Tuesday, April 26, 2011

One way to sketch a cube

The cube is the basis of measurement for every perspective drawing (one unit long and one unit high).  It can be proportioned back and up to make a more complex rectilinear object (like two units long and three units high).  Almost any object can be modeled, using a cube (or multiple cubes) as a template.  So, sketching a cube is something that we, as designers, should practice ... if you can sketch cube and get its perspective right, you can sketch almost anything.

Step 1: THE BASE
Sketch a ground line parallel to the bottom of the paper.  Sketch in a leading edge perpendicular to that ground line, then draw the bottom of the cube.  One line should accelerate back to its vanishing point quicker than the other (the resulting angles are different: x<y).
Step 2: FIRST BACK EDGE
Pick a height for your cube.  Mark it on the leading edge line.  Translate the exact length of that line to the bottom edge, come toward the leading edge line to account for the foreshortening that occurs and then sketch a vertical line as the back edge.
Step 3: OTHER BACK EDGE
Translate the exact length of the leading edge and the midpoint of the leading edge to the bottom edge and mark.  The back edge should be in between these marks (more toward the midpoint).  Sketch a vertical line as the back edge.
Step 4: TOP
Ghosting over the cube edges that are already there (1+2), turn the page in a rhythm to continue the top back edge (3).

You should notice that you turn the page less for the smaller angled side (this side).
Step 5: TOP CONT.
Ghosting over the cube edges that are already there (1+2), turn the page in a rhythm to continue the other top back edge (3).

You should notice that you turn the page more for the bigger angled side (this side).
Step 6: FIX
Adjust the sides of the cube to make it look more like a cube.  This takes practice.  Sometimes you can spot things better if you hold it upside down.  You can also double check your work by doing a reverse draft and making sure your plan is a square.

Last step: DARKEN
Go back and darken the edges that you would like the viewer to see.