <cv.h>
#include <highgui.h>

//------------- プロトタイプ宣言 ------------------//
void display();
void reshape(int w, int h);
void myMouseFunc(int button,int state,int x,int y);
void myMouseMotion(int x,int y);
void keyboard(unsigned char key, int x, int y);

void DRAW_XYZ();
void DRAW_TRI();
void CopyToTexAndDisplay();
void ReadPixelsAndDisplay();

//----- テクスチャID -----//
GLuint texture[1];


//------------- 各種データ構造 ------------------------//
//マウスの状態
struct MOUSE
{
	int Xstart,Ystart;
	bool flag;
	double weight;
};
MOUSE MouseStatus={0,0,false,0.5};


//回転関係
struct ObjectRotate
{
	double xAngle,yAngle;
};
ObjectRotate ObjRot={0,0};

//------------- OpenGLの初期設定 -------------------------//
void GLUT_INIT()
{
	glutInitDisplayMode(GLUT_RGBA| GLUT_DOUBLE | GLUT_DEPTH);
	glutInitWindowSize(640,480);
	glutCreateWindow("Copy to Texture and ReadPixels");
}

void GLUT_CALL_FUNC()
{
	glutDisplayFunc(display);
	glutReshapeFunc(reshape);
	glutMouseFunc(myMouseFunc);
	glutMotionFunc(myMouseMotion);
	glutKeyboardFunc(keyboard);

}

void MY_INIT()
{
	glClearColor(1.0, 1.0, 1.0, 1.0);
	glEnable(GL_DEPTH_TEST);
	std::cout << "key [r]:glReadPixels\n"<<"key [t]:glCopyTexImage2D\n";
}

//----------- メイン関数 -----------------//
int main(int argc, char **argv)
{
	glutInit(&argc,argv);
	GLUT_INIT();
	
	GLUT_CALL_FUNC();
	MY_INIT();
	glutMainLoop();

	return 0;
}

//------------- ここから各種コールバック -----------------//
void display()
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

	glLoadIdentity();
	gluLookAt(3.0, 4.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);

	glRotated(ObjRot.xAngle,1,0,0);
	glRotated(ObjRot.yAngle,0,1,0);

	DRAW_XYZ();
	DRAW_TRI();

	glutSwapBuffers();

}

void reshape(int w, int h)
{
	glViewport(0, 0, w, h);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluPerspective(30.0, (double)w / (double)h, 1.0, 100.0);
	glMatrixMode(GL_MODELVIEW);
}

//------- マウス処理 --------//
void myMouseFunc(int button,int state,int x,int y)
{
	if(button == GLUT_LEFT_BUTTON &&state == GLUT_DOWN){
		MouseStatus.Xstart = x;
		MouseStatus.Ystart = y;
		MouseStatus.flag = true;
	}
	else{
		MouseStatus.flag =false;
	}

}

void myMouseMotion(int x,int y)
{
	if(MouseStatus.flag == false)return;

	static int xdir,ydir;

	xdir = x - MouseStatus.Xstart;
	ydir = y - MouseStatus.Ystart;

	ObjRot.xAngle += (double)ydir * MouseStatus.weight;
	ObjRot.yAngle += (double)xdir * MouseStatus.weight;

	MouseStatus.Xstart = x;
	MouseStatus.Ystart = y;
	
	glutPostRedisplay();
}


//-------- キーボード処理 ---------//
void keyboard(unsigned char key, int x, int y)
{
	switch(key)
	{
	case 't':
		CopyToTexAndDisplay();
		break;

	case 'r':
		ReadPixelsAndDisplay();
		break;

	case 'q':
	case 'Q':
	case '\033':
		exit(0);
		break;

	default:
		break;
	}
}


//------------ ここから各種関数 ---------------//
void DRAW_XYZ()
{
	glBegin(GL_LINES);

	glColor3d(0,1,0);//x
	glVertex2d(-100,0);
	glVertex2d(100, 0);

	glColor3d(1,0,0);//y
	glVertex2d(0,0);
	glVertex2d(0,100);

	glColor3d(0,0,1);//z
	glVertex3d(0,0,-100);
	glVertex3d(0,0, 100);
	glEnd();
}

void DRAW_TRI()
{
	glBegin(GL_TRIANGLES);
	glVertex2d(0,1);
	glVertex2d(-0.5, 0);
	glVertex2d(0.5, 0);
	glEnd();
}

void CopyToTexAndDisplay()
{
	std::pair<int,int> WindowSize(glutGet(GLUT_WINDOW_WIDTH),glutGet(GLUT_WINDOW_HEIGHT));
	IplImage *imgA = cvCreateImage(cvSize(WindowSize.first,WindowSize.second),IPL_DEPTH_8U,3);

	std::cout << "CopyToTexAndDisplay\n";
	glGenTextures(1, &texture[0]);
	glBindTexture(GL_TEXTURE_2D, texture[0]);
	glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR); //フィルタ
	glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
	//テクスチャ格納用メモリ確保
	glTexImage2D(GL_TEXTURE_2D,0,3, WindowSize.first,WindowSize.second,0, GL_RGB,GL_UNSIGNED_BYTE,NULL);
	
	glCopyTexImage2D( GL_TEXTURE_2D,0,GL_RGB,0,0,WindowSize.first,WindowSize.second,0);
	glGetTexImage(GL_TEXTURE_2D,0,GL_RGB,GL_UNSIGNED_BYTE,imgA->imageData);


	//OpenCVでの表示用に色、上下の調整
	cvFlip(imgA,imgA);
	cvCvtColor(imgA,imgA,CV_RGB2BGR);

	cvNamedWindow("CopyTexImage",CV_WINDOW_AUTOSIZE);
	cvShowImage("CopyTexImage",imgA);

	cvWaitKey(0); //wait処理

	glDeleteTextures(1,&texture[0]);

	cvReleaseImage(&imgA);//メモリ解放
	cvDestroyWindow("CopyTexImage"); //ウィンドウを破棄

}

void ReadPixelsAndDisplay()
{
	std::pair<int,int> WindowSize(glutGet(GLUT_WINDOW_WIDTH),glutGet(GLUT_WINDOW_HEIGHT));
	IplImage *imgA = cvCreateImage(cvSize(WindowSize.first,WindowSize.second),IPL_DEPTH_8U,3);

	std::cout << "ReadPixelsAndDisplay\n";
	glReadPixels(0,0,WindowSize.first,WindowSize.second,GL_RGB,GL_UNSIGNED_BYTE,imgA->imageData);

	cvFlip(imgA,imgA);
	cvCvtColor(imgA,imgA,CV_RGB2BGR);

	cvNamedWindow("ReadPixels",CV_WINDOW_AUTOSIZE);
	cvShowImage("ReadPixels",imgA);

	cvWaitKey(0); //wait処理

	cvReleaseImage(&imgA);//メモリ解放
	cvDestroyWindow("ReadPixels"); //ウィンドウを破棄
}