add rotation, need more tests

.gitignore

@@ -14,4 +14,5 @@ lissajous
 squarmania
 testbed
 rndwlkng
+morecircles
 

Makefile

@@ -7,14 +7,30 @@ all:		testbed
 genplotting.o:	genplotting.f90 Makefile
 	gfortran -Wall -c $< 
 
-testbed:	testbed.f90 Makefile genplotting.o
-	gfortran -Wall $< genplotting.o -o $@
+genp_tests.o:	genp_tests.f90 genplotting.o Makefile
+	gfortran -Wall -c $< 
+
+testbed:	testbed.f90 Makefile genp_tests.o genplotting.o
+	gfortran -Wall $< genplotting.o genp_tests.o -o $@
 
 # -----------------------------------------------
 
 rndwlkng:	rndwlkng.f90 Makefile genplotting.o
 	gfortran -Wall $< genplotting.o -o $@
 
+rndwlkng.png:	rndwlkng Makefile
+	./rndwlkng
+	convert rndwlkng.tga rndwlkng.png
+
+# -----------------------------------------------
+
+morecircles:	morecircles.f90 Makefile genplotting.o
+	gfortran -Wall $< genplotting.o -o $@
+
+morecircles.png:	morecircles Makefile
+	./morecircles
+	convert morecircles.tga morecircles.png
+
 # -----------------------------------------------
 
 starfield:	starfield.f90 Makefile genplotting.o
@@ -22,8 +38,7 @@ starfield:	starfield.f90 Makefile genplotting.o
 
 starfield.png:	starfield Makefile
 	./starfield
-	genplot2 -s 512x512 WS/starfield.scratch WS/a.tga
-	convert WS/a.tga $@
+	convert -verbose WS/a.tga $@
 
 # -----------------------------------------------
 
@@ -52,7 +67,6 @@ spirale:	spirale.f90 Makefile genplotting.o
 
 spirale.png:	spirale Makefile
 	./spirale
-	genplot2 -s 512x512 WS/spirale.scratch WS/a.tga
 	convert WS/a.tga $@
 
 # -----------------------------------------------

docs/usage.md

@@ -7,25 +7,47 @@ who can be installed with the [libtthimage](https://git.tetalab.org/tTh/libtthim
 
 For drawing an *useless graphic*, you have to follow three steps:
 initialize, use and terminating.
+You can look at some [examples](exemples.md) and at a
+[full page](http://maison.tth.netlib.re/dessins/numerique.html)
+off UselessGraphics.
 
 ## Initialize
 
 Call the subroutine `genp_init` with two parameters.
-The first is an integer and must be 0. 
+The first is an integer and must be 0. In the futur, it may be used for
+setting some predefined configurations. 
+ 
 The second is the filename for recording the plottings instructions,
-if this filename is an empty string, *stdout* will be used.
+I'm using the `.scratch` extension for naming this file.
+And if this filename is an empty string, *stdout* will be used, so
+you can pipe the data for post-processing purpose.
+ **Be warned:** if you use this option, don't write anything to the
+unit 6 **!**
 
 ## Use it
 
-- real xa, ya, xb, yb
-- integer color
-- call genp_move(xa, ya)
-- call genp_draw(xa, ya, color)
-- call genp_line(xa, ya, xb, yb, color)
+- `real xa, ya, xb, yb`
+- `integer color`
+- `call genp_move(xa, ya)`
+- `call genp_draw(xa, ya, color)`
+- `call genp_line(xa, ya, xb, yb, color)`
 
 ## Terminator
 
-- call genp_end(0)
+- `call genp_end(0)`
+This procedure end the current plotting, add some *bells* to the *WIP*,
+and close the output file, if an output file was specified.
+
+## Rendering
+
+- `subroutine genp_do_render(srcfile, tgafile, xsize, ysize)`
+
+After doing all that useless computing graphics, you can call
+the render, only if you have given a filename to `genp_init`.
+The render engine that I use can only write Targa file, but
+I'm going to add `PNG` to it output in a near futur.
+
+
 
