Basic OpenGL Drawing Examples

o Drawing a Graph

typedef GLint point[2];
point graph[5] = {{50,100},{150,150},{250,105},
                            {350,55},{450,50}};

glBegin (GL_LINE_STRIP);
	for (j = 0 ; j < 5 ; j++) glVertex2iv (graph[j]);
glEnd ();



o A Box Function

void Box (GLint xcenter, GLint ycenter, GLint size) {
	glBegin (GL_LINE_STRIP);
		glVertex2i (xcenter - size, ycenter + size);
		glVertex2i (xcenter + size, ycenter + size);
		glVertex2i (xcenter + size, ycenter - size);
		glVertex2i (xcenter - size, ycenter - size);
		glVertex2i (xcenter - size, ycenter + size);
	glEnd ();
	}



o Marking the Graph Vertices with the Box Function

for (j = 0 ; j < 5 ; j++) Box (graph[j][0], graph[j][1], 2);



o Marking the Graph Vertices Directly with the Rect Function

for (j = 0 ; j < 5 ; j++)
	glRecti (graph[j][0] - 2, graph[j][1] + 2,
	         graph[j][0] + 2, graph[j][1] - 2);