diff --git a/src/graphics/buffers.c b/src/graphics/buffers.c
index 7f65d7a..e922300 100644
--- a/src/graphics/buffers.c
+++ b/src/graphics/buffers.c
@@ -201,6 +201,19 @@ static int compute_arrow_2D(int space_size_x,
     float base = center + (2 * site - 1) * (0.1f / space_size_x);
     float lat = 0.4f / space_size_x;
 
+    /* for (int i = 0; i < space_size_x; i++) */
+    /*     for (int j = 0; j < space_size_y; j++) */
+    /*         for (int k = 0; k < space_size_z; k++) */
+    /* { */
+
+    /*     x = - ((space_size_x % 2) * (space_size_x / 2 - i) */
+    /*         - (space_size_x % 2 - 1) * (i + 0.5f - space_size_x / 2)) / space_size_x * 2 * EDGE; */
+    /*     y = - ((space_size_x % 2) * (space_size_x / 2 - j) */
+    /*         - (space_size_x % 2 - 1) * (j + 0.5f - space_size_x / 2)) / space_size_x * 2 * EDGE; */
+    /*     z = - ((space_size_x % 2) * (space_size_x / 2 - k) */
+    /*         - (space_size_x % 2 - 1) * (k + 0.5f - space_size_x / 2)) / space_size_x * 2 * EDGE; */
+    /* } */
+
     *(vertex_origin + vertex_ndx + 0) = tip;
     *(vertex_origin + vertex_ndx + 1) = zero;
     *(vertex_origin + vertex_ndx + 2) = zero;
diff --git a/src/graphics/graphics.c b/src/graphics/graphics.c
index 40c721b..dde63be 100644
--- a/src/graphics/graphics.c
+++ b/src/graphics/graphics.c
@@ -539,9 +539,9 @@ GLubyte arrows[] = {
 
 static void get_model_data_and_user_preferences(){
 
-    model_space_size_x = 3;    //   2 < model_space_size_x < 32
-    model_space_size_y = 1;    //   2 < model_space_size_y < 32
-    model_space_size_z = 0;    //   2 < model_space_size_z < 32
+    model_space_size_x = 3;    //   1 < model_space_size_x
+    model_space_size_y = 0;    //   1 < model_space_size_y
+    model_space_size_z = 0;    //   1 < model_space_size_z
     model_arrows_nb = 2; //  assert : l'emplacement des flèches est contraint
                          //  par model_space_size_x, y, z et le nombre de sites
 
@@ -584,25 +584,45 @@ static void compute_buffers_sizes(int model_space_size_x,
                                   int pref_style_lines_planes,
                                   int pref_style_mix_colors)
 {
-    int four_ladder_amounts = 8; // 4 parallels to connect the orthogonal squares
-
     buffer_vertex_size = (model_space_size_x + 1)
                        * (model_space_size_y + 1)
-                       * (model_space_size_z + 1);
+                       * (model_space_size_z + 1)
+                       * 3
+                       + model_space_size_x * 3
+                       + model_space_size_y * 3
+                       + model_space_size_z * 3
+                       - 3;
+
     buffer_colors_size = (model_space_size_x + 1)
                        * (model_space_size_y + 1)
-                       * (model_space_size_z + 1);
+                       * (model_space_size_z + 1)
+                       * 3
+                       + model_space_size_x * 3
+                       + model_space_size_y * 3
+                       + model_space_size_z * 3
+                       - 3;
     buffer_plans_size = 0;
     buffer_lines_size  = (model_space_size_x + 1) * 2
                        + (model_space_size_y + 1) * 2
                        + (model_space_size_z + 1) * 2;
 
+    buffer_lines_size  = (model_space_size_x + 1)
+                       * (model_space_size_y + 1)
+                       * (model_space_size_z + 1)
+                       * 3
+                       - model_space_size_x
+                       - model_space_size_y
+                       - model_space_size_z
+                       + 2;  // je suis en 2D
+                                 // pourquoi est-ce possible ?
     buffer_lines_size += 8 * pref_mark_unit_space; // 8 because 4 diagonal lines
 
-    buffer_vertex_size += model_arrows_nb * 15; //  - 2, + 3 ou -8 == Ad Hoc !
+    buffer_vertex_size += model_arrows_nb * 9; // je suis en 2D
+//    buffer_vertex_size += model_arrows_nb * 15 - 3; //  - 2, + 3 ou -8 == Ad Hoc !
     buffer_colors_size += model_arrows_nb * 15;
     buffer_plans_size  += 0;
-    buffer_lines_size  += model_arrows_nb * 16;
+    buffer_lines_size  += model_arrows_nb * 6; // je suis en 2D
+//    buffer_lines_size  += model_arrows_nb * 16;
 
     if (S) printf("allocated buffers sizes  :%4d/3 = %3d vertices, %4d/3 = %3d colors,\
  %4d/2 = %3d lines, %4d/3 = %3d plans.     (space size = %d x %d x %d)\n",\