Cycles: change volume step size controls, auto adjust based on voxel size

By default it will now set the step size to the voxel size for smoke and
volume objects, and 1/10th the bounding box for procedural volume shaders.

New settings are:
* Scene render/preview step rate: to globally adjust detail and performance
* Material step rate: multiplied with auto detected per-object step size
* World step size: distance to steo for world shader

Differential Revision: https://developer.blender.org/D1777

1 files changed, 29 insertions, 7 deletions

diff --git a/intern/cycles/blender/addon/properties.py b/intern/cycles/blender/addon/properties.py
index cd72da128aa..c91e210bbd8 100644
--- a/intern/cycles/blender/addon/properties.py
+++ b/intern/cycles/blender/addon/properties.py
@@ -444,13 +444,20 @@ class CyclesRenderSettings(bpy.types.PropertyGroup):
         default=8,
     )
 
-    volume_step_size: FloatProperty(
-        name="Step Size",
-        description="Distance between volume shader samples when rendering the volume "
-        "(lower values give more accurate and detailed results, but also increased render time)",
-        default=0.1,
-        min=0.0000001, max=100000.0, soft_min=0.01, soft_max=1.0, precision=4,
-        unit='LENGTH'
+    volume_step_rate: FloatProperty(
+        name="Step Rate",
+        description="Globally adjust detail for volume rendering, on top of automatically estimated step size. "
+                    "Higher values reduce render time, lower values render with more detail",
+        default=1.0,
+        min=0.01, max=100.0, soft_min=0.1, soft_max=10.0, precision=2
+    )
+
+    volume_preview_step_rate: FloatProperty(
+        name="Step Rate",
+        description="Globally adjust detail for volume rendering, on top of automatically estimated step size. "
+                    "Higher values reduce render time, lower values render with more detail",
+        default=1.0,
+        min=0.01, max=100.0, soft_min=0.1, soft_max=10.0, precision=2
     )
 
     volume_max_steps: IntProperty(
@@ -934,6 +941,14 @@ class CyclesMaterialSettings(bpy.types.PropertyGroup):
         default='LINEAR',
     )
 
+    volume_step_rate: FloatProperty(
+        name="Step Rate",
+        description="Scale the distance between volume shader samples when rendering the volume "
+                    "(lower values give more accurate and detailed results, but also increased render time)",
+        default=1.0,
+        min=0.001, max=1000.0, soft_min=0.1, soft_max=10.0, precision=4
+    )
+
     displacement_method: EnumProperty(
         name="Displacement Method",
         description="Method to use for the displacement",
@@ -1044,6 +1059,13 @@ class CyclesWorldSettings(bpy.types.PropertyGroup):
         items=enum_volume_interpolation,
         default='LINEAR',
     )
+    volume_step_size: FloatProperty(
+        name="Step Size",
+        description="Distance between volume shader samples when rendering the volume "
+                    "(lower values give more accurate and detailed results, but also increased render time)",
+        default=1.0,
+        min=0.0000001, max=100000.0, soft_min=0.1, soft_max=100.0, precision=4
+    )
 
     @classmethod
     def register(cls):