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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' or shape.mode == 'rectangle' or shape.mode == 'square' then
return geom.on_polygon(x,y, drawing, shape)
elseif shape.mode == 'circle' then
local center = drawing.points[shape.center]
return geom.dist(center.x,center.y, x,y) == shape.radius
elseif shape.mode == 'arc' then
local center = drawing.points[shape.center]
local dist = geom.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
-- are (x3,y3) and (x4,y4) on the same side of the line between (x1,y1) and (x2,y2)
function geom.same_side(x1,y1, x2,y2, x3,y3, x4,y4)
if x1 == x2 then
return math.sign(x3-x1) == math.sign(x4-x1)
end
if y1 == y2 then
return math.sign(y3-y1) == math.sign(y4-y1)
end
local m = (y2-y1)/(x2-x1)
return math.sign(m*(x3-x1) + y1-y3) == math.sign(m*(x4-x1) + y1-y4)
end
function math.sign(x)
if x > 0 then
return 1
elseif x == 0 then
return 0
elseif x < 0 then
return -1
end
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 = geom.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
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