from libs import *

# https://iquilezles.org/articles/intersectors/
def intersect_tri(ro, rd, tv):
    e1 = tv[1] - tv[0]
    e2 = tv[2] - tv[0]
    to = ro - tv[0]
    n = np.cross(e1, e2)
    q = np.cross(to, rd)
    d = 1.0 / np.dot(rd, n)
    u = d * np.dot(-q, e2)
    v = d * np.dot(q, e1)
    t = d * np.dot(-n, to)
    if u > 0.0 and v > 0.0 and u + v < 1.0 and t > 1e-3:
        return t

class Camera:
    def __init__(self, **kwargs):
        self.pos = vec([0, 0, 0])
        self.theta = 0
        self.phi = 0
        self.fovy = kwargs.get("fovy", 90)
        self.aspect = 1

    def looking(self):
        return vec([
            np.cos(self.phi) * np.sin(self.theta),
            np.sin(self.phi),
            np.cos(self.phi) * np.cos(self.theta)
        ])

    def up(self):
        return vec([0, 1, 0])

    def view_mat(self):
        f = normalize(self.looking())
        s = normalize(np.cross(f, self.up()))
        u = np.cross(s, f)
        m = np.identity(4, dtype=FLOAT)
        m[:3, :3] = [s, u, -f]
        m[:3, 3] = [-np.dot(s, self.pos), -np.dot(u, self.pos), np.dot(f, self.pos)]
        return m

    def persp_mat(self):
        near = 0.1
        far = 100
        f = 1.0 / np.tan(np.radians(self.fovy) / 2)
        depth = near - far
        return vec([
            [f / self.aspect, 0, 0, 0],
            [0, f, 0, 0],
            [0, 0, (near + far) / depth, (2 * near * far) / depth],
            [0, 0, -1, 0]
        ])

    def mvp(self, ent):
        if ent.hud:
            am = np.identity(4, dtype=FLOAT)
            am[0, 0] = 1 / self.aspect
            return ent.translate() @ am @ ent.orient
        else:
            return self.persp_mat() @ self.view_mat() @ ent.translate() @ ent.orient

    def draw(self, ent, loc_mvp):
        if not ent.vao:
            ent.build_vao()
        glUniformMatrix4fv(loc_mvp, 1, GL_TRUE, self.mvp(ent))
        glBindVertexArray(ent.vao)
        glDrawArrays(ent.draw_mode, 0, len(ent.verts))

    def target(self, scene):
        l = self.looking()
        d, c, n = None, None, None
        for ent in scene:
            if ent.hud:
                continue
            elif ent.draw_mode == GL_TRIANGLE_STRIP:
                tl = ((i, ent.verts[i:i + 3]) for i in range(len(ent.verts) - 2))
            elif ent.draw_mode == GL_TRIANGLES:
                tl = ((i, ent.verts[3 * i:3 * (i + 1)]) for i in range(len(ent.verts) // 3))
            else:
                raise NotImplementedError
            for (i, t) in tl:
                r = intersect_tri(self.pos, l, np.dot(t, ent.orient[:3, :3].T) + ent.pos)
                if r and (d is None or r < d):
                    d, c, n = r, ent, i
        return c, n