commonMain.bezierpatches.BezierPatch.kt Maven / Gradle / Ivy
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package org.openrndr.extra.shapes.bezierpatches
import org.openrndr.color.AlgebraicColor
import org.openrndr.color.ColorRGBa
import org.openrndr.color.ConvertibleToColorRGBa
import org.openrndr.math.Matrix44
import org.openrndr.math.Vector2
import org.openrndr.shape.Rectangle
import org.openrndr.shape.Segment2D
import org.openrndr.shape.ShapeContour
import kotlin.random.Random
open class BezierPatchBase(
val points: List>,
val colors: List> = emptyList()
)
where C : AlgebraicColor, C : ConvertibleToColorRGBa {
init {
require(points.size == 4 && points.all { it.size == 4 })
require(colors.isEmpty() || colors.size == 4 && colors.all { it.size == 4 })
}
/**
* Return a transposed version of the bezier path by transposing the [points] matrix
*/
val transposed
get() = BezierPatchBase(
listOf(
listOf(points[0][0], points[1][0], points[2][0], points[3][0]),
listOf(points[0][1], points[1][1], points[2][1], points[3][1]),
listOf(points[0][2], points[1][2], points[2][2], points[3][2]),
listOf(points[0][3], points[1][3], points[2][3], points[3][3]),
),
if (colors.isEmpty()) emptyList() else {
listOf(
listOf(colors[0][0], colors[1][0], colors[2][0], colors[3][0]),
listOf(colors[0][1], colors[1][1], colors[2][1], colors[3][1]),
listOf(colors[0][2], colors[1][2], colors[2][2], colors[3][2]),
listOf(colors[0][3], colors[1][3], colors[2][3], colors[3][3]),
)
}
)
fun transform(transform: Matrix44) = BezierPatchBase(points.map { r ->
r.map { (transform * it.xy01).div.xy }
}, colors)
private fun coeffs2(t: Double): DoubleArray {
val it = 1.0 - t
val it2 = it * it
val t2 = t * t
return doubleArrayOf(it2, 2 * it * t, t2)
}
private fun coeffs3(t: Double): DoubleArray {
val it = 1.0 - t
val it2 = it * it
val it3 = it2 * it
val t2 = t * t
val t3 = t2 * t
return doubleArrayOf(it3, 3 * it2 * t, 3 * it * t2, t3)
}
/**
* Return a point on the patch by using its u,v parameterization
* @param u a value between 0 and 1
* @param v a value between 0 and 1
*/
fun position(u: Double, v: Double): Vector2 {
val csu = coeffs3(u)
val csv = coeffs3(v)
var result = Vector2.ZERO
for (j in 0 until 4) {
for (i in 0 until 4) {
result += points[j][i] * csu[i] * csv[j]
}
}
return result
}
/**
* Return a gradient vector on the patch by using its u,v parameterization
* @param u a value between 0 and 1
* @param v a value between 0 and 1
*/
fun gradient(u: Double, v: Double): Vector2 {
val f0 = List(4) { MutableList(3) { Vector2.ZERO } }
for (j in 0 until 4) {
for (i in 0 until 3) {
f0[j][i] = points[j][i + 1] - points[j][i]
}
}
val f1 = List(3) { MutableList(3) { Vector2.ZERO } }
for (j in 0 until 3) {
for (i in 0 until 3) {
f1[j][i] = f0[j + 1][i] - f0[j][i]
}
}
val csu = coeffs2(u)
val csv = coeffs2(v)
var result = Vector2.ZERO
for (j in 0 until 3) {
for (i in 0 until 3) {
result += f1[j][i] * csu[i] * csv[j]
}
}
return result
}
/**
* Generate a random point on the path
* @return a point that is uniformly distributed in uv space
*/
fun randomPoint(random: Random = Random.Default) = position(random.nextDouble(), random.nextDouble())
fun horizontal(v: Double): ShapeContour {
val cs = coeffs3(v)
val cps = Array(4) { Vector2.ZERO }
for (j in 0 until 4) {
for (i in 0 until 4) {
cps[j] += points[i][j] * cs[i]
}
}
