My matrix multiplication, used to row a boat.

boats.py

import display, math, time, buttons


def drawBoat():
    display.pushMatrix()
    drawBoatBottom(0x000000)
    display.translate(-4, 0)
    drawBoatMast(0x000000, 0x000000)
    display.popMatrix()


def drawBoatMast(mastColor, flagColor):
    # 0--1
    # |  |
    # |  6
    # |  |\
    # |  5-4
    # |  |
    # 3--2
    x0 = 0
    y0 = -23
    x1 = 3
    y1 = -23
    x2 = 3
    y2 = 0
    x3 = 0
    y3 = 0
    x4 = 12
    y4 = -10
    x5 = 3
    y5 = -10
    x6 = 3
    y6 = -20
    display.drawQuad(x0, y0, x1, y1, x2, y2, x3, y3, mastColor)
    # display.drawLine(x0, y0, x1, y1, 0x000000)
    # display.drawLine(x1, y1, x2, y2, 0x000000)
    # display.drawLine(x2, y2, x3, y3, 0x000000)
    # display.drawLine(x3, y3, x0, y0, 0x000000)
    display.drawTri(x6, y6, x4, y4, x5, y5, flagColor)
    # display.drawLine(x6, y6, x4, y4, 0x000000)
    # display.drawLine(x4, y4, x5, y5, 0x000000)
    # display.drawLine(x4, y4, x6, y6, 0x000000)


def drawBoatBottom(color):
    # 0--------1
    #  \      /
    #   3----2
    x0 = -20
    y0 = 0
    x1 = 20
    y1 = 0
    x2 = 16
    y2 = 8
    x3 = -16
    y3 = 8
    display.drawQuad(x0, y0, x1, y1, x2, y2, x3, y3, color)
    # display.drawLine(x0, y0, x1, y1, 0x000000)
    # display.drawLine(x1, y1, x2, y2, 0x000000)
    # display.drawLine(x2, y2, x3, y3, 0x000000)
    # display.drawLine(x3, y3, x0, y0, 0x000000)


def drawSun(color):
    display.pushMatrix()
    display.translate(-3, -3 - display.height())
    display.drawCircle(0, 0, 30, 0, math.pi * 2, True, color)
    display.rotate(sunOffset)
    for i in range(20):
        display.rotate(math.pi / 10)
        display.drawLine(0, 35, 0, 45, color)
    display.popMatrix()


def btnAEvent(value):
    global boatInWater, boatVelocity, boatY
    if value and boatInWater and boatVelocity == 0:
        boatInWater = False
        boatVelocity = -10
        boatY -= 8


# For good measure.
display.clearMatrix()

display.translate(0, display.height())

sunOffset = 0
offset = 0
boatX = display.width() / 6
boatAngle = 0
boatY = 0
boatInWater = True
boatVelocity = 0

buttons.attach(buttons.BTN_A, btnAEvent)

while True:
    display.drawFill(0xffffff)
    drawSun(0x000000)
    for i in range(display.width()):
        wave = math.sin((i + offset) * math.pi / 35) * 8 - 35
        display.drawPixel(i, wave, 0x000000)
        if i & 1:
            for j in range(round(wave - 1) | 1, 0, 2):
                display.drawPixel(i, j + ((i >> 1) & 1) + 1, 0x000000)
    display.pushMatrix()
    waterLevelAtBoat = math.sin((boatX + offset) * math.pi / 35) * 8 - 35 + boatVelocity
    if boatInWater:
        if boatY > waterLevelAtBoat and boatVelocity < 0:
            boatY += boatVelocity
            boatVelocity -= 2
            if boatY <= waterLevelAtBoat:
                boatY = waterLevelAtBoat
                boatVelocity = 0
        else:
            boatY = waterLevelAtBoat
            boatVelocity = 0
            waterLevelBeforeBoat = math.sin((boatX + 2 + offset) * math.pi / 35) * 8 - 35 + boatVelocity
            boatAngle = math.atan2(waterLevelBeforeBoat - waterLevelAtBoat, 2)
    else:
        boatY += boatVelocity
        boatVelocity = boatVelocity + 3 if boatVelocity < 20 else 20
        if boatY >= waterLevelAtBoat and boatVelocity > 0:
            boatInWater = True
            boatVelocity = -1
            boatY = waterLevelAtBoat
    display.translate(boatX, boatY - 6)
    display.rotate(boatAngle)
    drawBoat()
    display.popMatrix()
    offset += 8
    sunOffset += math.pi * 0.025
    display.flush()