images stucked because of glLoadMatrixd

OpenGL OpenGL: Basic Coding
1

Hi there!!

I’ve been working with OpenCV to capture images from a webcam and using its functions to proccess this images. I needed to detect a marker for which I used ARToolKit. Now, I need to draw a kind of blackboard according to the marker, for which I still need ARToolkit plus OpenGL for perspective transformation and so on.

I’ve already managed to use my captured frame as the background in an OpenGL window. I didn’t use GLUT, as GLUT has its own mainloop, so I used freeGLUT instead. What I am trying to do now is to draw on the background my “blackboard”.

This is the code I use to have the openCV image as background and works:

Initializing function:

int init(void)
{
//general initialization:
	char cadena[25]="GestionMarcaAR\0";
	char **argv;
	int argc = 1;

	argv=(char **)malloc(sizeof(char *));
	*argv=(char *)malloc(sizeof(char)*10);
	strcpy(*argv, cadena);

	glutInit(&argc,argv); //we cheat it ;P

	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
	glutInitWindowPosition(800, 400);
	glutInitWindowSize(320,240);
	glutCreateWindow("Name");

	glutDisplayFunc(draw);
	glutIdleFunc(draw);

//initializating the texture mapping
	GLuint mTexture;
	glGenTextures(1, &mTexture);
	glBindTexture(GL_TEXTURE_2D, mTexture);
	glEnable(GL_TEXTURE_2D);
	glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);	
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);

	
	glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);

	glClearColor(1.0f, 1.0f, 1.0f, 1.0f); //color blanco de fondo
	glColor3f(0.0f,0.0f,0.0f);

	return 0;
}

Drawing function:

void draw()
{
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB,320,240,0,GL_BGR,GL_UNSIGNED_BYTE, imagen->imageData);
	
	glBegin(GL_POLYGON);
		glTexCoord2f(0.0f, 0.0f); glVertex2f(-1.0f, -1.0f);
		glTexCoord2f(1.0f, 0.0f); glVertex2f( 1.0f, -1.0f);
		glTexCoord2f(1.0f, 1.0f); glVertex2f( 1.0f,  1.0f);
		glTexCoord2f(0.0f, 1.0f); glVertex2f(-1.0f,  1.0f);
	glEnd();
	
	glFlush();
	
	glutSwapBuffers();
}

And what is needed to be anywhere in the mainloop of openCV:

glutPostRedisplay();  //to force "draw" function to be called
glutMainLoopEvent();   //freeglut function

Ok, fine. Now I try to add this code snippet which works propperly in the simple program, but doesn’t in my draw function:

double    gl_para[16];
	
argDrawMode3D();
glClearDepth(1.0);
glClear(GL_DEPTH_BUFFER_BIT);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);

argConvGlpara(patt_trans,gl_para);
glMatrixMode(GL_MODELVIEW);
glLoadMatrixd(gl_para);

glTranslatef(-270.0,0.0,0.0);

glEnable (GL_POLYGON_STIPPLE);
	glPolygonStipple (eight);
	glRectf (125.0, 25.0, 225.0, 125.0);
glDisable (GL_POLYGON_STIPPLE);


glFlush();
glDisable(GL_DEPTH_TEST);
glutSwapBuffers();

The problem is that my image gets stucked and doesn’t change and it’s because of “glLoadMatrixd(gl_para)”. Does anyone knows why is this happening?? Any ideas??

Thanks in advance :smiley: