For the next part, let's use the [Perspective ruler] to draw a background.
One method to create one is to use the [Layer] menu...
...[Ruler - frame] and select [Create Perspective Ruler]
This will open a window to select how many vanishing points the rulers is going to have.
In CLIP STUDIO PAINT, you can create rulers for one, two or three-point perspectives.
I'll show you what a 3 points perspective ruler looks like, so I choose 3 points and click OK.
With this, the perspective ruler will appear with a three vanishing points on the canvas.
You can use the [Object] tool selected parts of the ruler and make adjustments to it.
The horizontal line at the center is the eye level.
If you want to change the eye level, drag the green point in the center of the ruler
The blue dots on the left and right are the vanishing points of the perspective.
You can also move these by clicking and dragging.
To move and rotate the eye level angle click and drag the respective line.
To match the image of the background I want to draw, I adjust the position of the ruler.
I zoom in on the area where the background will be drawn in the [Navigator] palette.
First, I'll switch tools to the pen tool and draw a sketch.
As long as the "Snap to the ruler" setting is ON...
...the layer on which this ruler is placed allows you to cleanly draw lines towards the vanishing points...
...wherever you place the brush on the canvas.
The background sketch is complete.
Next, I'll use the ruler and pen to ink the line drawing.
This time, I'm going to create a new vector layer.
Before inking, I reduce the transparency of the draft layer.
It's possible to move rulers between layers,...
...so I am going to select the 3-point perspective ruler on the layer in the [Layer] Palette...
...and click and drag it to the vector layer.
You can also duplicate rulers by holding down the "alt/option" key while dragging them to a different layer.
Now I select the pen tool from the [Tool] palette,...
...switch to the [Marker] sub-group and select the [Milli pen] tool.
Since I just follow the ruler when drawing the lines, there are parts that overlap.
But it is very easy to erase such lines with the vector eraser.
Once the inking is complete, I create a new raster layer and paint in the black solid parts.
Lastly, I move the layer into the frame folder, apply the layer mask,...
...and hide the parts that are visible outside the frame.