 
 

genp_tests.f90

@@ -0,0 +1,41 @@
+!
+!           MODULE FOR TESTING THE GENPLOTTING MODULE
+!
+! this crapware is released by tTh under the
+!             DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
+!
+! new Sun May 17 11:21:39 AM UTC 2026
+
+module genp_tests
+  use genplotting
+  implicit none
+  contains
+! ---------------------------------------------------------
+subroutine genp_test_rotation()
+
+  real             :: mat(3, 3)
+  real             :: pta(3), ptb(3)
+  integer                :: pass, i, j
+  
+  write(0, '("*** TEST ROTATION ***")' )
+  do pass=1, 90
+    call genp_set_rotation (real(pass)*0.10)
+    write(0, *) "  * the matrix was : "
+    call genp_get_rot_matrix(mat)
+    do i=1, 3
+      do j=1, 3
+        write (0, '("   ", F8.5)', advance='no') mat(i,j)
+      end do
+      write(0, *)
+    end do
+
+    call genp_move(0.0, 0.0)
+    pta(1) = 11.0   ;   pta(2) = 0.0   ;   pta(3) = 0.0
+    ptb = matmul(mat, pta)
+    write(0, '(" got XY: ", F8.5, " ", F8.5)') ptb(1), ptb(2)
+    call genp_draw(ptb(1), ptb(2), 1+mod(pass, 7))
+  end do   ! pass
+
+end subroutine
+! ---------------------------------------------------------
+end module

genplotting.f90

@@ -11,8 +11,9 @@ module genplotting
   real      ::    xoffset, yoffset, xscale, yscale
   private   ::    xoffset, yoffset, xscale, yscale
 
-  real      ::    rotation
-  private   ::    rotation
+  real      ::    rotation, rotmatrix(3,3)
+  private   ::    rotation, rotmatrix, compute_rot_matrix
+  private   ::    print_rot_matrix
 
   integer   ::    outunit = 6
   private   ::    outunit
@@ -21,7 +22,7 @@ contains
 ! ---------------------------------------------------------
 ! the first parameter _must_ be 0.
 ! the second can be
-!    - the name of a file for recoding plot instructions
+!    - the name of a file for recording plot instructions
 !  or
 !    - an empty string for send plot command to stdout
 !
@@ -43,7 +44,8 @@ subroutine genp_init (foo, fname)
   xmin = 9e9       ;       xmax = -9e9
   ymin = 9e9       ;       ymax = -9e9
   xoffset = 0.0    ;       yoffset = 0.0
-  xscale  = 0.0    ;       yscale  = 0.0
+  xscale  = 1.0    ;       yscale  = 1.0
+
   rotation = 0.0
 
