1 files changed, 19 insertions, 0 deletions
diff --git a/source/blender/gpu/shaders/material/gpu_shader_material_layer_weight.glsl b/source/blender/gpu/shaders/material/gpu_shader_material_layer_weight.glsl
new file mode 100644
index 00000000000..588d295bcc4
--- /dev/null
+++ b/source/blender/gpu/shaders/material/gpu_shader_material_layer_weight.glsl
@@ -0,0 +1,19 @@
+void node_layer_weight(float blend, vec3 N, vec3 I, out float fresnel, out float facing)
+{
+  N = normalize(N);
+
+  /* fresnel */
+  float eta = max(1.0 - blend, 0.00001);
+  vec3 I_view = (ProjectionMatrix[3][3] == 0.0) ? normalize(I) : vec3(0.0, 0.0, -1.0);
+
+  fresnel = fresnel_dielectric(I_view, N, (gl_FrontFacing) ? 1.0 / eta : eta);
+
+  /* facing */
+  facing = abs(dot(I_view, N));
+  if (blend != 0.5) {
+    blend = clamp(blend, 0.0, 0.99999);
+    blend = (blend < 0.5) ? 2.0 * blend : 0.5 / (1.0 - blend);
+    facing = pow(facing, blend);
+  }
+  facing = 1.0 - facing;
+}