pixie/experiments/trapezoid0.nim

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2021-11-28 03:06:14 +00:00
import algorithm, bumpy, chroma, pixie, pixie/images, pixie/paths, print,
sequtils, vmath
printColors = false
proc intersectsInner*(a, b: Segment, at: var Vec2): bool {.inline.} =
## Checks if the a segment intersects b segment.
## If it returns true, at will have point of intersection
let
s1 = a.to - a.at
s2 = b.to - b.at
denominator = (-s2.x * s1.y + s1.x * s2.y)
s = (-s1.y * (a.at.x - b.at.x) + s1.x * (a.at.y - b.at.y)) / denominator
t = (s2.x * (a.at.y - b.at.y) - s2.y * (a.at.x - b.at.x)) / denominator
if s > 0 and s < 1 and t >= 0 and t <= 1:
at = a.at + (t * s1)
return true
type Trapezoid = object
nw, ne, se, sw: Vec2
proc roundBy*(v: Vec2, n: float32): Vec2 {.inline.} =
result.x = sign(v.x) * round(abs(v.x) / n) * n
result.y = sign(v.y) * round(abs(v.y) / n) * n
proc pathToTrapezoids(p: Path): seq[Trapezoid] =
var polygons = p.commandsToShapes()
const q = 1/256.0
# Creates segment q, quantize and remove verticals.
var segments1: seq[Segment]
for shape in polygons:
for s in shape.segments:
var s = s
s.at = s.at.roundBy(q)
s.to = s.to.roundBy(q)
if s.at.y != s.to.y:
segments1.add(s)
#print segments1
# Handle segments overlapping each other:
# var segments1: seq[Segment]
# while segments0.len > 0:
# var a = segments0.pop()
# var collision = false
# for b in segments0:
# if a != b:
# var at: Vec2
# if a.intersectsInner(b, at):
# print "seg2seg intersects!", a, b, at
# quit()
# if not collision:
# segments1.add(a)
# There is probably a clever way to insert-sort them.
var yScanLines: seq[float32]
for s in segments1:
if s.at.y notin yScanLines:
yScanLines.add s.at.y
if s.to.y notin yScanLines:
yScanLines.add s.to.y
yScanLines.sort()
var segments: seq[Segment]
while segments1.len > 0:
#print segments1.len, segments.len
var s = segments1.pop()
var collision = false
for y in yScanLines:
var at: Vec2
if intersects(line(vec2(0, y), vec2(1, y)), s, at):
at = at.roundBy(q)
at.y = y
if s.at.y != at.y and s.to.y != at.y:
#print "seg2yline intersects!", a, y, at
collision = true
var s1 = segment(s.at, at)
var s2 = segment(at, s.to)
#print s.length, "->", s1.length, s2.length
segments1.add(s1)
segments1.add(s2)
break
if not collision:
segments.add(s)
#print segments
# sort at/to in segments
for s in segments.mitems:
if s.at.y > s.to.y:
swap(s.at, s.to)
#print segments
#print yScanLines
for yScanLine in yScanLines[0..^2]:
var scanSegments: seq[Segment]
for s in segments:
if s.at.y == yScanLine:
scanSegments.add(s)
scanSegments.sort(proc(a, b: Segment): int =
cmp(a.at.x, b.at.x))
if scanSegments.len mod 2 != 0:
print "error???"
print yScanLine
print scanSegments
quit()
