input mp-solid

vardef grillexy(expr aa,bb,cc,dd)=
  save _grillexy;
  picture _grillexy;
  color Fc[][];color G[][];
  for l=aa upto bb:
    for k=cc upto dd:
      G[l][k]=(k,l,0);
    endfor;
  endfor;
  apj:=0;
  for l=aa upto (bb-1):
    for k=cc upto (dd-1):
      apj:=apj+1;
      cpt[apj]:=apj;
      Fc[apj][1]:=G[l][k];
      Fc[apj][2]:=G[l][k+1];
      Fc[apj][3]:=G[l+1][k+1];
      Fc[apj][4]:=G[l+1][k];
      Fc[apj][5]:=(Fc[apj][1]+Fc[apj][2]+Fc[apj][3]+Fc[apj][4])/4;
      ALT[apj]:=-Zpart(GCoord(Fc[apj][1]));
    endfor;
  endfor;
  QS(1,apj);
  _grillexy=image(
    for k=1 upto apj:
      fill for l=1 upto 4:
	Projette(Fc[cpt[k]][l])--
      endfor
      cycle withcolor if arcenciel: Hsvtorgb(((k/apj)[0*360,1*360],0.5,0.5))
	else: couleur fi;
      draw for l=1 upto 4:
	Projette(Fc[cpt[k]][l])--
      endfor
      cycle withpen pencircle scaled0.25bp;
    endfor;
    );
  _grillexy
enddef;

vardef grillexz(expr aa,bb,cc,dd)=
  save _grillexz;
  picture _grillexz;
  color Fc[][];color G[][];
  for l=aa upto bb:
    for k=cc upto dd:
      G[l][k]=(k/10,0,l/10);
    endfor;
  endfor;
  apj:=0;
  for l=aa upto (bb-1):
    for k=cc upto (dd-1):
      apj:=apj+1;
      cpt[apj]:=apj;
      Fc[apj][1]:=G[l][k];
      Fc[apj][2]:=G[l][k+1];
      Fc[apj][3]:=G[l+1][k+1];
      Fc[apj][4]:=G[l+1][k];
      Fc[apj][5]:=(Fc[apj][1]+Fc[apj][2]+Fc[apj][3]+Fc[apj][4])/4;
      ALT[apj]:=-Zpart(GCoord(Fc[apj][1]));
    endfor;
  endfor;
  QS(1,apj);
  _grillexz=image(
    for k=1 upto apj:
      fill for l=1 upto 4:
	Projette(Fc[cpt[k]][l])--
      endfor
      cycle withcolor if arcenciel: Hsvtorgb((180,(cpt[k]/apj)[0,1],(cpt[k]/apj)[0,1]))
	else: couleur fi;
    endfor;
    );
  _grillexz
enddef;

vardef grilleyz(expr aa,bb,cc,dd)=
  save _grilleyz;
  picture _grilleyz;
  color Fc[][];color G[][];
  for l=aa upto bb:
    for k=cc upto dd:
      G[l][k]=(0,k/10,l/10);
    endfor;
  endfor;
  apj:=0;
  for l=aa upto (bb-1):
    for k=cc upto (dd-1):
      apj:=apj+1;
      cpt[apj]:=apj;
      Fc[apj][1]:=G[l][k];
      Fc[apj][2]:=G[l][k+1];
      Fc[apj][3]:=G[l+1][k+1];
      Fc[apj][4]:=G[l+1][k];
      Fc[apj][5]:=(Fc[apj][1]+Fc[apj][2]+Fc[apj][3]+Fc[apj][4])/4;
      ALT[apj]:=-Zpart(GCoord(Fc[apj][1]));
    endfor;
  endfor;
  QS(1,apj);
  _grilleyz=image(
    for k=1 upto apj:
      fill for l=1 upto 4:
	Projette(Fc[cpt[k]][l])--
      endfor
      cycle withcolor if arcenciel: Hsvtorgb((120,(cpt[k]/apj)[0,1],(cpt[k]/apj)[0,1]))
	else: couleur fi;
    endfor;
    );
  _grilleyz
enddef;

