How to set up (create) sliced cylinder in OpenGL - opengl

Question

How would you create a cylinder such as this?
http://www.eicac.co.uk/Images/SLICED-CYLINDER.png
I am guessing gluCylinder is not an option?

Answer 1

create it with one ribbon and two fans
Lets assume that point [0, 0, 0] is at the center of the shape's base and Z-axis is up. Using constants from the Image.
bottom cap
A simple disc.
glBegin(GL_TRIANGLE_FAN)
glVertex3d(0.0, 0.0, 0.0) // center
for angle from 0 to π (whatever step)
double x = 0.5 * D * cos(angle);
double y = 0.5 * D * sin(angle);
glVertex3d(x, y, 0.0);
glEnd();
side wall
We need to calculate the actual slope function.
It will be of the form y = a * x + b and have points (0.0, H) and (0.5*D, H2).
Thus we have to solve for a and b. We have b = H and a = (H2 - H) / 0.5 * D
double a = (H2 - H) / 0.5 * D;
double b = H;
glBegin(GL_TRIANGLE_STRIP)
for angle from 0 to π (whatever step)
double x = 0.5 * D * cos(angle);
double y = 0.5 * D * sin(angle);
double height = a * x + b;
glVertex3d(x, y, 0.0);
glVertex3d(x, y, height);
glEnd();
top cap
We combine the previous steps and seal the top.
double a = (H2 - H) / 0.5 * D;
double b = H;
glBegin(GL_TRIANGLE_FAN)
glVertex3d(0.0, 0.0, H) // center
for angle from 0 to π (whatever step)
double x = 0.5 * D * cos(angle);
double y = 0.5 * D * sin(angle);
double height = a * x + b;
glVertex3d(x, y, height);
glEnd();