+ lissajous plotter

.gitignore

@@ -10,3 +10,5 @@ spirale
 starfield
 randomwalk
 oscilloscope
+lissajous
+

Makefile

@@ -47,3 +47,13 @@ spirale.png:	spirale Makefile
 	convert a.tga $@
 
 # -----------------------------------------------
+
+lissajous:	lissajous.f90 Makefile genplotting.o
+	gfortran -Wall $< genplotting.o -o $@
+
+lissajous.png:	lissajous Makefile
+	./lissajous
+	genplot2 -s 512x512 WS/lissajous.scratch a.tga
+	convert a.tga $@
+
+# -----------------------------------------------

lissajous.f90

@@ -0,0 +1,41 @@
+program sinwaves
+  use genplotting
+  implicit none
+
+  integer  foo, c
+  real     phase
+  call genp_init (0, 'WS/lissajous.scratch')
+
+  do foo=1, 22
+    phase = real(foo) * 0.314159
+    c = 3 + mod(foo, 2)
+    call do_lissajous (2000, phase, c)
+  enddo
+
+  call genp_end (0)
+
+contains
+! ---------------------------------------------------------
+subroutine do_lissajous (nbpass, phy, col)
+  integer, intent(in)   :: nbpass, col
+  real,    intent(in)   :: phy
+
+  integer               :: idx
+  real                  :: ridx, x, y
+
+  do idx=0, nbpass
+    ridx = 6.28318 * (real(idx) / real(nbpass))
+    x = sin(ridx*7 + phy)
+    y = cos(ridx*3)
+
+    if (idx .eq. 0) then
+      call genp_move(x, y)
+    else
+      call genp_draw(x, y, col)
+    endif
+
+  enddo
+
+end subroutine
+! ---------------------------------------------------------
+end program