Fix for material preview not correctly updated

I can see that after updating certain properties as "diffuse_color" the material preview window is refreshed, but when updating non-blender properties like glossy_color, the material preview window is not updated.

Not sure if this is a Blender API problem or a YafaRay problem, but I'm starting to suspect Blender could be the cause. So, I've implemented a forced update of one of the "standard" Blender parameters when one of the YafaRay material parameters is modified. It looks like this is solving the problem and effectively updating the material preview. Let's hope this does not cause other problems (?)

prop/yaf_material.py

@@ -41,10 +41,13 @@ def items_mat2(self, context):
         a.append((mat.name, mat.name, "Second blend material"))
     return(a)
 
+def update_preview(self, context):
+    bpy.data.materials[0].preview_render_type = bpy.data.materials[0].preview_render_type
+
 
 def register():
     Material.mat_type = EnumProperty(
-        name="Material type",
+        update=update_preview, name="Material type",
         items=(
             ('shinydiffusemat', "Shiny Diffuse", "Assign a material type"),
             ('glossy', "Glossy", "Assign a material type"),
@@ -56,118 +59,118 @@ def register():
         default='shinydiffusemat')
 
     Material.diffuse_reflect = FloatProperty(
-        name="Reflection strength",
+        update=update_preview, name="Reflection strength",
         description="Amount of diffuse reflection",
         min=0.0, max=1.0,
         step=1, precision=3,
         soft_min=0.0, soft_max=1.0,
         default=1.000)
 
     Material.specular_reflect = FloatProperty(
-        name="Reflection strength",
+        update=update_preview, name="Reflection strength",
         description="Amount of perfect specular reflection (mirror)",
         min=0.0, max=1.0,
         step=1, precision=3,
         soft_min=0.0, soft_max=1.0,
         default=0.000)
 
     Material.transparency = FloatProperty(
-        name="Transparency",
+        update=update_preview, name="Transparency",
         description="Material transparency",
         min=0.0, max=1.0,
         step=1, precision=3,
         soft_min=0.0, soft_max=1.0,
         default=0.000)
 
     Material.transmit_filter = FloatProperty(
-        name="Transmit filter",
+        update=update_preview, name="Transmit filter",
         description="Amount of tinting of light passing through the Material",
         min=0.0, max=1.0,
         step=1, precision=3,
         soft_min=0.0, soft_max=1.0,
         default=1.000)
 
     Material.fresnel_effect = BoolProperty(
-        name="Fresnel effect",
+        update=update_preview, name="Fresnel effect",
         description="Apply a fresnel effect to specular reflection",
         default=False)
 
     Material.brdf_type = EnumProperty(
-        name="Reflectance model",
+        update=update_preview, name="Reflectance model",
         items=(
             ('oren-nayar', "Oren-Nayar", "Reflectance Model"),
             ('lambert', "Lambert", "Reflectance Model"),
         ),
         default='lambert')
 
     Material.glossy_color = FloatVectorProperty(
-        name="Glossy color",
+        update=update_preview, name="Glossy color",
         description="Glossy Color",
         subtype='COLOR',
         min=0.0, max=1.0,
         default=(1.0, 1.0, 1.0))
 
     # added mirror col property for coated glossy material
     Material.coat_mir_col = FloatVectorProperty(
-        name="Mirror color",
+        update=update_preview, name="Mirror color",
         description="Reflection color of coated layer",
         subtype='COLOR',
         min=0.0, max=1.0,
         default=(1.0, 1.0, 1.0))
 
     # added mirror color property for glass material
     Material.glass_mir_col = FloatVectorProperty(
-        name="Reflection color",
+        update=update_preview, name="Reflection color",
         description="Reflection color of glass material",
         subtype='COLOR',
         min=0.0, max=1.0,
         default=(1.0, 1.0, 1.0))
 
     Material.glossy_reflect = FloatProperty(
-        name="Reflection strength",
+        update=update_preview, name="Reflection strength",
         description="Amount of glossy reflection",
         min=0.0, max=1.0,
         step=1, precision=3,
         soft_min=0.0, soft_max=1.0,
         default=0.000)
 
     Material.exp_u = FloatProperty(
-        name="Exponent U",
+        update=update_preview, name="Exponent U",
         description="Horizontal anisotropic exponent value",
         min=1.0, max=10000.0,
         step=10, precision=2,
         soft_min=1.0, soft_max=10000.0,
         default=50.00)
 
     Material.exp_v = FloatProperty(
-        name="Exponent V",
+        update=update_preview, name="Exponent V",
         description="Vertical anisotropic exponent value",
         min=1.0, max=10000.0,
         step=10, precision=2,
         soft_min=1.0, soft_max=10000.0,
         default=50.00)
 
