what's lacking for non-Escher-like appearance?

OpenGL OpenGL: Basic Coding
1

I get this:
http://img207.imageshack.us/my.php?image=picture9uz1.png

my “prepare” function looks like this:


	double t; int i;
	double dt = (2*M_PI)/numberOfColorStrips;
	
	vertexArray = calloc(4*numberOfColorStrips, 3*sizeof(double));
	normalArray = calloc(4*numberOfColorStrips, 3*sizeof(double));
	colorArray = calloc(4*numberOfColorStrips, 3*sizeof(double));
	
	first = calloc(numberOfColorStrips, sizeof(int));
	count = calloc(numberOfColorStrips, sizeof(int));
	
	for ( i=0; i<numberOfColorStrips; i++ ){
		count[i] = 4;
	}
	
	BOOL up = YES;
	
	for ( t = 0, i=0; t <= 2*M_PI; t += dt, i+=6) {
		if ( up ){
			vertexArray[i] = sin(t);
			vertexArray[i+1] = -h;
			vertexArray[i+2] = cos(t);
			
			vertexArray[i+3] = sin(t);
			vertexArray[i+4] = +h;
			vertexArray[i+5] = cos(t);
			
			up = NO;
			
		} else {
			vertexArray[i] = sin(t);
			vertexArray[i+1] = +h;
			vertexArray[i+2] = cos(t);
			
			vertexArray[i+3] = sin(t);
			vertexArray[i+4] = -h;
			vertexArray[i+5] = cos(t);
			
			up = YES;
			
		}
		
		
		colorArray[i  ] = colorArray[i+3] = (random()%256)/256.0;
		colorArray[i+1] = colorArray[i+4] =  (random()%256)/256.0;
		colorArray[i+2] = colorArray[i+5] =  (random()%256)/256.0;

		
		double d1[3], d2[3];
		d1[0] = vertexArray[i] -  vertexArray[i+3];
		d1[1] = vertexArray[i+1] - vertexArray[i+4];
		d1[2] = vertexArray[i+2] - vertexArray[i+5];

		d2[0] = vertexArray[i] -  vertexArray[i-3];
		d2[1] = vertexArray[i+1] - vertexArray[i-2];
		d2[2] = vertexArray[i+2] - vertexArray[i-1];
		
		normcrossprod(d1, d2, &normalArray[i]);
		normcrossprod(d1, d2, &normalArray[i+3]);
		
		
		
		first[i/6] = (i/6)*2;

	}

my drawRect functions looks like this:


	glClearColor(0.2, 0.2, 0.2, 0.0);
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
	
	glEnableClientState(GL_VERTEX_ARRAY);
	glEnableClientState(GL_COLOR_ARRAY);
	glEnableClientState(GL_NORMAL_ARRAY);

//	glEnableClientState(GL_INDEX_ARRAY);

	
	glVertexPointer(3, GL_DOUBLE, 0, vertexArray);
	glColorPointer(3, GL_DOUBLE, 0, colorArray);
	glNormalPointer(GL_DOUBLE, 0, normalArray);
//	glIndexPointer(GL_INT, 0, indexArray);
	
	gluLookAt(-4.5, 4.0, -3.0,
			   0.0, 0.0, 0.0,
			  -2.0, 1.0, 0.0);
	
	
//	glDrawArrays(GL_QUAD_STRIP, 0, 2*numberOfColorStrips);

	glMultiDrawArrays(GL_QUADS, first, count, numberOfColorStrips);
	
	
	glFlush();

Thanks a lot, I’m stuck at this.

2

glDepthMask(GL_TRUE);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);

3

thanks a lot!