diff --git a/src/graphics/material.nim b/src/graphics/material.nim
index 44e7f7b..c6359a9 100644
--- a/src/graphics/material.nim
+++ b/src/graphics/material.nim
@@ -40,7 +40,7 @@ when defined(nimdoc):
 
 # Forward declarations
 func add_line_numbers(s: string, first: int=1):string
-proc newMaterial*(engine: MyouEngine, name: string, scene: Scene,
+proc newMaterial*(engine: MyouEngine, name: string, scene: Scene = nil,
         vertex = "",
         fragment = "",
         textures = initOrderedTable[string, Texture](),
@@ -122,7 +122,7 @@ func add_line_numbers(s: string, first: int=1):string =
         lines[i] = $(i+first) & " " & line
     return lines.join("\n")
 
-proc newMaterial*(engine: MyouEngine, name: string, scene: Scene,
+proc newMaterial*(engine: MyouEngine, name: string, scene: Scene = nil,
         vertex = "",
         fragment = "",
         textures = initOrderedTable[string, Texture](),
@@ -166,7 +166,7 @@ proc newSolidMaterial*(engine: MyouEngine, name: string, color: Vec4): Material
             }}""",
     )
 
-proc newVertexColordMaterial*(engine: MyouEngine, name: string): Material =
+proc newVertexColorMaterial*(engine: MyouEngine, name = "vertex color"): Material =
     newMaterial(engine, name, nil,
         fragment = dedent """
             in vec4 vcol;
@@ -190,7 +190,7 @@ proc get_shader*(self: Material, mesh: Mesh): Shader =
         shader = new Shader
         self.shaders[mesh.layout] = shader
         self.last_shader = shader
-        shader.initShader(self.engine, self, mesh.data.layout & mesh.data.tf_layout, 
+        shader.initShader(self.engine, self, mesh.data.layout & mesh.data.tf_layout,
             mesh.vertex_modifiers, mesh.material_defines)
     return shader
 
@@ -404,7 +404,7 @@ proc initShader*(self: Shader, engine: MyouEngine, material: Material,
                 @[]) & varyings_assign & modifiers_post_bodies &
             "gl_Position = proj_co;\n}"
         ).join("\n  ")
-        vs = (version_line & extension_lines & vs_head & varyings_uniform_decl & 
+        vs = (version_line & extension_lines & vs_head & varyings_uniform_decl &
             attribute_lines & vertex_shader_library & modifiers_uniforms & varyings_decl & vs_body).join("\n")
     when defined(myouStoreGLSL):
         self.vs_code = vs
@@ -502,6 +502,8 @@ proc initShader*(self: Shader, engine: MyouEngine, material: Material,
 
     # TODO: use KHR_parallel_shader_compile
 
+    # TODO: identify unused uniforms (at least unused textures)
+
     var ubo_names = newSeqOfCap[string](material.ubos.len)
     self.ubos.setLen 0
     for ubo in material.ubos & modifier_ubos:
@@ -515,31 +517,31 @@ proc initShader*(self: Shader, engine: MyouEngine, material: Material,
         assert ubo.name notin ubo_names, "There's more than one UBO with name " & ubo.name & " in {material.name}"
         ubo_names.add ubo.name
     ubo_names.setLen 0
-    
+
     self.texture_locations.setLen 0
     var extra_location_count = 0
     for name in material.textures.keys:
         self.texture_locations.add glGetUniformLocation(prog, name.cstring)
         if defined(myouEnsureTextureLocations) and not defined(release):
             assert self.texture_locations[^1] != -1, "invalid texture location for " & name
-    
+
     self.cubemap_locations.setLen 0
     self.shadowmap_location = -1
     if material.scene != nil:
         self.shadowmap_location = glGetUniformLocation(prog, "shadow_maps".cstring)
         if self.shadowmap_location != -1:
             extra_location_count.inc
-    
+
         for i in 0 ..< material.scene.max_cubemaps:
             # TODO: test with a single glUniform1iv instead of changing
             #       the individual array elements
-            self.cubemap_locations.add glGetUniformLocation(prog, 
+            self.cubemap_locations.add glGetUniformLocation(prog,
                 (&"cube_maps[{i}]").cstring)
             # when not defined(release):
             #     assert self.shadowmap_locations[^1] != -1
         # dump material.name
         # dump self.cubemap_locations
-    
+
     assert self.texture_locations.len + self.cubemap_locations.len +
             extra_location_count <= self.engine.renderer.max_textures
 
@@ -551,5 +553,3 @@ proc use*(self: Shader): GLuint {.inline,discardable.} =
 
 proc destroy*(self: Shader) =
     self.program = 0.GPUProgram
-
-