4. Draw the vertical foreshortened circle end of the tube.
5. Using the line you have already drawn in direction NE as reference, draw the thickness of the tube. Draw this line from the very top edge of the vertical foreshortened circle. Notice in my illustration how this line is slanted just a tad bit more than the bottom line, making the tube taper as it recedes away from your eye. This is an application of the drawing law of size to the tube. These lines will eventually merge together at a distant vanishing point, which we will get to later in the book.
6. Curve the far end of the tube a bit more than the near edge. The law of size not only shrinks things as they move away from your eye; it also distorts images. Thus, the far edge is more curved than the near edge.
7. Begin drawing the near contour lines on the surface of the tube. Notice how these contour lines curve a bit more as they move away from your eye.
8. Complete the contour lines. Continue to curve them more as they move away from your eye.
9. To create the illusion of a hollow tube, draw the inside contour lines, following the outside far edge of the initial foreshortened circle. Yes, even these internal contour lines need to curve more as they move away from your eye.
10. Determine the position of your light source. Using the curve of your interior contour lines, add shading to the inside of the tube.
11. Draw the cast shadow with a guide line in direction SE.
12. Shade the tube with curving contour lines. This technique of shading with contour lines is an excellent way to create texture and three-dimensional shape.
13. Draw the second tube for this lesson with a guide line in direction NW. Draw a guide dot for the vertical foreshortened circle. Draw the vertical foreshortened circle. Draw the thickness of the tube receding away in direction NE. Draw the contour lines on the outside of the tube. Voilà! You just defined tube number two as facing in the opposite direction of tube number one. Contour lines are very powerful in defining an object’s direction and position on the paper. To shade this second tube, draw your light source top right and shade opposite.
Lesson 15: Bonus Challenge
Try this visual experiment: Get ahold of an empty paper towel cardboard roll. Using a black Sharpie marker, draw a row of dots about an inch apart down one side of the tube, from opening to opening. It will look like a row of rivets or a zipper. Now, carefully draw a line from each dot around the tube back to the same dot. It’s easier to place your pen on the dot and just roll the tube away from you. Repeat this until you have drawn several rings around the tube.
Hold the tube horizontally in front of your eye at arm’s length. All the rings you have drawn will appear to be vertical lines. Slowly swivel one end toward your eye, just a bit. Notice how the vertical lines now are distorted into contour lines. Experiment with this tube a bit, twisting it back and forth. Now, bend the tube in half and do the same thing . . . interesting, right? See how the contour lines are now climbing across the tube in different directions? Take a look at the long bending tube at the bottom of my sketch page below. Notice how contour lines control the direction of this tube.
1. Now, I’m going to demonstrate the push-and-pull power of contour lines. For the first image, I want to draw the left leg to make it appear to be moving toward you and the right leg to appear to be moving away. Look at my examples below, and draw this important exercise.