diff --git a/src/graphics/graphics.c b/src/graphics/graphics.c
index e1d7089..50193d3 100644
--- a/src/graphics/graphics.c
+++ b/src/graphics/graphics.c
@@ -177,6 +177,9 @@ void graphics_write_line (GLuint a, GLuint b)
     buffer_lines_origin[buffer_lines_size + 0] = a;
     buffer_lines_origin[buffer_lines_size + 1] = b;
 
+    if (1) printf("In graphics_write_line() buffer_lines_size = %2d > %2d\n",\
+                  buffer_lines_size, buffer_lines_size + 2);
+
     buffer_lines_size += 2;
 }
 
@@ -683,8 +686,8 @@ void  __attribute__((optimize("no-unroll-loops"))) main_test_graphics (void)
 
     int arbitrary = 3;
     int space_X = 2,// + rand() % arbitrary,
-        space_Y = 2,// + rand() % arbitrary,
-        space_Z = 2;// + rand() % arbitrary;
+        space_Y = 1,// + rand() % arbitrary,
+        space_Z = 1;// + rand() % arbitrary;
     int density_max = space_X * space_Y * space_Z;
     int max = fmax(space_X, space_Y); max = fmax(max, space_Z);
 
@@ -735,15 +738,15 @@ void  __attribute__((optimize("no-unroll-loops"))) main_test_graphics (void)
 
     if (1) printf("buffer_vertex_size before writing_space_ridges_vertex : %d (x 3 = %d)\n", buffer_vertex_size, buffer_vertex_size * 3);
 
-    buffer_vertex_size += write_space_ridges_vertex (buffer_vertex_size, space_X, space_Y, space_Z);
-    buffer_colors_size = buffer_vertex_size;
+    write_space_ridges_vertex (buffer_vertex_size, space_X, space_Y, space_Z);
+    /* buffer_colors_size = buffer_vertex_size; */
 
     if (1) printf("buffer_vertex_size after writing_space_ridges_vertex : %d (x 3 = %d)\n\n", buffer_vertex_size, buffer_vertex_size * 3);
 
-    /* buffer_vertex_size += write_grids_on_space_faces_vertex (space_X, space_Y, space_Z); */
+    write_grids_on_space_faces_vertex (space_X, space_Y, space_Z);
     /* buffer_colors_size = buffer_vertex_size; */
 
-    /* if (1) printf("buffer_vertex_size after writing_space_faces_vertex = %4d - 8 = %3d (x 3 = %4d)\n\n", buffer_vertex_size, buffer_vertex_size - 8, (buffer_vertex_size - 8) * 3); */
+    if (1) printf("buffer_vertex_size after writing_space_faces_vertex = %4d - 8 = %3d (x 3 = %4d)\n\n", buffer_vertex_size, buffer_vertex_size - 8, (buffer_vertex_size - 8) * 3);
     /* if (0) printf("(space_X - 1) * 4 + (space_Y - 1) * 4 + (space_Z - 1) * 4 = %3d (x 3 = %4d)\n\n",\ */
     /*        (space_X - 1) * 4 + (space_Y - 1) * 4 + (space_Z - 1) * 4, ((space_X - 1) * 4 + (space_Y - 1) * 4 + (space_Z - 1)  * 4) * 3); */
 
@@ -774,15 +777,17 @@ void  __attribute__((optimize("no-unroll-loops"))) main_test_graphics (void)
 
     /*   S P A C E    */
 
-    printf("Un problème, là : D'où vient l'accroissement inattendu de buffer_vertex_size ?\n\
-    write_space_ridges_vertex() renvoie 8;  write_space_ridges_lines() renvoie 12\n");
-    buffer_vertex_size += write_space_ridges_lines ();
-    if (1) printf("buffer_vertex_size after writing_space_ridges_lines : %d (x 3 = %d)\n\n", buffer_vertex_size, buffer_vertex_size * 3);
+    if (1) printf("buffer_lines_size before writing 12 space_ridges_lines : %d (x 2 = %d)\n", buffer_lines_size, buffer_lines_size * 2);
+    write_space_ridges_lines ();
+    if (1) printf("buffer_lines_size after writing 12 space_ridges_lines : %d (x 2 = %d)\n\n", buffer_lines_size, buffer_lines_size * 2);
 
-    /* int offset_test = 14; // 10 */
-    /*                       // */
-    /* buffer_vertex_size += write_grids_on_space_faces_lines (offset_test, space_X, space_Y, space_Z); */
-    /* if (1) printf("buffer_vertex_size after writing_space_faces_lines : %d (x 3 = %d)\n\n", buffer_vertex_size, buffer_vertex_size * 3); */
+    if (1) printf("buffer_lines_size before writing_space_faces_lines : %d (x 2 = %d)\n", buffer_lines_size, buffer_lines_size * 2);
+    /* write_grids_on_space_faces_lines (buffer_lines_size, space_X, space_Y, space_Z); */
+    graphics_write_line (8,  9);
+    graphics_write_line (9,  10);
+    graphics_write_line (10,  11);
+    graphics_write_line (11,  8);
+    if (1) printf("buffer_lines_size after writing_space_faces_lines : %d (x 2 = %d)\n\n", buffer_lines_size, buffer_lines_size * 2);
 
     /*  A R R O W S  */
 
diff --git a/src/graphics/grid.c b/src/graphics/grid.c
index 1bb01a7..e23a5fa 100644
--- a/src/graphics/grid.c
+++ b/src/graphics/grid.c
@@ -70,7 +70,7 @@ long write_grids_on_space_faces_vertex (long x, long y, long z)
 {
     float i, max = fmax(x, y); max = fmax(max, z);
 
-    for (i = 0; i < x; i++) {
+    for (i = 1; i < x; i++) {
 
         graphics_write_vertex ((2 * i / x - 1) * x / max, - y / max, - z / max);
         graphics_write_vertex ((2 * i / x - 1) * x / max, - y / max,   z / max);