return ShapeContour(listOf(Segment2D(cps[0], cps[1], cps[2], cps[3])), false)
}
fun vertical(u: Double): ShapeContour {
val cs = coeffs3(u)
val cps = Array(4) { Vector2.ZERO }
for (j in 0 until 4) {
for (i in 0 until 4) {
cps[j] += points[j][i] * cs[i]
}
}
return ShapeContour(listOf(Segment2D(cps[0], cps[1], cps[2], cps[3])), false)
}
/**
* Extract a sub-patch based on uv parameterization
*/
fun sub(u0: Double, v0: Double, u1: Double, v1: Double): BezierPatchBase {
val c0 = Segment2D(points[0][0], points[0][1], points[0][2], points[0][3]).sub(u0, u1)
val c1 = Segment2D(points[1][0], points[1][1], points[1][2], points[1][3]).sub(u0, u1)
val c2 = Segment2D(points[2][0], points[2][1], points[2][2], points[2][3]).sub(u0, u1)
val c3 = Segment2D(points[3][0], points[3][1], points[3][2], points[3][3]).sub(u0, u1)
val sub0 = bezierPatch(c0, c1, c2, c3)
val d0 = Segment2D(sub0.points[0][0], sub0.points[1][0], sub0.points[2][0], sub0.points[3][0]).sub(v0, v1)
val d1 = Segment2D(sub0.points[0][1], sub0.points[1][1], sub0.points[2][1], sub0.points[3][1]).sub(v0, v1)
val d2 = Segment2D(sub0.points[0][2], sub0.points[1][2], sub0.points[2][2], sub0.points[3][2]).sub(v0, v1)
val d3 = Segment2D(sub0.points[0][3], sub0.points[1][3], sub0.points[2][3], sub0.points[3][3]).sub(v0, v1)
return fromSegments(d0, d1, d2, d3).transposed
}
val contour: ShapeContour = ShapeContour(
listOf(
Segment2D(points[0][0], points[0][1], points[0][2], points[0][3]),
Segment2D(points[0][3], points[1][3], points[2][3], points[3][3]),
Segment2D(points[3][3], points[3][2], points[3][1], points[3][0]),
Segment2D(points[3][0], points[2][0], points[1][0], points[0][0]),
), true
)
operator fun times(scale: Double) =
BezierPatchBase(
points.map { j -> j.map { i -> i * scale } },
if (colors.isEmpty()) colors else colors.map { j -> j.map { i -> i * scale } }
)
operator fun div(scale: Double) =
BezierPatchBase(points.map { j -> j.map { i -> i / scale } },
if (colors.isEmpty()) colors else colors.map { j -> j.map { i -> i / scale } }
)
operator fun plus(right: BezierPatchBase) =
BezierPatchBase(List(4) { j -> List(4) { i -> points[j][i] + right.points[j][i] } },
if (colors.isEmpty() && right.colors.isEmpty()) { colors }
else if (colors.isEmpty() && right.colors.isNotEmpty()) { right.colors }
else if (colors.isNotEmpty() && right.colors.isEmpty()) { colors }
else { List(4) { j -> List(4) { i -> colors[j][i] + right.colors[j][i] } } }
)
operator fun minus(right: BezierPatchBase) =
BezierPatchBase(List(4) { j -> List(4) { i -> points[j][i] - right.points[j][i] } },
if (colors.isEmpty() && right.colors.isEmpty()) { colors }
else if (colors.isEmpty() && right.colors.isNotEmpty()) { right.colors }
else if (colors.isNotEmpty() && right.colors.isEmpty()) { colors }
else { List(4) { j -> List(4) { i -> colors[j][i] - right.colors[j][i] } } }
)
fun withColors(colors: List>): BezierPatchBase
where K : AlgebraicColor, K : ConvertibleToColorRGBa {
return BezierPatchBase(points, colors)
}
companion object {
fun fromSegments(c0: Segment2D, c1: Segment2D, c2: Segment2D, c3: Segment2D): BezierPatchBase
where C : AlgebraicColor, C : ConvertibleToColorRGBa {
val c0c = c0.cubic
val c1c = c1.cubic
val c2c = c2.cubic
val c3c = c3.cubic
val c0l = listOf(c0c.start, c0c.control[0], c0c.control[1], c0c.end)
val c1l = listOf(c1c.start, c1c.control[0], c1c.control[1], c1c.end)
