I've been having trouble using the current ArtRage rulers for Perspective work.
The Pin can be accidentally moved, and the ruler size can be changed, both of which throw off your drawings. You can't swivel the ruler around the pin if it keeps moving to a new location. Also, if the ruler gets fatter and skinnier, you are no longer drawing lines towards the same ending point, making it worthless for perspective.
In addition, the line you draw along the ruler is unsteady, and a person can often 'lift' the drawing tool away from the edge. I know this emulates a real ruler, but is not what I need when creating a drawing.
Therefore, I am suggesting a 'Slotted Ruler' tool:
The end point of this ruler (the pin) can't be moved, it always exists at the end of the ruler.
The edges of the ruler are not used, instead the drawing takes place along the length of the center slot. The length of the ruler is variable, but since the edges are not used, this is not a problem.
The ruler is free to rotate around the end point (pin) without restrictions, but as long as the 'lock' icon is toggled ON - the ruler is fixed and cannot be repositioned from that end point.
When the artist positions the drawing tool along the slotted center, a clean line is drawn, accidentally moving away from the edge is not allowed, the tool understands that you want to draw a clean, perfectly straight line.
Hope this makes sense, and that it will be implemented.