import struct, math, numpy as np
from PIL import Image
data=open("content/VIDEO/GEO/BLX_COP.BGF","rb").read()
verts=[]; faces=[]
def addpoly(idx,b):
    for k in range(1,len(idx)-1): faces.append((b+idx[0],b+idx[k],b+idx[k+1]))
curbase=[0]
def parse(p,end):
    while p+3<=end:
        tw=struct.unpack_from("<H",data,p)[0]; p+=2
        cid=tw&0x2fff; lw=4 if(tw&0x8000)else(2 if(tw&0x4000)else 1)
        if p+lw>end:return
        ln=data[p] if lw==1 else(struct.unpack_from("<H",data,p)[0] if lw==2 else struct.unpack_from("<I",data,p)[0])
        p+=lw
        if p+ln>end:return
        if cid==0x88:
            curbase[0]=len(verts)
            for i in range(ln//20):
                o=p+i*20; x,y,z=struct.unpack_from("<fff",data,o); verts.append((x,y,z))
        elif cid==0x47:
            n=ln//4; idx=[struct.unpack_from("<I",data,p+i*4)[0] for i in range(n)]
            for f in range(0,(n//3)*3,3): faces.append((curbase[0]+idx[f],curbase[0]+idx[f+1],curbase[0]+idx[f+2]))
        elif cid==0x4d:
            if ln>=1:
                ppf=data[p]; n=(ln-1)//4
                idx=[struct.unpack_from("<I",data,p+1+i*4)[0] for i in range(n)]
                for f in range(0,(n//ppf)*ppf,ppf): addpoly([idx[f+j] for j in range(ppf)],curbase[0])
        if cid in {0x3,0x70,0x40,0x41,0x42,0x46,0x48,0x10,0x20,0x30}: parse(p,p+ln)
        p+=ln
        if cid==0x5:break
parse(8,len(data))
V=np.array(verts,dtype=float)

def cover(eye,look,fov=95,W=360,H=280):
    eye=np.array(eye,float); fwd=np.array(look,float)-eye; fwd/=np.linalg.norm(fwd)
    up=np.array([0,1,0.0]); right=np.cross(fwd,up); right/=np.linalg.norm(right); upv=np.cross(right,fwd)
    f=(H/2)/math.tan(math.radians(fov)/2); img=np.zeros((H,W))
    for (a,b,c) in faces:
        tri=V[[a,b,c]]
        cam=[(np.dot(pt-eye,right),np.dot(pt-eye,upv),np.dot(pt-eye,fwd)) for pt in tri]
        if any(cz<=0.03 for _,_,cz in cam):continue
        pts=[(W/2+f*cx/cz,H/2-f*cy/cz) for cx,cy,cz in cam]
        xs=[p[0] for p in pts];ys=[p[1] for p in pts]
        mnx=max(int(min(xs)),0);mxx=min(int(max(xs))+1,W-1);mny=max(int(min(ys)),0);mxy=min(int(max(ys))+1,H-1)
        if mnx>=mxx or mny>=mxy:continue
        (x0,y0),(x1,y1),(x2,y2)=pts
        den=((y1-y2)*(x0-x2)+(x2-x1)*(y0-y2))
        if abs(den)<1e-9:continue
        ys2,xs2=np.mgrid[mny:mxy+1,mnx:mxx+1];xf=xs2+.5;yf=ys2+.5
        l0=((y1-y2)*(xf-x2)+(x2-x1)*(yf-y2))/den;l1=((y2-y0)*(xf-x2)+(x0-x2)*(yf-y2))/den;l2=1-l0-l1
        m=(l0>=0)&(l1>=0)&(l2>=0)
        img[ys2[m],xs2[m]]=1
    return (img*255).astype(np.uint8)
# eye near origin (rear), try forward -Z and +Z, and from just inside each end
tiles=[]
for name,eye,look in (("O->-Z",(0,-0.3,0),(0,-0.3,-4)),("O->+Z",(0,-0.3,0),(0,-0.3,4)),
                       ("rear-Z",(0,-0.3,-0.9),(0,-0.3,-4)),("rear+Z",(0,-0.3,-3.7),(0,-0.3,-1))):
    c=cover(eye,look); tiles.append(np.stack([c,c,c],axis=-1))
Image.fromarray(np.concatenate(tiles,axis=1)).save("scratchpad/cop_cover.png")
print("saved cop_cover.png [O->-Z | O->+Z | rear-Z | rear+Z]  (white=covered by a face, black=open)")