package bezierpatch

import org.openrndr.application
import org.openrndr.color.ColorRGBa
import org.openrndr.extra.shapes.bezierpatches.bezierPatch
import org.openrndr.shape.Circle

/**
 * Shows how to get positions and gradient values of those positions
 * from a [bezierPatch]
 *
 * You can think of bezierPatch.position() as requesting points
 * in a wavy flag (the bezier patch) using normalized uv coordinates.
 */
fun main() = application {
    configure {
        width = 800
        height = 800
    }
    program {
        val bp = bezierPatch(
            Circle(drawer.bounds.center, 350.0).contour
            //Rectangle.fromCenter(drawer.bounds.center, 550.0).contour
        )

        extend {
            drawer.clear(ColorRGBa.PINK)
            drawer.stroke = ColorRGBa.BLACK

            for (j in 1 until 50 step 2) {
                for (i in 1 until 50 step 2) {
                    val u = i / 50.0
                    val v = j / 50.0
                    val pos = bp.position(u, v)
                    val grad = bp.gradient(u, v).normalized * 10.0
                    val perpendicular = grad.perpendicular()
                    drawer.lineSegment(pos - grad, pos + grad)
                    drawer.lineSegment(pos - perpendicular, pos + perpendicular)
                    //drawer.circle(pos + grad, 3.0)
                }
            }
        }
    }
}