1 files changed, 52 insertions, 0 deletions
diff --git a/source/blender/draw/intern/shaders/common_subdiv_vbo_lnor_comp.glsl b/source/blender/draw/intern/shaders/common_subdiv_vbo_lnor_comp.glsl
new file mode 100644
index 00000000000..41a8df3cf82
--- /dev/null
+++ b/source/blender/draw/intern/shaders/common_subdiv_vbo_lnor_comp.glsl
@@ -0,0 +1,52 @@
+
+/* To be compile with common_subdiv_lib.glsl */
+
+layout(std430, binding = 1) readonly buffer inputVertexData
+{
+  PosNorLoop pos_nor[];
+};
+
+layout(std430, binding = 2) readonly buffer extraCoarseFaceData
+{
+  uint extra_coarse_face_data[];
+};
+
+layout(std430, binding = 3) writeonly buffer outputLoopNormals
+{
+  vec3 output_lnor[];
+};
+
+void main()
+{
+  /* We execute for each quad. */
+  uint quad_index = get_global_invocation_index();
+  if (quad_index >= total_dispatch_size) {
+    return;
+  }
+
+  /* The start index of the loop is quad_index * 4. */
+  uint start_loop_index = quad_index * 4;
+
+  uint coarse_quad_index = coarse_polygon_index_from_subdiv_quad_index(quad_index,
+                                                                       coarse_poly_count);
+
+  if ((extra_coarse_face_data[coarse_quad_index] & coarse_face_smooth_mask) != 0) {
+    /* Face is smooth, use vertex normals. */
+    for (int i = 0; i < 4; i++) {
+      PosNorLoop pos_nor_loop = pos_nor[start_loop_index + i];
+      output_lnor[start_loop_index + i] = get_vertex_nor(pos_nor_loop);
+    }
+  }
+  else {
+    /* Face is flat shaded, compute flat face normal from an inscribed triangle. */
+    vec3 verts[3];
+    for (int i = 0; i < 3; i++) {
+      verts[i] = get_vertex_pos(pos_nor[start_loop_index + i]);
+    }
+
+    vec3 face_normal = normalize(cross(verts[1] - verts[0], verts[2] - verts[0]));
+    for (int i = 0; i < 4; i++) {
+      output_lnor[start_loop_index + i] = face_normal;
+    }
+  }
+}