from pygame import draw, mouse
from .. import HEIGHT, WIDTH
from ..colors import *
from ..math import *

class VecProj:

    title = "Vector Projection"

    def render(self, surface):
        x1 = WIDTH / 4
        y1 = HEIGHT / 2 + 100
        x2 = 0.75 * WIDTH
        y2 = HEIGHT / 2

        cx, cy = mouse.get_pos()

        lx, ly = x2 - x1, y2 - y1           # line vector
        llen = length(lx, ly)
        lnx, lny = lx / llen, ly / llen     # line normal
        lcx, lcy = cx - x1, cy - y1         # line start - cursor vector

        proj = dot(lcx, lcy, lx, ly) / llen

        draw.line(
            surface, GREEN, (cx, cy), add(x1, y1, *scale(lnx, lny, proj)), 5
        )
        draw.line(surface, WHITE, (cx, cy), (x1, y1), 5)
        draw.line(surface, YELLOW, (x1, y1), (x2, y2), 5)