{graphics: g, :timer, :mouse, :keyboard} = love

export *

barycentric_coords = (x1, y1, x2, y2, x3,y3, px, py) ->

det = (y2 - y3) * (x1 - x3) + (x3 - x2) * (y1 - y3)

b1 = (y2 - y3) * (px - x3) + (x3 - x2) * (py - y3)

b2 = (y3 - y1) * (px - x3) + (x1 - x3) * (py - y3)

b1 = b1 / det

b2 = b2 / det

b3 = 1 - b1 - b2

b1, b2, b3

pt_in_tri = (...) ->

b1, b2, b3 = barycentric_coords ...

return false if b1 < 0 or b2 < 0 or b3 < 0

true

class Quad

a: 255

-- clockwise from top left

new: (x1, y1, x2, y2, x3, y3, x4, y4) =>

@[1] = x1

@[2] = y1

@[3] = x2

@[4] = y2

@[5] = x3

@[6] = y3

@[7] = x4

@[8] = y4

draw: (top_r, top_g, top_b, bot_r=top_r, bot_g=top_g, bot_b=top_b) =>

g.setColor top_r, top_g, top_b, @a

g.triangle "fill",

@[1], @[2],

@[3], @[4],

@[5], @[6]

g.setColor bot_r, bot_g, bot_b, @a

g.triangle "fill",

@[1], @[2],

@[5], @[6],

@[7], @[8]

-- g.setColor 255,100,100

-- g.point @[1], @[2]

-- g.setColor 100,255,100

-- g.point @[3], @[4]

-- g.setColor 100,100,255

-- g.point @[5], @[6]

-- g.setColor 100,255,255

-- g.point @[7], @[8]

-- g.setColor 255,255,255

contains_pt: (x,y) =>

return true if pt_in_tri @[1], @[2],

@[3], @[4],

@[5], @[6],

x,y

return true if pt_in_tri @[1], @[2],

@[5], @[6],

@[7], @[8],

x,y

false

__tostring: =>

"vec2d<(%f, %f), (%f, %f), (%f, %f), (%f, %f)>"\format unpack @

class TrapSystem

new: (@skew=0) =>

-- project to Quad

project_box: (box) =>

ax, ay, bx, by = box\unpack2!

x1, y1 = @project ax, ay

x2, y2 = @project bx, ay

x3, y3 = @project bx, by

x4, y4 = @project ax, by

Quad x1, y1, x2, y2, x3, y3, x4, y4

-- form system to euclidean

project: (x, y) =>

x * (@skew * y + 1), y * (1 - @skew^0.3)

-- euclidean to system

unproject: (x, y) =>

sy = y / (1 - @skew^0.3)

x / (@skew * sy + 1), sy

class SystemTest

skew: 0.003

draw: =>

system = TrapSystem @skew

g.push!

g.translate g.getWidth!/2, g.getHeight!/2

g.scale 3, 3

for y=-100, 100, 10

for x=-100, 100, 10

g.point system\project x,y

g.pop!