DemoSpectralBlend01.kt

import org.openrndr.application
import org.openrndr.color.ColorRGBa
import org.openrndr.draw.createEquivalent
import org.openrndr.drawImage
import org.openrndr.extra.fx.blend.BlendSpectral
import org.openrndr.extra.fx.blur.BoxBlur
import org.openrndr.extra.fx.patterns.Checkers
import org.openrndr.math.Vector2
import kotlin.math.sin

fun main() = application {
    configure {
        width = 800
        height = 800
    }
    program {
        val a = drawImage(width, height) {
            drawer.stroke = null
            drawer.fill = ColorRGBa.BLUE
            drawer.circle(drawer.bounds.center - Vector2(100.0, 0.0), drawer.width * 0.25)
        }
        val b = drawImage(width, height) {
            drawer.clear(ColorRGBa.TRANSPARENT)
            drawer.stroke = ColorRGBa.RED
            drawer.strokeWeight = 10.0
            drawer.fill = ColorRGBa.YELLOW.opacify(1.0)
            drawer.circle(drawer.bounds.center + Vector2(100.0, 0.0), drawer.width * 0.25)
        }
        BoxBlur().apply { window = 10 }.apply(b, b)
        val checked = a.createEquivalent()
        Checkers().apply(emptyArray(), checked)

        val mixed = a.createEquivalent()
        val blendSpectral = BlendSpectral()
        extend {
            drawer.image(checked)
            blendSpectral.fill = sin(seconds) * 0.5 + 0.5
            blendSpectral.clip = seconds.mod(4.0) > 2.0
            blendSpectral.apply(a, b, mixed)
            drawer.image(mixed)
        }
    }
}