DemoNPointLinearGradient01.kt

import org.openrndr.application
import org.openrndr.color.ColorXSVa
import org.openrndr.color.rgb
import org.openrndr.extra.color.spaces.toOKLABa
import org.openrndr.extra.shadestyles.NPointLinearGradient
import org.openrndr.extra.shadestyles.NPointLinearGradientOKLab
import org.openrndr.shape.Rectangle
import kotlin.math.pow
import kotlin.math.sin

/**
 * Demonstrate using a multicolor linear gradient.
 * The gradient has 8 static saturated colors.
 * The positions of the colors are first distributed
 * uniformly between 0.0 and 1.0 and then animated towards one of
 * the ends over time using pow() and sin(seconds).
 */
fun main() {
    application {
        program {
            val numPoints = 8
            // Create gradients using two different color spaces
            val gradients = listOf(
                NPointLinearGradient(Array(numPoints) {
                    ColorXSVa(it * 360.0 / numPoints, 1.0, 1.0).toRGBa()
                }),
                // OKLab is better at maintaining luminosity across the gradient
                NPointLinearGradientOKLab(Array(numPoints) {
                    ColorXSVa(it * 360.0 / numPoints, 1.0, 1.0).toRGBa()
                        .toOKLABa()
                })
            )

            extend {
                // The points should be sorted values between 0.0 and 1.0
                val distribution = Array(numPoints) {
                    // uniform distribution
                    // (it / (numPoints - 1.0))

                    // skewed and animated distribution
                    (it / (numPoints - 1.0)).pow(1.0 + 0.5 * sin(seconds))
                }
                drawer.run {
                    clear(rgb(0.2))
                    stroke = rgb(0.35)
                    strokeWeight = 8.0

                    gradients.forEachIndexed { i, gradient ->
                        shadeStyle = gradient
                        gradient.points = distribution

                        gradient.rotation = seconds * 10
                        circle(bounds.position(0.34, 0.29 + 0.44 * i), 110.0)

                        gradient.rotation += 90
                        rectangle(
                            Rectangle.fromCenter(
                                bounds.position(0.655, 0.29 + 0.44 * i), 200.0
                            )
                        )
                    }
                }
            }
        }
    }
}