This example is for Processing 3+. If you have a previous version, use the examples included with your software. If you see any errors or have suggestions, please let us know.

Vertices by Simon Greenwold.

Draw a cylinder centered on the y-axis, going down from y=0 to y=height. The radius at the top can be different from the radius at the bottom, and the number of sides drawn is variable.

void setup() {
size(640, 360, P3D);
}

void draw() {
background(0);
lights();
translate(width / 2, height / 2);
rotateY(map(mouseX, 0, width, 0, PI));
rotateZ(map(mouseY, 0, height, 0, -PI));
noStroke();
fill(255, 255, 255);
translate(0, -40, 0);
drawCylinder(10, 180, 200, 16); // Draw a mix between a cylinder and a cone
//drawCylinder(70, 70, 120, 64); // Draw a cylinder
//drawCylinder(0, 180, 200, 4); // Draw a pyramid
}

float angle = 0;
float angleIncrement = TWO_PI / sides;
for (int i = 0; i < sides + 1; ++i) {
angle += angleIncrement;
}
endShape();

// If it is not a cone, draw the circular top cap
angle = 0;
beginShape(TRIANGLE_FAN);

// Center point
vertex(0, 0, 0);
for (int i = 0; i < sides + 1; i++) {
angle += angleIncrement;
}
endShape();
}

// If it is not a cone, draw the circular bottom cap