# if scanSegments.len == 0:
# print "error???"
# print yScanLine
# print scanSegments
# quit()
# TODO: winding rules will go here
for i in 0 ..< scanSegments.len div 2:
let
a = scanSegments[i*2+0]
b = scanSegments[i*2+1]
assert a.at.y == b.at.y
assert a.to.y == b.to.y
#assert a.at.x < b.at.x
#assert a.to.x < b.to.x
result.add(
Trapezoid(
nw: a.at,
ne: b.at,
se: b.to, # + vec2(0,0.7),
sw: a.to # + vec2(0,0.7)
)
)
proc trapFill(image: Image, t: Trapezoid, color: ColorRGBA) =
# assert t.nw.y == t.ne.y
# assert t.sw.y == t.se.y
let
height = t.sw.y - t.nw.y
minY = clamp(t.nw.y, 0, image.height.float)
maxY = clamp(t.sw.y, 0, image.height.float)
for y in minY.int ..< maxY.int:
var yRate, minX, maxX: float32
yRate = clamp((y.float - t.nw.y) / height, 0, 1)
minX = clamp(lerp(t.nw.x, t.sw.x, yRate).round, 0, image.width.float)
maxX = clamp(lerp(t.ne.x, t.se.x, yRate).round, 0, image.width.float)
for x in minX.int ..< maxX.int:
image.setRgbaUnsafe(x, y, color)
proc drawTrapezoids(image: Image, trapezoids: seq[Trapezoid]) =
for trapezoid in trapezoids:
image.trapFill(trapezoid, rgba(0, 0, 0, 255))
# for trapezoid in trapezoids:
# var p = newPath()
# p.moveTo(trapezoid.nw)
# p.lineTo(trapezoid.ne)
# p.lineTo(trapezoid.se)
# p.lineTo(trapezoid.sw)
# p.closePath()
# image.fillPath(p, rgba(0, 0, 0, 255))
# image.strokePath(p, rgba(255, 0, 0, 255))
block:
# Rect
print "rect"
var image = newImage(200, 200)
image.fill(rgba(255, 255, 255, 255))
var p: Path
p.moveTo(50, 50)
p.lineTo(50, 150)
p.lineTo(150, 150)
p.lineTo(150, 50)
p.closePath()
var trapezoids = p.pathToTrapezoids()
image.drawTrapezoids(trapezoids)
image.writeFile("experiments/trapezoids/rect.png")
block:
# Rhombus
print "rhombus"
var image = newImage(200, 200)
image.fill(rgba(255, 255, 255, 255))
var p: Path
p.moveTo(100, 50)
p.lineTo(150, 100)
p.lineTo(100, 150)
p.lineTo(50, 100)
p.closePath()
var trapezoids = p.pathToTrapezoids()
image.drawTrapezoids(trapezoids)
image.writeFile("experiments/trapezoids/rhombus.png")
block:
# heart
print "heart"
var image = newImage(400, 400)
image.fill(rgba(255, 255, 255, 255))
var p = parsePath("""
M 40 120 A 80 80 90 0 1 200 120 A 80 80 90 0 1 360 120
Q 360 240 200 360 Q 40 240 40 120 z
""")
var trapezoids = p.pathToTrapezoids()
image.drawTrapezoids(trapezoids)
image.writeFile("experiments/trapezoids/heart.png")
block:
# l
print "l"
var image = newImage(500, 800)
image.fill(rgba(255, 255, 255, 255))
var p = parsePath("""
M 236 20 Q 150 22 114 57 T 78 166 V 790 L 171 806 V 181 Q 171 158 175 143 T 188 119 T 212 105.5 T 249 98 Z
""")
#image.strokePath(p, rgba(0, 0, 0, 255))
var trapezoids = p.pathToTrapezoids()
image.drawTrapezoids(trapezoids)
image.writeFile("experiments/trapezoids/l.png")
block:
# g
print "g"
var image = newImage(500, 800)
image.fill(rgba(255, 255, 255, 255))
var p = parsePath("""
M 406 538 Q 394 546 359.5 558.5 T 279 571 Q 232 571 190.5 556 T 118 509.5 T 69 431 T 51 319 Q 51 262 68 214.5 T 117.5 132.5 T 197 78.5 T 303 59 Q 368 59 416.5 68.5 T 498 86 V 550 Q 498 670 436 724 T 248 778 Q 199 778 155.5 770 T 80 751 L 97 670 Q 125 681 165.5 689.5 T 250 698 Q 333 698 369.5 665 T 406 560 V 538 Z M 405 152 Q 391 148 367.5 144.5 T 304 141 Q 229 141 188.5 190 T 148 320 Q 148 365 159.5 397 T 190.5 450 T 235.5 481 T 288 491 Q 325 491 356 480.5 T 405 456 V 152 Z
""")
#image.strokePath(p, rgba(0, 0, 0, 255))
var trapezoids = p.pathToTrapezoids()
image.drawTrapezoids(trapezoids)
image.writeFile("experiments/trapezoids/g.png")