1. Take the structure diagram of a cuboid as an example. First, determine the composition. The composition of a cuboid depends first on the placement of the cuboid. If it is placed horizontally, the composition generally adopts horizontal composition, and the vertical composition generally adopts vertical composition. The composition of a single cube in the picture can be above the center.
2. Fully determine the relationship between the size of the object and the picture, and measure its aspect ratio. Pay attention to the head-up angle. You don't need to think much when drawing the front, just draw the vertical line directly. When you have a little bow angle, pay attention to the perspective change of the cuboid, which is wide at the top and narrow at the bottom, as shown below.
3. Sketch the internal structure line of the object from the perspective of change. The key point is to describe the external structure line, find out the dividing line between light and shade and the position of projection, and the key point is to describe the dividing line between light and shade and the dark part. After paving the dark tone, the projection position is also paved with tone.
4. Take the shading method of a cuboid as an example, take the shape according to the structural drawing method, and find out the projection position and shape without drawing the internal structural line.
5. Draw a long line on the side of the pen, put the dark side and the projected tone together, and then emphasize the projection and the dark side respectively. Note that the color of the projection is heavier than that of the dark side. The top left corner of the dark side is the heaviest part, and its diagonal position is reflective and the brightest part of the dark side.
6. Gently wipe the color matching parts with a brush or paper towel. Don't use too much force to avoid rubbing lead powder into the paper, which will cause the reflection of the picture to be not deep.
7. Use long lines to lay out the background and countertops in the drawing. Again, don't do it all at once. Don't draw too much at a time. It is the first time to determine the relationship between big black and white with the side face. The background is dark and the countertop is bright.
8. Make a comprehensive and in-depth picture. The most important part is the edge facing us, which is also the dividing line between light and shade of a cuboid. It is the solid part with the strongest contrast between light and shade in the picture, and its diagonal position is the imaginary part with the weakest contrast between light and shade. For the heaviest part of the picture, you must draw it several times, not once. Every time you draw a picture, you should compare it as a whole, and the colors of other parts should keep up, so as to keep the relationship between black, white and gray in the picture correct and accurate.