From c1a27a76cf9f40ab9dabb5888ee535e585444fcd Mon Sep 17 00:00:00 2001
From: Mai Lavelle <mai.lavelle@gmail.com>
Date: Wed, 13 Apr 2016 01:17:34 +0200
Subject: Cycles microdisplacement: preserve smooth normals for linear
 subdivison

This way we prevent cracks in the model due to discontinuous normals, by using
smooth normals for displacement instead of always getting flat normals after
linear subdivision.

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D1916
---
 intern/cycles/render/mesh.cpp | 48 +++++++++++++++++++++++++++++++++++--------
 1 file changed, 40 insertions(+), 8 deletions(-)

(limited to 'intern/cycles/render/mesh.cpp')

diff --git a/intern/cycles/render/mesh.cpp b/intern/cycles/render/mesh.cpp
index aa9f773917a..241a1c44ebf 100644
--- a/intern/cycles/render/mesh.cpp
+++ b/intern/cycles/render/mesh.cpp
@@ -1451,31 +1451,63 @@ void Mesh::tessellate(DiagSplit *split)
 {
 	int num_faces = triangles.size();
 
+	add_face_normals();
+	add_vertex_normals();
+
+	Attribute *attr_fN = attributes.find(ATTR_STD_FACE_NORMAL);
+	float3 *fN = attr_fN->data_float3();
+
+	Attribute *attr_vN = attributes.find(ATTR_STD_VERTEX_NORMAL);
+	float3 *vN = attr_vN->data_float3();
+
 	for(int f = 0; f < num_faces; f++) {
 		if(!forms_quad[f]) {
 			/* triangle */
-			LinearTrianglePatch* patch = new LinearTrianglePatch();
-			float3 *hull = patch->hull;
+			LinearTrianglePatch patch;
+			float3 *hull = patch.hull;
+			float3 *normals = patch.normals;
 
 			for(int i = 0; i < 3; i++) {
 				hull[i] = verts[triangles[f].v[i]];
 			}
 
-			split->split_triangle(patch);
-			delete patch;
+			if(smooth[f]) {
+				for(int i = 0; i < 3; i++) {
+					normals[i] = vN[triangles[f].v[i]];
+				}
+			}
+			else {
+				for(int i = 0; i < 3; i++) {
+					normals[i] = fN[f];
+				}
+			}
+
+			split->split_triangle(&patch);
 		}
 		else {
 			/* quad */
-			LinearQuadPatch* patch = new LinearQuadPatch();
-			float3 *hull = patch->hull;
+			LinearQuadPatch patch;
+			float3 *hull = patch.hull;
+			float3 *normals = patch.normals;
 
 			hull[0] = verts[triangles[f  ].v[0]];
 			hull[1] = verts[triangles[f  ].v[1]];
 			hull[3] = verts[triangles[f  ].v[2]];
 			hull[2] = verts[triangles[f+1].v[2]];
 
-			split->split_quad(patch);
-			delete patch;
+			if(smooth[f]) {
+				normals[0] = vN[triangles[f  ].v[0]];
+				normals[1] = vN[triangles[f  ].v[1]];
+				normals[3] = vN[triangles[f  ].v[2]];
+				normals[2] = vN[triangles[f+1].v[2]];
+			}
+			else {
+				for(int i = 0; i < 4; i++) {
+					normals[i] = fN[f];
+				}
+			}
+
+			split->split_quad(&patch);
 
 			// consume second triangle in quad
 			f++;
-- 
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