From e80bdd0ad53ee9e8e1addf72f8d1b73874b0e88d Mon Sep 17 00:00:00 2001
From: Tonton Th <tth@linda.buvette.org>
Date: Tue, 2 Jun 2026 14:37:14 +0200
Subject: [PATCH] progress on transformation matrix

---
 genp_tests.f90  |  7 ++-----
 genplotting.f90 | 21 +++++++++++++++++++++
 testbed.f90     |  1 -
 3 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/genp_tests.f90 b/genp_tests.f90
index 84fd313..75b73a3 100644
--- a/genp_tests.f90
+++ b/genp_tests.f90
@@ -22,6 +22,7 @@ subroutine genp_test_rotation()
     call genp_set_rotation (real(pass)*0.10)
     write(0, *) "  * the matrix was : "
     call genp_get_rot_matrix(mat)
+    ! display the rotation matrix
     do i=1, 3
       do j=1, 3
         write (0, '("   ", F8.5)', advance='no') mat(i,j)
@@ -29,13 +30,9 @@ subroutine genp_test_rotation()
       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
diff --git a/genplotting.f90 b/genplotting.f90
index 753072a..b23c768 100644
--- a/genplotting.f90
+++ b/genplotting.f90
@@ -122,6 +122,11 @@ end subroutine
 subroutine genp_move (px, py)
   real, intent(in)        :: px, py
   real                    :: lx, ly
+  real                    :: pt(3)
+
+! ====== insert rotation here ?
+  pt(1) = px  ;  pt(2) = py  ;  pt(3) = 0.0
+
   lx = (px*xscale) + xoffset
   ly = (py*yscale) + yoffset
   write (outunit, '(2F12.5, I5)') lx, ly, -1
@@ -135,6 +140,9 @@ subroutine genp_draw (px, py, color)
   real, intent(in)        :: px, py
   integer, intent(in)     :: color
   real                    :: lx, ly
+
+! ====== insert rotation here ?
+
   lx = (px*xscale) + xoffset
   ly = (py*yscale) + yoffset
   write (outunit, '(2F12.5, I5)') lx, ly, color
@@ -187,6 +195,18 @@ subroutine genp_circle(radius, steps, color)
 
 end subroutine
 ! ---------------------------------------------------------
+!    draw a square centered on 0,0
+subroutine genp_square (amp, color)
+  real, intent(in)     :: amp
+  integer, intent(in)  :: color
+  real                 :: ha
+  ha = amp / 2.0
+  call genp_move(-ha, -ha)
+  call genp_draw(-ha,  ha, color)
+  call genp_draw( ha,  ha, color)
+  call genp_draw( ha, -ha, color)
+end subroutine
+! ---------------------------------------------------------
 subroutine genp_end (foo)
   integer, intent(in)    :: foo
 
@@ -194,6 +214,7 @@ subroutine genp_end (foo)
   write (0, '("minmax X ", 2F18.5)') xmin, xmax
   write (0, '("minmax Y ", 2F18.5)') ymin, ymax
 
+  !          XXX   NASTY BUG HERE !
   write (outunit, '(2F18.5, I6)') xmin*1.05, ymin*1.05, -1
   write (outunit, '(2F18.5, I6)') xmin*1.05, ymax*1.05,  0
   write (outunit, '(2F18.5, I6)') xmax*1.05, ymax*1.05,  0
diff --git a/testbed.f90 b/testbed.f90
index 4d7b43d..2c93bfa 100644
--- a/testbed.f90
+++ b/testbed.f90
@@ -12,7 +12,6 @@ program testbed
 
   call genp_init(0, "foo.scratch")
   call genp_test_rotation()
-  ! call genp_plot_axes(5.1)
   call genp_end(0)
 
 end program