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io.data2viz.geo.projection.Resample.kt Maven / Gradle / Ivy
package io.data2viz.geo.projection
import io.data2viz.geo.ModifiedStream
import io.data2viz.geo.asin
import io.data2viz.geo.cartesian
import io.data2viz.math.EPSILON
import io.data2viz.math.toRadians
import kotlin.math.abs
import kotlin.math.atan2
import kotlin.math.cos
import kotlin.math.sqrt
const val MAX_DEPTH = 16
val COS_MIN_DISTANCE = cos(30.0.toRadians())
fun resample(project: Projectable, delta2: Double) = if(delta2 != .0) _resample(project, delta2) else resampleNone(project)
private fun resampleNone(project: Projectable): (Stream)->Stream {
return { stream: Stream ->
object : ModifiedStream(stream) {
override fun point(x: Double, y: Double, z: Double) {
val p = project.project(x, y)
stream.point(p[0], p[1], 0.0)
}
}
}
}
private fun _resample(project: Projectable, delta2: Double): (Stream)->Stream {
fun resampleLineTo(x0: Double, y0: Double, lambda0: Double, a0: Double, b0: Double, c0: Double,
x1: Double, y1: Double, lambda1: Double, a1: Double, b1: Double, c1: Double,
depth: Int, stream: Stream) {
var newDepth = depth
val dx = x1 - x0
val dy = y1 - y0
val d2 = dx * dx + dy * dy
if(d2 > 4 * delta2 && newDepth != 0) {
newDepth--
var a = a0 + a1
var b = b0 + b1
var c = c0 + c1
val m = sqrt(a * a + b * b + c * c)
c /= m
val phi2 = c.asin
val lambda2 = when {
abs(abs(c) - 1) < EPSILON || abs(lambda0 - lambda1) < EPSILON -> (lambda0 + lambda1) / 2
else -> atan2(b, a)
}
val p = project.project(lambda2, phi2)
val x2 = p[0]
val y2 = p[1]
val dx2 = x2 - x0
val dy2 = y2 - y0
val dz = dy * dx2 - dx * dy2
if(dz * dz / d2 > delta2 // perpendicular projected distance
|| abs((dx * dx2 + dy * dy2) / d2 - 0.5) > 0.3 // midpoint close to an end
|| a0 * a1 + b0 * b1 + c0 * c1 < COS_MIN_DISTANCE) { // angular distance
a /= m
b /= m
resampleLineTo(x0, y0, lambda0, a0, b0, c0, x2, y2, lambda2, a, b, c, newDepth, stream)
stream.point(x2, y2, 0.0)
resampleLineTo(x2, y2, lambda2, a, b, c, x1, y1, lambda1, a1, b1, c1, newDepth, stream)
}
}
}
return { stream: Stream ->
object : Stream {
// First point
var lambda00 = Double.NaN
var x00 = Double.NaN
var y00 = Double.NaN
var a00 = Double.NaN
var b00 = Double.NaN
var c00 = Double.NaN
// Previous point
var lambda0 = Double.NaN
var x0 = Double.NaN
var y0 = Double.NaN
var a0 = Double.NaN
var b0 = Double.NaN
var c0 = Double.NaN
var currentPoint = ::defaultPoint
var currentLineStart = ::defaultLineStart
var currentLineEnd = ::defaultLineEnd
var currentPolygonStart = { stream.polygonStart(); currentLineStart = ::ringStart }
var currentPolygonEnd = { stream.polygonEnd(); currentLineStart = ::defaultLineStart }
override fun lineEnd() = currentLineEnd()
override fun lineStart() = currentLineStart()
override fun point(x: Double, y: Double, z: Double) = currentPoint(x, y, z)
override fun polygonEnd() = currentPolygonEnd()
override fun polygonStart() = currentPolygonStart()
private fun defaultPoint(x: Double, y: Double, z: Double) {
val p = project.project(x, y)
stream.point(p[0], p[1], 0.0)
}
private fun defaultLineStart() {
x0 = Double.NaN
currentPoint = ::linePoint
stream.lineStart()
}
private fun linePoint(lambda: Double, phi: Double, z: Double) {
val c = cartesian(doubleArrayOf(lambda, phi))
val p = project.project(lambda, phi)
resampleLineTo(x0, y0, lambda0, a0, b0, c0, p[0], p[1], lambda, c[0], c[1], c[2], MAX_DEPTH, stream)
x0 = p[0]
y0 = p[1]
lambda0 = lambda
a0 = c[0]
b0 = c[1]
c0 = c[2]
stream.point(x0, y0, z)
}
private fun defaultLineEnd() {
currentPoint = ::defaultPoint
stream.lineEnd()
}
private fun ringStart() {
defaultLineStart()
currentPoint = ::ringPoint
currentLineEnd = ::ringEnd
}
private fun ringPoint(lambda: Double, phi: Double, z: Double) {
lambda00 = lambda
linePoint(lambda, phi, 0.0)
x00 = x0
y00 = y0
a00 = a0
b00 = b0
c00 = c0
currentPoint = ::linePoint
}
private fun ringEnd() {
resampleLineTo(x0, y0, lambda0, a0, b0, c0, x00, y00, lambda00, a00, b00, c00, MAX_DEPTH, stream)
currentLineEnd = ::defaultLineEnd
lineEnd()
}
}
}
}
