Code Sketch

// polar bear using pic.thatsXX transforms
// works with Kojo 2.9.18 and later
// uses image E2.png, which is available at:https://drive.google.com/drive/u/1/folders/1vwnFu5JBQpdhNkrewq27w943sQuE3Wtw

def mountain(n: Int) = Picture {
    beginShape()
    curveVertexRt(-300, 0)
    curveVertexRt(-300, 0)
    curveVertexRt(n, 100)
    curveVertexRt(n, 0)
    curveVertexRt(n, 0)
    endShape()
}

def trunk(size: Double) = Picture {
    setPenThickness(15)
    setPenColor(cm.hsl(120, 1.00, 0.07))
    forward(size)
}

def leftbranch(size: Double): Picture = {
    rot(30) -> trunk(size)
}

def rightbranch(size: Double): Picture = {
    rot(-30) -> trunk(size)
}

def tree(size: Double): Picture = {
    setPenColor(cm.hsl(204, 1.00, 0.50))
    picStack(
        trunk(size),
        trans(0, size) -> leftbranch(size),
        trans(0, size) -> rightbranch(size),
    )
}

def lefttree(size: Double): Picture = {
    rot(30) -> tree(size)
}

def righttree(size: Double): Picture = {
    rot(-30) -> tree(size)
}

def finaltree(n: Int, size: Double): Picture = {
    if (n == 1) {
        trunk(size)
    }

    else {
        picStack(
            tree(size - 10),
            trans(42, 162) -> righttree(size),
            trans(-42, 162) -> lefttree(size),
            rot(30) * trans(-5, 348) -> finaltree(n - 1, size - 10),
            rot(-30) * trans(5, 348) -> finaltree(n - 1, size - 10),
            rot(10) * trans(5, 148) -> finaltree(n - 1, size - 10),
            rot(-10) * trans(5, 148) -> finaltree(n - 1, size - 10)
        )
    }
}

def bird(n: Double) = Picture {

    setPenColor(black)
    setPenThickness(4)
    right()
    right(60, n)
    left(120)
    right(60, n)
}

def mountains(n: Int, size: Double): Picture = {

    if (n == 1) {
        mountain(150)
            .withFillColor(mountainclr)
            .withPenColor(noColor)
    }

    else {
        picStack(
            mountain(120)
                .withPenColor(noColor)
                .withFillColor(mountainclr),
            mountains(n - 1, size)
                .thatsTranslated(200, 0)
        )
    }
}

def birds(num: Int, size: Double): Picture = {
    if (num == 1) {
        bird(size)
    }

    else {
        picStack(
            bird(size),
            birds(num - 1, size + 2)
                .thatsTranslated(size * 1.1, size - 5)
        )
    }

}

cleari()
val assetsDir = "~/Pictures"
val bg = Picture.image(s"$assetsDir/E2.png")
val E1 = scale(0.3) -> bg
val finalpic = picStack(
    finaltree(4, 110),
    finaltree(4, 110)
        .withPenThickness(2)
        .thatsTranslated(4, 0)
        .withBlurring(30)
        .withFlippedY
)
val sky = cm.linearGradient(0, 100, cm.hsl(202, 1.00, 0.50), 0, 200, cm.blue, false)
val sunclr = cm.radialGradient(0, 0, cm.hsl(20, 1.00, 0.54), 70, cm.blue, false)
val sunclr2 = cm.radialGradient(0, 0, cm.hsl(20, 1.00, 0.68), 70, ColorMaker.hsl(194, 0.68, 0.56), false)
val mountainclr = cm.linearGradient(-55, 40, ColorMaker.hsl(120, 1.00, 0.38), 0, 0, ColorMaker.hsl(120, 1.00, 0.19), false)
val scenery = picStack(
    Picture.rectangle(850, 380)
        .thatsTranslated(-300, -380)
        .withPenColor(noColor)
        .withFillColor(ColorMaker.hsl(194, 0.68, 0.56)),
    Picture.rectangle(850, 380)
        .thatsTranslated(-300, 0)
        .withPenColor(noColor)
        .withFillColor(sky),
    mountains(3, 10)
        .thatsTranslated(0, -4)
        .withPenColor(noColor)
        .withPenThickness(0)
        .withBlurring(10)
        .withFading(150)
        .withFlippedY,
    Picture.circle(75)
        .withPenColor(noColor)
        .thatsTranslated(0, 239)
        .withFillColor(sunclr2)
        .withFading(220)
        .withFlippedY,
    Picture.circle(75)
        .withPenColor(noColor)
        .thatsTranslated(0, 285)
        .withFillColor(sunclr),
    mountains(3, 10),
    birds(3, 20)
        .thatsTranslated(50, 180),
    trans(-120, 0) * scale(0.13) -> finalpic,
    trans(20, 0) * scale(0.08) -> finalpic,
    trans(220, 0) * scale(0.12) -> finalpic,
    trans(320, 0) * scale(0.07) -> finalpic,
    trans(450, 0) * scale(0.15) -> finalpic,
    E1
        .thatsTranslated(-20, -5),
    E1
        .withFlippedY
        .withBlurring(10)
        .thatsTranslated(-20, -5),
    birds(3, 20)
        .withPenThickness(1.5)
        .withBlurring(8)
        .withFading(90)
        .withFlippedY
        .thatsTranslated(50, -180)
)
drawCentered(scenery)