Cycles: add bevel shader, for raytrace based rounded edges.

The algorithm averages normals from nearby surfaces. It uses the same
sampling strategy as BSSRDFs, casting rays along the normal and two
orthogonal axes, and combining the samples with MIS.

The main concern here is that we are introducing raytracing inside
shader evaluation, which could be quite bad for GPU performance and
stack memory usage. In practice it doesn't seem so bad though.

Note that using this feature can easily slow down renders 20%, and
that if you care about performance then it's better to use a bevel
modifier. Mainly this is useful for baking, and for cases where the
mesh topology makes it difficult for the bevel modifier to work well.

Differential Revision: https://developer.blender.org/D2803

4 files changed, 73 insertions, 0 deletions

diff --git a/source/blender/nodes/CMakeLists.txt b/source/blender/nodes/CMakeLists.txt
index c5a3c70100b..21f9afec903 100644
--- a/source/blender/nodes/CMakeLists.txt
+++ b/source/blender/nodes/CMakeLists.txt
@@ -192,6 +192,7 @@ set(SRC
 	shader/nodes/node_shader_script.c
 	shader/nodes/node_shader_subsurface_scattering.c
 	shader/nodes/node_shader_tangent.c
+	shader/nodes/node_shader_bevel.c
 	shader/nodes/node_shader_tex_brick.c
 	shader/nodes/node_shader_tex_checker.c
 	shader/nodes/node_shader_tex_coord.c
diff --git a/source/blender/nodes/NOD_shader.h b/source/blender/nodes/NOD_shader.h
index 804c1897a27..f7d36e3dbef 100644
--- a/source/blender/nodes/NOD_shader.h
+++ b/source/blender/nodes/NOD_shader.h
@@ -78,6 +78,7 @@ void register_node_type_sh_tex_brick(void);
 void register_node_type_sh_tex_pointdensity(void);
 
 void register_node_type_sh_attribute(void);
+void register_node_type_sh_bevel(void);
 void register_node_type_sh_geometry(void);
 void register_node_type_sh_light_path(void);
 void register_node_type_sh_light_falloff(void);
diff --git a/source/blender/nodes/NOD_static_types.h b/source/blender/nodes/NOD_static_types.h
index 02422a8622a..13844298c5a 100644
--- a/source/blender/nodes/NOD_static_types.h
+++ b/source/blender/nodes/NOD_static_types.h
@@ -126,6 +126,7 @@ DefNode( ShaderNode,     SH_NODE_UVMAP,              def_sh_uvmap,           "UV
 DefNode( ShaderNode,     SH_NODE_UVALONGSTROKE,      def_sh_uvalongstroke,   "UVALONGSTROKE",      UVAlongStroke,    "UV Along Stroke",   ""       )
 DefNode( ShaderNode,     SH_NODE_SEPXYZ,             0,                      "SEPXYZ",             SeparateXYZ,      "Separate XYZ",      ""       )
 DefNode( ShaderNode,     SH_NODE_COMBXYZ,            0,                      "COMBXYZ",            CombineXYZ,       "Combine XYZ",       ""       )
+DefNode( ShaderNode,     SH_NODE_BEVEL,              def_sh_bevel,           "BEVEL",              Bevel,            "Bevel",             ""       )
 
 DefNode( CompositorNode, CMP_NODE_VIEWER,         def_cmp_viewer,         "VIEWER",         Viewer,           "Viewer",            ""              )
 DefNode( CompositorNode, CMP_NODE_RGB,            0,                      "RGB",            RGB,              "RGB",               ""              )
diff --git a/source/blender/nodes/shader/nodes/node_shader_bevel.c b/source/blender/nodes/shader/nodes/node_shader_bevel.c
new file mode 100644
index 00000000000..fc7d109f123
--- /dev/null
+++ b/source/blender/nodes/shader/nodes/node_shader_bevel.c
@@ -0,0 +1,70 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2005 Blender Foundation.
+ * All rights reserved.
+ *
+ * The Original Code is: all of this file.
+ *
+ * Contributor(s): none yet.
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+#include "../node_shader_util.h"
+
+/* **************** OUTPUT ******************** */
+
+static bNodeSocketTemplate sh_node_bevel_in[] = {
+	{	SOCK_FLOAT, 0, N_("Radius"), 0.05f, 0.0f, 0.0f, 0.0f, 0.0f, 1000.0f},
+	{	SOCK_VECTOR, 1, N_("Normal"), 0.0f, 0.0f, 0.0f, 1.0f, -1.0f, 1.0f, PROP_NONE, SOCK_HIDE_VALUE},
+	{	-1, 0, ""	}
+};
+
+static bNodeSocketTemplate sh_node_bevel_out[] = {
+	{	SOCK_VECTOR, 0, N_("Normal"), 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f},
+	{	-1, 0, ""	}
+};
+
+static void node_shader_init_bevel(bNodeTree *UNUSED(ntree), bNode *node)
+{
+	node->custom1 = 4; /* samples */
+}
+
+static int gpu_shader_bevel(GPUMaterial *mat, bNode *UNUSED(node), bNodeExecData *UNUSED(execdata), GPUNodeStack *in, GPUNodeStack *out)
+{
+	if (!in[1].link) {
+		in[1].link = GPU_builtin(GPU_VIEW_NORMAL);
+	}
+
+	return GPU_stack_link(mat, "node_bevel", in, out);
+}
+
+/* node type definition */
+void register_node_type_sh_bevel(void)
+{
+	static bNodeType ntype;
+
+	sh_node_type_base(&ntype, SH_NODE_BEVEL, "Bevel", NODE_CLASS_INPUT, 0);
+	node_type_compatibility(&ntype, NODE_NEW_SHADING);
+	node_type_socket_templates(&ntype, sh_node_bevel_in, sh_node_bevel_out);
+	node_type_init(&ntype, node_shader_init_bevel);
+	node_type_storage(&ntype, "", NULL, NULL);
+	node_type_gpu(&ntype, gpu_shader_bevel);
+
+	nodeRegisterType(&ntype);
+}