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author | Kartik K. Agaram <vc@akkartik.com> | 2022-05-17 21:18:17 -0700 |
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committer | Kartik K. Agaram <vc@akkartik.com> | 2022-05-17 21:34:55 -0700 |
commit | de495ae0f1574ee1f0fb803ff05c77aaf04f13fc (patch) | |
tree | 9fc98b05410ac66763d390703b5ff8b78eba6f68 /geom.lua | |
parent | 91ce333ae0f617ef4eb6638faf66bbe159f25a0d (diff) | |
download | text.love-de495ae0f1574ee1f0fb803ff05c77aaf04f13fc.tar.gz |
several more modules
This is probably not ideal; let's see how it goes..
Diffstat (limited to 'geom.lua')
-rw-r--r-- | geom.lua | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/geom.lua b/geom.lua new file mode 100644 index 0000000..7b71df3 --- /dev/null +++ b/geom.lua @@ -0,0 +1,131 @@ +local geom = {} + +function geom.on_shape(x,y, drawing, shape) + if shape.mode == 'freehand' then + return geom.on_freehand(x,y, drawing, shape) + elseif shape.mode == 'line' then + return geom.on_line(x,y, drawing, shape) + elseif shape.mode == 'manhattan' then + return x == drawing.points[shape.p1].x or y == drawing.points[shape.p1].y + elseif shape.mode == 'polygon' then + return geom.on_polygon(x,y, drawing, shape) + elseif shape.mode == 'circle' then + local center = drawing.points[shape.center] + return math.dist(center.x,center.y, x,y) == shape.radius + elseif shape.mode == 'arc' then + local center = drawing.points[shape.center] + local dist = math.dist(center.x,center.y, x,y) + if dist < shape.radius*0.95 or dist > shape.radius*1.05 then + return false + end + return geom.angle_between(center.x,center.y, x,y, shape.start_angle,shape.end_angle) + elseif shape.mode == 'deleted' then + else + print(shape.mode) + assert(false) + end +end + +function geom.on_freehand(x,y, drawing, shape) + local prev + for _,p in ipairs(shape.points) do + if prev then + if geom.on_line(x,y, drawing, {p1=prev, p2=p}) then + return true + end + end + prev = p + end + return false +end + +function geom.on_line(x,y, drawing, shape) + local p1,p2 + if type(shape.p1) == 'number' then + p1 = drawing.points[shape.p1] + p2 = drawing.points[shape.p2] + else + p1 = shape.p1 + p2 = shape.p2 + end + if p1.x == p2.x then + if math.abs(p1.x-x) > 5 then + return false + end + local y1,y2 = p1.y,p2.y + if y1 > y2 then + y1,y2 = y2,y1 + end + return y >= y1 and y <= y2 + end + -- has the right slope and intercept + local m = (p2.y - p1.y) / (p2.x - p1.x) + local yp = p1.y + m*(x-p1.x) + if yp < 0.95*y or yp > 1.05*y then + return false + end + -- between endpoints + local k = (x-p1.x) / (p2.x-p1.x) + return k > -0.05 and k < 1.05 +end + +function geom.on_polygon(x,y, drawing, shape) + local prev + for _,p in ipairs(shape.vertices) do + if prev then + if geom.on_line(x,y, drawing, {p1=prev, p2=p}) then + return true + end + end + prev = p + end + return geom.on_line(x,y, drawing, {p1=shape.vertices[1], p2=shape.vertices[#shape.vertices]}) +end + +function geom.angle_with_hint(x1, y1, x2, y2, hint) + local result = geom.angle(x1,y1, x2,y2) + if hint then + -- Smooth the discontinuity where angle goes from positive to negative. + -- The hint is a memory of which way we drew it last time. + while result > hint+math.pi/10 do + result = result-math.pi*2 + end + while result < hint-math.pi/10 do + result = result+math.pi*2 + end + end + return result +end + +-- result is from -π/2 to 3π/2, approximately adding math.atan2 from Lua 5.3 +-- (LÖVE is Lua 5.1) +function geom.angle(x1,y1, x2,y2) + local result = math.atan((y2-y1)/(x2-x1)) + if x2 < x1 then + result = result+math.pi + end + return result +end + +-- is the line between x,y and cx,cy at an angle between s and e? +function geom.angle_between(ox,oy, x,y, s,e) + local angle = math.angle(ox,oy, x,y) + if s > e then + s,e = e,s + end + -- I'm not sure this is right or ideal.. + angle = angle-math.pi*2 + if s <= angle and angle <= e then + return true + end + angle = angle+math.pi*2 + if s <= angle and angle <= e then + return true + end + angle = angle+math.pi*2 + return s <= angle and angle <= e +end + +function geom.dist(x1,y1, x2,y2) return ((x2-x1)^2+(y2-y1)^2)^0.5 end + +return geom |