val c2l = listOf(c2c.start, c2c.control[0], c2c.control[1], c2c.end)
val c3l = listOf(c3c.start, c3c.control[0], c3c.control[1], c3c.end)
return BezierPatchBase(listOf(c0l, c1l, c2l, c3l))
}
}
}
class BezierPatch(points: List>, colors: List> = emptyList()) :
BezierPatchBase(points, colors)
/**
* Create a cubic bezier patch from 4 segments. The control points of the segments are used in row-wise fashion
*/
fun bezierPatch(c0: Segment2D, c1: Segment2D, c2: Segment2D, c3: Segment2D): BezierPatch {
val c0c = c0.cubic
val c1c = c1.cubic
val c2c = c2.cubic
val c3c = c3.cubic
val c0l = listOf(c0c.start, c0c.control[0], c0c.control[1], c0c.end)
val c1l = listOf(c1c.start, c1c.control[0], c1c.control[1], c1c.end)
val c2l = listOf(c2c.start, c2c.control[0], c2c.control[1], c2c.end)
val c3l = listOf(c3c.start, c3c.control[0], c3c.control[1], c3c.end)
return BezierPatch(listOf(c0l, c1l, c2l, c3l))
}
/**
* Create a bezier patch from a closed shape contour (with 4 segments).
* @param alpha control for linearity, default is `1.0/3.0`
*/
fun bezierPatch(shapeContour: ShapeContour, alpha: Double = 1.0 / 3.0): BezierPatch {
require(shapeContour.segments.size == 4) {
"""contour needs exactly 4 segments (has ${shapeContour.segments.size})"""
}
val c0 = shapeContour.segments[0].cubic
val c1 = shapeContour.segments[1].cubic
val c2 = shapeContour.segments[2].cubic
val c3 = shapeContour.segments[3].cubic
val fa = 1.0 - alpha
val fb = alpha
val x00 = (c0.control[0] * fa + c2.control[1] * fb + c3.control[1] * fa + c1.control[0] * fb) / 2.0
val x01 = (c0.control[1] * fa + c2.control[0] * fb + c3.control[1] * fb + c1.control[0] * fa) / 2.0
val x10 = (c0.control[0] * fb + c2.control[1] * fa + c3.control[0] * fa + c1.control[1] * fb) / 2.0
val x11 = (c0.control[1] * fb + c2.control[0] * fa + c3.control[0] * fb + c1.control[1] * fa) / 2.0
val cps = listOf(
listOf(c0.start, c0.control[0], c0.control[1], c0.end),
listOf(c3.control[1], x00, x01, c1.control[0]),
listOf(c3.control[0], x10, x11, c1.control[1]),
listOf(c2.end, c2.control[1], c2.control[0], c2.start),
)
return BezierPatch(cps)
}
/**
* Create a bezier patch from 4 corners
* @param corners a list of corners from which to create the patch
* @param alpha control for linearity, default is `1.0/3.0`
*/
fun bezierPatch(corners: List, alpha: Double = 1.0 / 3.0): BezierPatch {
require(corners.size == 4) {
"""need exactly 4 corners (got ${corners.size}"""
}
return bezierPatch(ShapeContour.fromPoints(corners, true), alpha)
}
/**
* Distort a shape contour
*/
fun BezierPatch.distort(shapeContour: ShapeContour, referenceRectangle: Rectangle = shapeContour.bounds): ShapeContour {
val distortedSegments = shapeContour.segments.map {
val c = it.cubic
val e = c.end.map(referenceRectangle)
val c0 = c.control[0].map(referenceRectangle)
val c1 = c.control[1].map(referenceRectangle)
val s = c.start.map(referenceRectangle)
val ne = position(e.x, e.y)
val ns = position(s.x, s.y)
val nc0 = position(c0.x, c0.y)
val nc1 = position(c1.x, c1.y)
Segment2D(ns, nc0, nc1, ne)
}
return ShapeContour(distortedSegments, shapeContour.closed, shapeContour.polarity)
}
private fun Vector2.map(rect: Rectangle): Vector2 {
val nx = (x - rect.x) / rect.width
val ny = (y - rect.y) / rect.height
return Vector2(nx, ny)
}
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