diff --git a/src/graphics/graphics_control.c b/src/graphics/graphics_control.c
index 57c4e35..384c506 100644
--- a/src/graphics/graphics_control.c
+++ b/src/graphics/graphics_control.c
@@ -562,9 +562,9 @@ static void get_model_data_and_user_preferences(){
     state_size = 8; //   2 < state_size < 32
     arrows_nb = 4; //  assert : leur emplacement doit être fonction de state_size
 
-    pref_3D_xor_2D_space = 0; // default view == 0 == 3D
-    pref_3D_xor_2D_arrows = 1; // default view == 0 == 3D
-    pref_mark_unit_space_zero = 0; // default == 0 == no mark
+    pref_3D_xor_2D_space = 0;       // default == 0 == 3D
+    pref_3D_xor_2D_arrows = 1;      // default == 0 == 3D
+    pref_mark_unit_space_zero = 1;  // default == 0 == no mark
 }
 
 static void compute_vertex_colors_lines_plans_nb(int dim,
@@ -635,6 +635,7 @@ void graphics_init_buffers(const void *gl_area)
                                                vertex_base, color_base,
                                                line_ndx,
                                                pref_mark_unit_space_zero, dgap);
+
     else                      compute_space_3D(state_size,
                                                vertex_base, color_base,
                                                line_ndx,
@@ -722,7 +723,7 @@ void graphics_draw(const void *gl_area)
     /* Use our shaders */
     glUseProgram(entry->program);
 
-    glClearColor(0.3f, 0, 0, 0.8f);
+    glClearColor(0, 0, 0, 0.2f); // glClearColor(0.3f, 0, 0, 0.8f);
     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
     /* Update the "mvp" matrix we use in the shader */
diff --git a/src/graphics/space_3D.c b/src/graphics/space_3D.c
index bfd3c0a..10b1b33 100644
--- a/src/graphics/space_3D.c
+++ b/src/graphics/space_3D.c
@@ -62,21 +62,23 @@ bool compute_space_3D(int state_size,
         *(vertex_base + k * 12 + 10) = - 1.0f / state_size;
         *(vertex_base + k * 12 + 11) = 1.0f / state_size;
 
-        *(color_base  + k * 12 + 0) = 0.8f;
-        *(color_base  + k * 12 + 1) = 0.8f;
-        *(color_base  + k * 12 + 2) = 0.8f;
+        *(color_base  + k * 12 + 0) = 1 - (k / state_size);
+        *(color_base  + k * 12 + 1) = 0.2f;
+        *(color_base  + k * 12 + 2) = (k / state_size);
 
         *(color_base  + k * 12 + 3) = 0.8f;
         *(color_base  + k * 12 + 4) = 0.8f;
-        *(color_base  + k * 12 + 5) = 0.8f;
+        *(color_base  + k * 12 + 5) = 0.2f;
 
         *(color_base  + k * 12 + 6) = 0.8f;
-        *(color_base  + k * 12 + 7) = 0.8f;
-        *(color_base  + k * 12 + 8) = 0.8f;
+        *(color_base  + k * 12 + 7) = (k / state_size);
+        *(color_base  + k * 12 + 8) = 0.2f;
 
-        *(color_base  + k * 12 + 9) = 0.8f;
-        *(color_base  + k * 12 + 10) = 0.8f;
-        *(color_base  + k * 12 + 11) = 0.8f;
+        *(color_base  + k * 12 + 9) = 1 - (k / state_size);
+        *(color_base  + k * 12 + 10) = 0.2f;
+        *(color_base  + k * 12 + 11) = 0.9f;
+
+     //   if (k == 0) for (int j = 0; j < 12; j++) *(color_base + j) = 0.2f;
 
 /*   0.8,  0.8,  0.8,    //  blanc */
 /*   0.8,  0.8,  0.2,    //  jaune */