vardef grillecirc(expr aa,bb)=
  save _grillecirc;
  picture _grillecirc;
  color Fc[][];color G[][];
  for l=aa step 5 until bb:%upto bb:
    for k=0 upto 10:
      G[l][k]=((k/10)*3*cosd(l),(k/10)*3*sind(-l),2);
    endfor;
  endfor;
  apj:=0;
  for l=aa step 5 until (bb-5):
    for k=0 upto 9:
      apj:=apj+1;
      cpt[apj]:=apj;
      Fc[apj][1]:=G[l][k];
      Fc[apj][2]:=G[l][k+1];
      Fc[apj][3]:=G[l+5][k+1];
      Fc[apj][4]:=G[l+5][k];
      Fc[apj][5]:=(Fc[apj][1]+Fc[apj][2]+Fc[apj][3]+Fc[apj][4])/4;
      ALT[apj]:=-Zpart(GCoord(Fc[apj][1]));
    endfor;
  endfor;
  QS(1,apj);
  _grillecirc=image(
    for k=1 upto apj:
      fill for l=1 upto 4:
	Projette(Fc[cpt[k]][l])--
      endfor
      cycle withcolor if arcenciel: Hsvtorgb((aa+180,(cpt[k]/apj)[0,1],1))
	else: couleur fi;
    endfor;
    );
  _grillecirc
enddef;

vardef tranche(expr aa,bb)=
  save _tranche;
  picture _tranche;
  color Fc[][];color G[][];
  for l=aa step 5 until bb:
    for k=0 upto 10:
      G[l][k]=(3*cosd(l),3*sind(-l),2*k/10);
    endfor;
  endfor;
  apj:=0;
  for l=aa step 5 until (bb-5):
    for k=0 upto 9:
      apj:=apj+1;
      cpt[apj]:=apj;
      Fc[apj][1]:=G[l][k];
      Fc[apj][2]:=G[l][k+1];
      Fc[apj][3]:=G[l+5][k+1];
      Fc[apj][4]:=G[l+5][k];
      Fc[apj][5]:=(Fc[apj][1]+Fc[apj][2]+Fc[apj][3]+Fc[apj][4])/4;
      ALT[apj]:=-Zpart(GCoord(Fc[apj][1]));
    endfor;
  endfor;
  QS(1,apj);
  _tranche=image(
    for k=1 upto apj:
      fill for l=1 upto 4:
	Projette(Fc[cpt[k]][l])--
      endfor
      cycle withcolor if arcenciel: Hsvtorgb((aa+180,1,(cpt[k]/apj)[0,1]))
	else: couleur fi;
    endfor;
    );
  _tranche
enddef;

figureespace(-10u,-10u,10u,10u);
Initialisation(500,45,20,50);
arcenciel:=true;
for k=90 step 5 until 265:
  draw tranche(k,k+5);
endfor;
for k=0 step 5 until 40:
  draw tranche(k,k+5);
endfor;
draw grillexz(0,20,0,30);
draw grilleyz(0,20,0,30);
for k=0 step 5 until 265:
  draw grillecirc(k,k+5);
endfor;
drawarrow Projette((0,0,1))--Projette((0,3,1)) withpen pencircle scaled 2bp;
label.top(btex Saturation etex rotated(angle(Projette((0,3,1))-Projette((0,0,1)))),Projette((0,1.5,1)));
drawarrow Projette((3.2*cosd(240),3.2*sind(-240),0))--Projette((3.2*cosd(240),3.2*sind(-240),2)) withpen pencircle scaled 2bp;
label.rt(btex Valeur etex rotated(angle(Projette((3.2*cosd(240),3.2*sind(-240),0))-Projette((3.2*cosd(240),3.2*sind(-240),2)))),Projette((3.2*cosd(240),3.2*sind(-240),1)));
drawarrow Projette((3.2*cosd(-30),3.2*sind(30),1.8))..Projette(((3.2*cosd(10),3.2*sind(-10),1.8)))..Projette(((3.2*cosd(20),3.2*sind(-20),1.8)))..Projette(((3.2*cosd(30),3.2*sind(-30),1.8))) withpen pencircle scaled 2bp;
label.bot(btex Teinte etex rotated angle(Projette(((3.2*cosd(-30),3.2*sind(30),1.8)))-Projette((3.2*cosd(30),3.2*sind(-30),1.8))),Projette(((3.2*cosd(0),3.2*sind(0),1.8))));
finespace;
end