You can use the perspective ruler in CLIP STUDIO PAINT to create drawings using perspective.
In this lesson, I’ll show you how to make compositions with one-point perspective. How can we draw the lines of a window frame correctly at even intervals in a composition with depth?
Please read the following article to learn how to use perspective rulers.
 Creating a one-point perspective ruler
① From the tool palette, click the [Ruler] tool, then the sub tool [Perspective ruler].
② Set the position of the vanishing point. Use the two guide lines to set the position of the vanishing point.
Once you have set one vanishing point, the horizontal and vertical lines will snap into place.
You can also create a one-point perspective ruler from the [Layer] menu, by going to [Ruler - Frame] > [Create Perspective Ruler], then, in the [Create Perspective Ruler] dialog box, click [1 point perspective].
In this case, the vanishing point of the one-point perspective will be placed in the center of the canvas. If you want to make a composition with a different location for the vanishing point, you can adjust it by going to the [Tool] palette and using the [Perspective ruler] tool.
Once you have made the one-point perspective ruler, you can snap the movements of pens and brushes to the vanishing point, the horizontal direction, or the vertical direction.
In this example, all the lines were drawn using the perspective ruler.
With the one-point perspective ruler, you can snap the horizontal and vertical directions onto the eye level (indicated with a red arrow).
Drag the [+] symbol on the eye level to adjust the angle of the eye level.
By doing this, you can change the camera to be at a slanted angle.
 Drawing lines at regular intervals using traditional methods (1)
You can make compositions with depth using perspective.
The following will explain how to equally divide the window frame shown in the red box.
In a three-dimensional drawing with perspective, you need to divide the section according to the perspective in order to do something like divide this window into four equal sections.
If you draw lines spaced equally according to the actual distance between them on the canvas, they won’t be equally spaced in terms of the perspective depth.
In this lesson, I’ll use this example of the window to show you how to draw lines that are equally spaced according to the perspective depth.
First, let’s look at how to divide spaces on a flat surface with no perspective.
■ Using auxiliary lines to divide a rectangle into two
First, let’s look at how to divide a rectangle on a flat surface. I’m going to divide it in half using a vertical line.
① I draw two diagonal lines across the rectangle.
The point where these lines intersect is the halfway point in both horizontal and vertical directions.
② I draw a straight vertical line where the diagonal lines meet to divide the rectangle into two equal parts.
③ You can divide the rectangle even further using this line.
I draw more diagonal lines and add vertical lines where they meet to divide the rectangle into four.
 Drawing lines at regular intervals using traditional methods (2)
This time I’m going to divide this window on the right into three equal parts. As before, let’s look at how to divide spaces on a flat surface with no perspective.
■1. Using auxiliary lines to divide a rectangle into three
We start off in the same way by dividing a rectangle into two, but add another step to divide it into three.
① I draw two diagonal lines across the rectangle and draw a vertical line where they meet. So far it’s exactly the same process as dividing a rectangle into two.
② Now, in this rectangle divided into two, I draw two more diagonal lines (shown in green). The points where the green and blue lines intersect are the points that will divide the rectangle into three equal parts.
③ You can draw vertical lines where these lines intersect to divide the rectangle into three.
■2. Applying this method with perspective
I use the same method as before in the shape that has been distorted to match the perspective.
① I draw diagonal lines and find the center point.
② I work out the location of the halfway point and draw a line.
③ From this halfway line, I draw two more diagonal lines.
④ At the points where the lines intersect, I draw the lines to divide the rectangle into three.
Using this method, you can equally divide rectangles that have been distorted by perspective.
 Drawing equally spaced lines using the perspective ruler grid
Now that you understand how to equally divide shapes, let’s apply the same method to the perspective ruler grid.
① Once I’ve made and adjusted the perspective ruler, I go to the [Tool Property] palette and turn the [Grid] on. This displays a grid that matches the perspective.
To work on the vertical lines of the windows on the walls, I click the [YZ plane].
The XZ plane displays a grid in the horizontal direction.
The YZ plane displays a grid in the vertical direction (front and back).
② I move the green circle to adjust the grid to line up with the rectangular windows.
To adjust the number of divisions in the grid, I go to the [Tool Property] palette, and change the number in [Grid size].
To draw the lines, I go to the [View] menu and check [Snap to Grid], or go to the [Command] bar and turn the [Snap to Grid] icon on.
 Transforming shapes to match the perspective
If you want to make more complex shapes match up with the perspective, you can use the [Free Transform] tool.
① I prepared this flat diagram. I want to use this rough outline of a room layout to help me draw the furniture.
I’ve drawn the walls, floor, and ceiling of the room.
② I go to the [Edit] menu > [Transform] > [Free Transform], and transform the shape.
I move the handles at the four corners to match up with the shape of the room. By doing this, the shape transforms to have depth matching the perspective.
③ Once I’ve finished doing this, I go to the [Tool Property] palette and click the circle button [◯] or press the enter key to confirm the shape.
④ Using the transformed room layout sketch and the perspective ruler, I draw the furniture.
NOTE: Transforming vector width
If you transform using the [Free Transform] tool, the line thickness will also change.
To transform a shape without changing the line thickness, draw the shape on a vector layer and make sure [Change vector width] is off before transforming.