FindContours04.kt

import org.openrndr.application
import org.openrndr.color.ColorRGBa
import org.openrndr.draw.loadImage
import org.openrndr.extra.color.colormatrix.grayscale
import org.openrndr.extra.marchingsquares.findContours
import org.openrndr.math.Vector2
import kotlin.math.PI
import kotlin.math.cos

fun main() = application {
    configure {
        width = 720
        height = 540
    }
    program {
        val image = loadImage("demo-data/images/image-001.png")
        image.shadow.download()
        extend {
            drawer.clear(ColorRGBa.BLACK)
            drawer.stroke = ColorRGBa.BLACK
            drawer.fill = null
            fun f(v: Vector2): Double {
                val iv = v.toInt()
                val d =
                    if (iv.x >= 0 && iv.y >= 0 && iv.x < image.width && iv.y < image.height) image.shadow[iv.x, iv.y].luminance else 0.0
                return cos(d * PI * 8.0 + seconds)
            }

            val contours = findContours(::f, drawer.bounds.offsetEdges(32.0), 4.0)
            drawer.drawStyle.colorMatrix = grayscale()
            drawer.scale(width.toDouble() / image.width, height.toDouble() / image.height)
            drawer.image(image)
            drawer.contours(contours)
        }
    }
}