diff --git a/gui/widgets.py b/gui/widgets.py
index ec76c70..af629fa 100644
--- a/gui/widgets.py
+++ b/gui/widgets.py
@@ -109,11 +109,31 @@ def action_rect(self):
         self.__gl_scene().create_rect()
 
     def action_stress_test2(self):
+        def set1(u, v):
+            x = glm.sinh(u) * glm.cosh(v)
+            y = glm.sinh(v)
+            z = glm.cosh(u) * glm.cosh(v)
+            return glm.vec3(x, y, z)
+
+        def set2(u, v):
+            x = u
+            y = v
+            z = glm.sin(2 * (x + y * y * y))
+            return glm.vec3(x, y, z)
+
+        def set3(u, v):
+            x = u
+            y = v
+            z = (1 - x * x / 100 - y * y / 100) ** 0.5
+            return glm.vec3(x, y, z.real)
+
         scene = self.__gl_scene().get_scene()
-        bounds = 4
-        step = 0.05
+        bounds = 10
+        step = 0.2
         max_buffer_size = 10_000
 
+        func = random.choice([set1, set2, set3])
+
         prev = None
         objects = []
         u = -bounds
@@ -121,10 +141,7 @@ def action_stress_test2(self):
             v = -bounds
             while v < bounds:
                 v += step
-                x = glm.sinh(u) * glm.cosh(v)
-                y = glm.sinh(v)
-                z = glm.cosh(u) * glm.cosh(v)
-                pos = glm.vec3(x, y, z)
+                pos = func(u, v)
                 point = ScenePoint.by_pos(pos)
                 objects.append(point)
 
diff --git a/scene/render_geometry.py b/scene/render_geometry.py
index 4caf9f2..c1a11f3 100644
--- a/scene/render_geometry.py
+++ b/scene/render_geometry.py
@@ -426,10 +426,10 @@ class SceneCoordAxis(RawSceneObject):
     X_COLOR = glm.vec4(1, 0, 0, 1)
     Y_COLOR = glm.vec4(0, 1, 0, 1)
     Z_COLOR = glm.vec4(0, 0, 1, 1)
-    NEG_COLOR_FACTOR = 150
-    NEG_X_COLOR = glm.vec4(1, NEG_COLOR_FACTOR / 256, NEG_COLOR_FACTOR / 256, 1)
-    NEG_Y_COLOR = glm.vec4(NEG_COLOR_FACTOR / 256, 1, NEG_COLOR_FACTOR / 256, 1)
-    NEG_Z_COLOR = glm.vec4(NEG_COLOR_FACTOR / 256, NEG_COLOR_FACTOR / 256, 1, 1)
+    NEG_COLOR_FACTOR = 150 / 256
+    NEG_X_COLOR = glm.vec4(1, NEG_COLOR_FACTOR, NEG_COLOR_FACTOR, 1)
+    NEG_Y_COLOR = glm.vec4(NEG_COLOR_FACTOR, 1, NEG_COLOR_FACTOR, 1)
+    NEG_Z_COLOR = glm.vec4(NEG_COLOR_FACTOR, NEG_COLOR_FACTOR, 1, 1)
 
     def __init__(self):
         super(SceneCoordAxis, self).__init__()