Cycles: implement pointiness geometry attribute

This attribute means how "pointy" the geometry surface is, which allows to do
effects like dirt maps and wear-off effects on render geometry. This means the
attribute is calculated for the final mesh which means no baking (which implies
UV unwrap) is needed. Apart from this the behavior is quite close to how vertex
dirty colors works.

The new attribute is available as an output socket of Geometry node.

There's no penalty for the render time, only some delay on scene preparation
(the delay is linear of the mesh complexity).

Reviewers: brecht, juicyfruit

Subscribers: eyecandy, venomgfx

Differential Revision: https://developer.blender.org/D1086

1 files changed, 4 insertions, 1 deletions

diff --git a/intern/cycles/kernel/shaders/node_geometry.osl b/intern/cycles/kernel/shaders/node_geometry.osl
index 580ccba8238..2bbaaff2133 100644
--- a/intern/cycles/kernel/shaders/node_geometry.osl
+++ b/intern/cycles/kernel/shaders/node_geometry.osl
@@ -26,7 +26,8 @@ shader node_geometry(
 	output normal TrueNormal = normal(0.0, 0.0, 0.0),
 	output vector Incoming = vector(0.0, 0.0, 0.0),
 	output point Parametric = point(0.0, 0.0, 0.0),
-	output float Backfacing = 0.0)
+	output float Backfacing = 0.0,
+	output float Pointiness = 0.0)
 {
 	Position = P;
 	Normal = NormalIn;
@@ -57,5 +58,7 @@ shader node_geometry(
 		/* otherwise use surface derivatives */
 		Tangent = normalize(dPdu);
 	}
+
+	getattribute("geom:pointiness", Pointiness);
 }