Hi, I'm trying to draw a cylinder from scratch. I can't seem to find anywhere on the net that will tell me howto do this. Can anybody point me to a good tutorial on howto build cylinders and other round objects from scratch?? Thanks!

you can pretty much do whatever you want w/ parametric equations.

I don't know can I help you with this code. If yes, I'll be glad.

The routine below allow you to build straight and bend cylinders from scratch. The cylinder build it along the Y axis. So its bottoms lay on the x-Z plane. It is similar to gluCylinder() func.

To use the routine you must set several parameters:
TopRadius, BottomRadius - the radiuses of cylinder bottoms
U - the number of slices
V - the number of vertical segments (not stacks!)
Bend - the bend angel
Hgt - the height of the cylinder

The code is not clear and there is a trouble with different bottoms, but the additional functionality (bending) are very useful.
In you draw function call glCallList(1) to draw a cylinder.

procedure TForm1.Eval;
var
BendAng, SegHgt, SegBend, Ang, R, X, Y, Z: Single;
CenterTop: TGLArrayf3;
mR, RR, cang: Single;
I, J: Integer;
begin
// The cylinder builds along Y axis. The bottoms are placed in the X-Z plane

// Radius from center of bottom circle to the imaginary line of bending
RR := Hgt / (Bend * PI / 180);
SegHgt := Hgt / V; // The segment height
SegBend := Bend / V; // The segment bend angle
BendAng := 360 / U; // The bottoms angle

for I := 0 to U - 1 do begin
Ang := DegToRad(I * BendAng); // Angle
for J := 0 to V do begin
R := TopRadius + (BottomRadius - TopRadius) * J;

// Z coord of the circle
Z := R * Sin(Ang); // Z = const

if Bend = 0 then begin
// when no bending
X := R * Cos(Ang);
Y := J * SegHgt;
end
else begin
// when bending present
cang := DegToRad(J * SegBend); // Bend angle for current segment
{ Radius from the point to the imaginary line of bending including
rotation around Y axis (X coord of the circle) }
mR := RR - R * Cos(Ang);
// Rotate point along imaginary line
X := mR * Cos(cang) - RR;
Y := mR * Sin(cang);
end;

// Stores in array
A[I, J, 0] := X;
A[I, J, 1] := Y;
A[I, J, 2] := Z;
end;
end;

// Find tops center
if Bend = 0 then begin
// when no bending
CenterTop[0] := 0.0;
CenterTop[1] := Hgt;
end
else begin
// when bending present
cang := DegToRad(V * SegBend); // Bend angle for top segment
CenterTop[0] := RR * Cos(cang) - RR;
CenterTop[1] := RR * Sin(cang);
end;
CenterTop[2] := 0.0;

// Draws a cylinder

glNewList(1, GL_COMPILE);

// Bottom circle
glBegin(GL_TRIANGLE_FAN);
glVertex3f(0.0, 0.0, 0.0);
for I := 0 to U - 1 do begin
glVertex3fv(@A[I, 0]);
end;
glVertex3fv(@A[0, 0]);
glEnd;

// Side
glBegin(GL_TRIANGLE_STRIP);
for I := 1 to V do begin
for J := 0 to U - 1 do begin
glVertex3fv(@A[J, I - 1]);
glVertex3fv(@A[J, I]);
end;
// Two last vertices (the first two)
glVertex3fv(@A[0, I - 1]);
glVertex3fv(@A[0, I]);
end;
glEnd;

// Top circle
glBegin(GL_TRIANGLE_FAN);
glVertex3fv(@CenterTop);
for I := 0 to U - 1 do begin
glVertex3fv(@A[I, V]);
end;
glVertex3fv(@A[0, V]);
glEnd;

glEndList;
end;

Sorry, I forgot something.

U, V are Integer
Other are Single or GLFloat

There is no normals calculation in this code. Do it yourself.