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There are! Very good. I will get back to you tomorrow, but this copy paste covers a lot of it:Ok. some things to know about perspective: most books are wrong. They present rules of thumb that look approximately right but don't geometrically work. the geometry isn't that complicated, but it is a bit tricky The location of the vanishing points are determined by the scale of the 90 degree field of view. visually what you see is radians (measures of angle) not distance. Things that are important to know:Thales's theorem. which is used to locate vanishing points.Image plane. for 1 point perspective, the distance from the viewer to the image plane is equal to the viewers height. so if our drawing is a square with the horizon dead center the distance between the horizon and the bottom of the square is equal to the height. that angle is 45 degrees. draw a square in blue.inside that square draw a diamond in red (another square rotated at 45 degrees to the first) with its corners in the midpoints of the square.draw a circle in black tangent to the square where the diamonds corners intersect it.draw a horizon line through 2 points on the diamond running through the center of the circle. ( this should start looking a bit like you are about to summon a demon with a blood sacrifice which is not inaccurate.) What you have here is:- 2 squares 1 circle and a line. what it represents:- 1 point perspective (red square + horizon) [or a 3 point perspective with 2 axis perpendicular to the direction of view]- 90 degree field of view ( black circle) [ every perspective is defined by direction of view and diameter of the 90 degree field of view. to merge 2 different perspectives, the 90 degree fields of view must be the same size, and the direction of view ( the center) must be the same point]- 2 station points. (zenith up and nadir down) represented by the top point or bottom point of the diamond respectively. fold the paper along the horizon line at a 90 degree angle. where that point winds up is the actual location of the cyclopes eye. (from an artists perspective, the viewer of their art must always be either cyclopes or pirates.)- 1 central vanishing point in the center of the circle.- 2 false vanishing points, where the 90 degree field of view circle crosses the horizon. the measured distance from the vanishing point to the false vp is equal to the height of the viewer. The angle between the VP and false VP is 45 degrees.- because of thales theorm, we know that a intersection between any two lines drawn from a false vanishing point to the 90 degree field of view, and back to the other FVP will be a 90 degree angle at the circle. We care because it means that we can't draw squares outside the 90 degree field of view because its not possible to see a 90 degree corner at any angle less than 90 degrees. Now with all that bullshit out of the way, how to draw a square? Draw a line parallel to the horizon.project lines from the ends back to the vanishing point.from the right end of the line, project a [diagonal] line to the left vanishing point. where that diagonal line intersects with the projection to the vanishing point is where the back side of the square is.complete the square. https://www.handprint.com/HP/WCL/tech10.html is what I used to prove perspective. It was the first Correct perspective reference I found. An excellent book on the subject was written by Scott Robertson https://www.amazon.ca/How-Draw-sketching-environments-imagination/dp/1933492759