Tweak convex hull node and transparent object shader

Now we render at least a vague hint at lighting instead of nothing at
all.

cura/ConvexHullNode.py

@@ -23,7 +23,7 @@ class ConvexHullNode(SceneNode):
         self._original_parent = parent
 
         # Color of the drawn convex hull
-        self._color = Color(35, 35, 35, 192)
+        self._color = Color(0.4, 0.4, 0.4, 1.0)
 
         # The y-coordinate of the convex hull mesh. Must not be 0, to prevent z-fighting.
         self._mesh_height = 0.1

resources/shaders/transparent_object.shader

@@ -1,7 +1,7 @@
 [shaders]
 vertex =
-    uniform highp mat4 u_viewProjectionMatrix;
     uniform highp mat4 u_modelMatrix;
+    uniform highp mat4 u_viewProjectionMatrix;
     uniform highp mat4 u_normalMatrix;
 
     attribute highp vec4 a_vertex;
@@ -10,7 +10,6 @@ vertex =
 
     varying highp vec3 v_vertex;
     varying highp vec3 v_normal;
-    varying highp vec2 v_uvs;
 
     void main()
     {
@@ -19,56 +18,47 @@ vertex =
 
         v_vertex = world_space_vert.xyz;
         v_normal = (u_normalMatrix * normalize(a_normal)).xyz;
-
-        v_uvs = a_uvs;
     }
 
 fragment =
     uniform mediump vec4 u_ambientColor;
     uniform mediump vec4 u_diffuseColor;
     uniform highp vec3 u_lightPosition;
-    uniform highp vec3 u_viewPosition;
+
     uniform mediump float u_opacity;
-    uniform sampler2D u_texture;
 
     varying highp vec3 v_vertex;
     varying highp vec3 v_normal;
-    varying highp vec2 v_uvs;
 
     void main()
     {
-        // Copied from platform.shader, removed texture
-        mediump vec4 final_color = vec4(0.0);
+        mediump vec4 finalColor = vec4(0.0);
 
         /* Ambient Component */
-        final_color += u_ambientColor;
+        finalColor += u_ambientColor;
 
         highp vec3 normal = normalize(v_normal);
-        highp vec3 light_dir = normalize(u_lightPosition - v_vertex);
+        highp vec3 lightDir = normalize(u_lightPosition - v_vertex);
 
         /* Diffuse Component */
-        highp float n_dot_l = clamp(dot(normal, light_dir), 0.0, 1.0);
-        final_color += (n_dot_l * u_diffuseColor);
+        highp float NdotL = clamp(abs(dot(normal, lightDir)), 0.0, 1.0);
+        finalColor += (NdotL * u_diffuseColor);
 
-        final_color.a = u_opacity;
-
-        gl_FragColor = final_color;
+        gl_FragColor = finalColor;
+        gl_FragColor.a = u_opacity;
     }
 
 [defaults]
-u_ambientColor = [0.3, 0.3, 0.3, 1.0]
-u_diffuseColor = [1.0, 1.0, 1.0, 1.0]
+u_ambientColor = [0.1, 0.1, 0.1, 1.0]
+u_diffuseColor = [0.4, 0.4, 0.4, 1.0]
 u_opacity = 0.5
-u_texture = 0
 
 [bindings]
-u_viewProjectionMatrix = view_projection_matrix
 u_modelMatrix = model_matrix
+u_viewProjectionMatrix = view_projection_matrix
 u_normalMatrix = normal_matrix
 u_lightPosition = light_0_position
-u_viewPosition = camera_position
 
 [attributes]
 a_vertex = vertex
 a_normal = normal
-a_uvs = uv0