 end subroutine
@@ -57,10 +59,71 @@ subroutine genp_get_offset(ox, oy)
   ox = xoffset      ;      oy = yoffset
 end subroutine
 ! ---------------------------------------------------------
+! new Tue May 12 06:51:57 PM UTC 2026
+subroutine genp_set_scale(sx, sy)
+  real, intent(in)     :: sx, sy
+  xscale = sx      ;      yscale = sy
+end subroutine
+subroutine genp_get_scale(sx, sy)
+  real, intent(out)     :: sx, sy
+  sx = xscale      ;      sy = yscale
+end subroutine
+! ---------------------------------------------------------
+! this is a private procedure, don't call it from your prog
+subroutine compute_rot_matrix(angle)
+  real, intent(in)    :: angle
+  write (0, '("compute rot matrix for", F8.5, " radians")') &
+                                     angle
+  rotmatrix (1, 1) =  cos(angle)
+  rotmatrix (1, 2) =  sin(angle)
+  rotmatrix (1, 3) =  0.0
+
+  rotmatrix (2, 1) = -sin(angle)
+  rotmatrix (2, 2) =  cos(angle)
+  rotmatrix (2, 3) =  0.0
+
+  rotmatrix (3, 1) =  0.0
+  rotmatrix (3, 2) =  0.0
+  rotmatrix (3, 3) =  1.0
+
+end subroutine
+!                  -----------------
+!    we have computed some fancy numbers
+!                      and we want to see them !
+subroutine print_rot_matrix(fd)
+  integer, intent(in)    :: fd
+
+  integer                :: i, j
+  do i=1, 3
+    do j=1, 3
+      write (fd, '("   ", F8.5)', advance='no') rotmatrix(i,j)
+    end do
+    write(fd, *)
+  end do
+end subroutine
+! ---------------------------------------------------------
+subroutine genp_set_rotation(angle)
+  real, intent(in)     :: angle
+  rotation = angle
+  !       compute the matrix here !
+  call compute_rot_matrix(angle)
+  ! call print_rot_matrix(0)
+end subroutine
+
+real function genp_get_rotation()
+  genp_get_rotation = rotation
+end function
+
+subroutine genp_get_rot_matrix (dst)
+  real, intent(out)   :: dst(3, 3)
+  dst = rotmatrix
+end subroutine
+! ---------------------------------------------------------
 subroutine genp_move (px, py)
   real, intent(in)        :: px, py
   real                    :: lx, ly
-  lx = px + xoffset     ;     ly = py + yoffset
+  lx = (px*xscale) + xoffset
+  ly = (py*yscale) + yoffset
   write (outunit, '(2F12.5, I5)') lx, ly, -1
   if (lx .lt. xmin)      xmin = lx
   if (lx .gt. xmax)      xmax = lx
@@ -72,7 +135,8 @@ subroutine genp_draw (px, py, color)
   real, intent(in)        :: px, py
   integer, intent(in)     :: color
   real                    :: lx, ly
-  lx = px + xoffset     ;     ly = py + yoffset
+  lx = (px*xscale) + xoffset
+  ly = (py*yscale) + yoffset
   write (outunit, '(2F12.5, I5)') lx, ly, color
   if (lx .lt. xmin)      xmin = lx
   if (lx .gt. xmax)      xmax = lx
@@ -95,10 +159,38 @@ subroutine genp_plot_axes(amp)
   call genp_draw( amp, 0.0, 7)
 end subroutine
 ! ---------------------------------------------------------
+subroutine genp_circle(radius, steps, color)
+  real, intent(in)      :: radius
+  integer, intent(in)   :: steps, color
+
+  integer               :: idx
+  real                  :: fk, ang, x, y
+  logical               :: firstdot
+
+  if (steps .LT.3 ) then
+    write(0, '("circle: steps ", I3, " bad value")') steps
+    return
+  endif
+
+  firstdot = .TRUE.
+  do idx=0, steps
+    fk = real(idx) / real(steps)
+    ang = 6.283185307 * fk
+    ! write(0, '(I5, "  ->  ", 2F10.5)') idx, fk, ang
+    x = radius * cos(ang)   ;   y = radius * sin(ang)
+    if (firstdot) then
+      call genp_move(x, y)   ;    firstdot = .FALSE.
+    else
+      call genp_draw(x, y, color)
+    endif
+  enddo
+
+end subroutine
+! ---------------------------------------------------------
 subroutine genp_end (foo)
   integer, intent(in)    :: foo
 
-  write (0, '("--- genp_end ---")')
+  write (0, '("------------- genp_end -------------")')
   write (0, '("minmax X ", 2F18.5)') xmin, xmax
   write (0, '("minmax Y ", 2F18.5)') ymin, ymax
 

morecircles.f90

@@ -0,0 +1,28 @@
+!
+!           YOU LIKE CIRCLES ? TAKE IT SISTA !
+!
+! this crapware is released by tTh under the
+!             DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
+!
+
+program morecircles
+  use genplotting
+  implicit none
+  integer     idx
+  real        fdx, xp, yp, scx, scy
+  call genp_init(0, "WS/morecircles.scratch")
+  scx = 0.6   ;   scy = 2.3
+  do idx=5, 60
+    fdx = real(idx)
+    xp = 3.5 * cos((fdx/14.0)-0.7)
+    yp = 3.5 * sin((fdx/10.0)+0.3)
+    call genp_set_offset(xp, yp)
+    call genp_set_scale(scx, scy)
+    call genp_circle(fdx, 60, 1+mod(idx, 3))
+    scx = scx + 0.0185
+    scy = scy - 0.0129
+  enddo
+  call genp_end(0)
+  call genp_do_render("WS/morecircles.scratch", "morecircles.tga", &
+                   512, 512)
+end program

rndwlkng.f90

@@ -11,27 +11,24 @@ program rndwlkng
   implicit none
 
   type walker
-    real    :: xloc, yloc
+    real    :: xloc, yloc      ! where I am ?
     real    :: heading         ! direction in degrees
-    real    :: powa
+    real    :: powa            ! correlated to nothing
   end type walker
 
   type (walker)  drunky
   integer        pass
 
-  drunky%xloc     =  0.00
-  drunky%yloc     =  0.00
-  drunky%heading  = 13.37
-  drunky%powa     =  4.00
+  call srand(time())
 
   call genp_init(0, "WS/rndwlkng.scratch")
 
