AutoLISP Routines

Two survey points with known levels, and a straight fall between them. INTERP works out where each whole contour crosses that line and marks it — the donkey work of drawing contours from spot levels. What ContourInterp does Run it along each side of a triangle of survey points and the contour crossings are all there to be joined up. The arithmetic. … [Read more...] about INTERP LISP: Mark Contour Crossings Between Spot Levels

CLOCKFACE draws a longcase — grandfather — clock: case, hood, dial, hour marks and pendulum, with the hands set to the current time or to any time you give. What ClockFace does Draw mode produces real geometry you can keep, plot and edit. A clock face is a genuine thing to put on a drawing: schools, stations, foyers. Live mode is the original … [Read more...] about CLOCKFACE LISP: Draw a Longcase Clock, or Run It Live

Window a rectangle and everything outside it disappears — anything that crosses the edge is trimmed off cleanly at the boundary rather than left hanging. Or do the reverse, and punch the rectangle out of the drawing. What ClipBox does This is what you want when lifting a detail out of a large plan, cutting a supplied drawing down to the bit you actually … [Read more...] about CLIPBOX LISP: Clip a Drawing to a Rectangle in AutoCAD

CHAINAGE labels how far along you are at every vertex of a polyline — the running distance from the start, written beside each point. Roads, drains, kerb lines, fences, cable routes, section lines: anything measured from one end. What Chainage does Three ways of writing it. Distance is a plain running length — 0, 12.5, 31.75. Station is the … [Read more...] about CHAINAGE LISP: Label Running Distance Along a Polyline

CEILGRID fills a room outline with a suspended ceiling grid at the tile size you give, at any rotation, and centred so the cut tiles come out equal on opposite walls — which is what a ceiling contractor will do on site, and therefore what the drawing should show. What CeilingGrid does Pick the room boundary, give the tile size, and nudge the grid until the … [Read more...] about CEILGRID LISP: Lay a Suspended Ceiling Grid in a Room

A cannon at one end, an ammunition dump somewhere down range, and a parabola between them. Set the elevation and the muzzle velocity and try to land a shot on the target. What Cannon does It is a game, but the trajectory is honest. The shot follows x = x₀ + v cos(a) ty = y₀ + v sin(a) t - g t² which is projectile motion with no drag. … [Read more...] about CANNON LISP: An Artillery Game Inside AutoCAD