     Material.exponent = FloatProperty(
-        name="Exponent",
+        update=update_preview, name="Exponent",
         description="Blur of the glossy reflection, higher exponent = sharper reflections",
         min=1.0, max=10000.0,
         step=10, precision=2,
         soft_min=1.0, soft_max=10000.0,
         default=500.00)
 
     Material.as_diffuse = BoolProperty(
-        name="Use photon map",
+        update=update_preview, name="Use photon map",
         description="Treat glossy component as diffuse",
         default=False)
 
     Material.anisotropic = BoolProperty(
-        name="Anisotropic",
+        update=update_preview, name="Anisotropic",
         description="Use anisotropic reflections",
         default=False)
 
     # added IOR property for refraction
     Material.IOR_refraction = FloatProperty(
-        name="IOR",
+        update=update_preview, name="IOR",
         description="Index of refraction",
         min=0.0, max=30.0,
         step=1, precision=3,
@@ -176,22 +179,22 @@ def register():
 
     # added IOR property for reflection
     Material.IOR_reflection = FloatProperty(
-        name="IOR",
+        update=update_preview, name="IOR",
         description="Fresnel reflection strength",
         min=1.0, max=30.0,
         step=1, precision=3,
         soft_min=1.0, soft_max=30.0,
         default=1.800)
 
     Material.absorption = FloatVectorProperty(
-        name="Color and absorption",
+        update=update_preview, name="Color and absorption",
         description="Glass volumetric absorption color. White disables absorption",
         subtype='COLOR',
         min=0.0, max=1.0,
         default=(1.0, 1.0, 1.0))
 
     Material.absorption_dist = FloatProperty(
-        name="Abs. distance",
+        update=update_preview, name="Abs. distance",
         description="Absorption distance scale",
         min=0.0, max=100.0,
         step=1, precision=4,
@@ -200,22 +203,22 @@ def register():
 
     # added transmit filter for glass material
     Material.glass_transmit = FloatProperty(
-        name="Transmit filter",
+        update=update_preview, name="Transmit filter",
         description="Filter strength applied to refracted light",
         min=0.0, max=1.0,
         step=1, precision=3,
         soft_min=0.0, soft_max=1.0,
         default=1.000)
 
     Material.filter_color = FloatVectorProperty(
-        name="Filter color",
+        update=update_preview, name="Filter color",
         description="Filter color for refracted light of glass, also tint transparent shadows if enabled",
         subtype='COLOR',
         min=0.0, max=1.0,
         default=(1.0, 1.0, 1.0))
 
     Material.dispersion_power = FloatProperty(
-        name="Disp. power",
+        update=update_preview, name="Disp. power",
         description="Strength of dispersion effect, disabled when 0",
         min=0.0, max=5.0,
         step=1, precision=4,
@@ -224,51 +227,51 @@ def register():
 
     # added refraction roughness propertie for roughglass material
     Material.refr_roughness = FloatProperty(
-        name="Exponent",
+        update=update_preview, name="Exponent",
         description="Roughness factor for glass material",
         min=0.0, max=1.0,
         step=1, precision=3,
         soft_min=0.0, soft_max=1.0,
         default=0.200)
 
     Material.fake_shadows = BoolProperty(
-        name="Fake shadows",
+        update=update_preview, name="Fake shadows",
         description="Let light straight through for shadow calculation. Not to be used with dispersion",
         default=False)
 
     Material.blend_value = FloatProperty(
-        name="Blend value",
+        update=update_preview, name="Blend value",
         description="The mixing balance: 0 -> only material 1, 1.0 -> only material 2",
         min=0.0, max=1.0,
         step=3, precision=3,
         soft_min=0.0, soft_max=1.0,
         default=0.500)
 
     Material.sigma = FloatProperty(
-        name="Sigma",
+        update=update_preview, name="Sigma",
         description="Roughness of the surface",
         min=0.0, max=1.0,
         step=1, precision=5,
         soft_min=0.0, soft_max=1.0,
         default=0.10000)
 
     Material.rough = BoolProperty(
-        name="rough",
+        update=update_preview, name="rough",
         description="",
         default=False)
 
     Material.coated = BoolProperty(
-        name="coated",
+        update=update_preview, name="coated",
         description="",
         default=False)
 
     Material.material1 = EnumProperty(
-        name="Material one",
+        update=update_preview, name="Material one",
         description="First blend material",
         items=items_mat1)
 
     Material.material2 = EnumProperty(
-        name="Material two",
+        update=update_preview, name="Material two",
         description="Second blend material",
         items=items_mat2)