-  do pass=1, 100
+  do pass=1, 73
     drunky%xloc     =  5555 * (rand(0) - 0.50)
     drunky%yloc     =  5555 * (rand(0) - 0.50)
-    drunky%heading  = 13.37
-    drunky%powa     =  4.00
-    call move_the_walker(drunky, 1000, mod(pass, 5)+1)
+    drunky%heading  =   360 * rand(0)
+    drunky%powa     =  6.00
+    call move_the_walker(drunky, 700, mod(pass, 6)+1)
   end do
 
   call genp_end(0)
@@ -47,18 +44,15 @@ subroutine move_the_walker(bob, nbmove, col)
   real                          :: rad, mv, dx, dy
 
   call genp_move(bob%xloc, bob%yloc)
-
   do idx=1, nbmove
     rad = ( 3.141592654 * bob%heading ) / 180.0
-    mv = 0.5 + (bob%powa * rand(0))
+    mv = 1.555 + (bob%powa * rand(0))
     dx = mv * sin(rad)
     dy = mv * cos(rad)   
     bob%xloc = bob%xloc + dx    
     bob%yloc = bob%yloc + dy    
-    bob%heading = bob%heading + 33 * (rand(0) - 0.50000)
-
+    bob%heading = bob%heading + 42.42 * (rand(0) - 0.50000)
     call genp_draw(bob%xloc, bob%yloc, col)
-
   enddo
 
 end subroutine

spirale.f90

@@ -9,12 +9,15 @@ program spirale
   use genplotting
   implicit none
 
+  character(*), parameter :: scratch = "WS/spirale.scratch"
+
   write (0, '(A)') "----[ genplotting spirale ]----"
 
-  call genp_init (0, 'WS/spirale.scratch')
-  call do_spirale (1337, 0.51, 0.0666, 0.7, 3)
+  call genp_init (0, scratch)
+  call do_spirale (1337, 0.51, 0.0666, 0.7, 5)
   call do_spirale (1337, 0.42, 0.0333, 0.7, 6)
   call genp_end (0)
+  call genp_do_render(scratch, "WS/a.tga", 512, 512)
 
 contains
 ! ---------------------------------------------------------

starfield.f90

@@ -7,10 +7,15 @@
 program starfield
   use genplotting
   implicit none
+
+  character(*), parameter :: scratch = "WS/starfield.scratch"
+
   write (0, '(A)') "----[ genplotting starfield ]----"
-  call genp_init (0, 'WS/starfield.scratch')
-  call do_starfield (200)
+  call genp_init (0, scratch)
+  call do_starfield (300)
   call genp_end (0)
+  call genp_do_render(scratch, "WS/a.tga", 512, 512)
+
 contains
 ! ---------------------------------------------------------
 subroutine plot_a_star(at_x, at_y, sz, color)
@@ -20,7 +25,7 @@ subroutine plot_a_star(at_x, at_y, sz, color)
   integer                 :: idx
   real                    :: rad, xv, yv
 
-  write(0, '("plot a star ", 2F8.3)') at_x, at_y
+  write(0, '("plot a star at ", 2F8.3)') at_x, at_y
   call genp_set_offset(at_x, at_y)
   do idx=0, 360, 36
     !   convert index to radians

testbed.f90

@@ -1,10 +1,18 @@
+!
+!           TESTBED FOR GENPLOTTING90
+!
+! this crapware is released by tTh under the
+!             DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
+!
+
 program testbed
   use genplotting
+  use genp_tests
   implicit none
 
   call genp_init(0, "foo.scratch")
-  call genp_plot_axes(13.37)
+  call genp_test_rotation()
+  ! call genp_plot_axes(5.1)
   call genp_end(0)
-  call genp_do_render("foo.scratch", "foo.tga", 512, 512)
 
 end program