Fix T100377: EEVEE: Regression 3.2 normalmap node broken

This was caused by un-wanted normalization. This is a requirement of
the MikkTspace. The issue is that g_data.N is expected to be normalized
by many other functions and overriden by bump displacement.

Adding a new global variable containing the interpolated normal fixes the
issue AND make it match cycles behavior better (mix between bump and
interpolated normal).

4 files changed, 11 insertions, 7 deletions

diff --git a/source/blender/draw/engines/eevee/shaders/surface_lib.glsl b/source/blender/draw/engines/eevee/shaders/surface_lib.glsl
index 488e229bff7..b984a6df7b3 100644
--- a/source/blender/draw/engines/eevee/shaders/surface_lib.glsl
+++ b/source/blender/draw/engines/eevee/shaders/surface_lib.glsl
@@ -98,10 +98,11 @@ GlobalData init_globals(void)
 
 #  if defined(WORLD_BACKGROUND) || defined(PROBE_CAPTURE)
   surf.P = transform_direction(ViewMatrixInverse, -viewCameraVec(viewPosition));
-  surf.N = surf.Ng = -surf.P;
+  surf.N = surf.Ng = surf.Ni = -surf.P;
   surf.ray_length = 0.0;
 #  else
   surf.P = worldPosition;
+  surf.Ni = worldNormal;
   surf.N = safe_normalize(worldNormal);
   surf.Ng = safe_normalize(cross(dFdx(surf.P), dFdy(surf.P)));
   surf.ray_length = distance(surf.P, cameraPos);
@@ -123,7 +124,7 @@ GlobalData init_globals(void)
     cos_theta = hairThickTime / hairThickness;
   }
   float sin_theta = sqrt(max(0.0, 1.0 - cos_theta * cos_theta));
-  surf.N = safe_normalize(worldNormal * sin_theta + B * cos_theta);
+  surf.N = surf.Ni = safe_normalize(worldNormal * sin_theta + B * cos_theta);
   surf.curve_T = -hairTangent;
   /* Costly, but follows cycles per pixel tangent space (not following curve shape). */
   surf.curve_B = cross(V, surf.curve_T);
diff --git a/source/blender/draw/engines/eevee_next/shaders/eevee_surf_lib.glsl b/source/blender/draw/engines/eevee_next/shaders/eevee_surf_lib.glsl
index 30b48edaa78..18e748596d5 100644
--- a/source/blender/draw/engines/eevee_next/shaders/eevee_surf_lib.glsl
+++ b/source/blender/draw/engines/eevee_next/shaders/eevee_surf_lib.glsl
@@ -40,7 +40,7 @@ void init_globals_curves()
   /* Shade as a cylinder. */
   float cos_theta = interp.curves_time_width / interp.curves_thickness;
   float sin_theta = sqrt(max(0.0, 1.0 - cos_theta * cos_theta));
-  g_data.N = normalize(interp.N * sin_theta + interp.curves_binormal * cos_theta);
+  g_data.N = g_data.Ni = normalize(interp.N * sin_theta + interp.curves_binormal * cos_theta);
 
   /* Costly, but follows cycles per pixel tangent space (not following curve shape). */
   vec3 V = cameraVec(g_data.P);
@@ -67,6 +67,7 @@ void init_globals()
 {
   /* Default values. */
   g_data.P = interp.P;
+  g_data.Ni = interp.N;
   g_data.N = safe_normalize(interp.N);
   g_data.Ng = g_data.N;
   g_data.is_strand = false;
diff --git a/source/blender/gpu/shaders/gpu_shader_codegen_lib.glsl b/source/blender/gpu/shaders/gpu_shader_codegen_lib.glsl
index 6091a5c834a..c0821085c8d 100644
--- a/source/blender/gpu/shaders/gpu_shader_codegen_lib.glsl
+++ b/source/blender/gpu/shaders/gpu_shader_codegen_lib.glsl
@@ -187,8 +187,10 @@ struct ClosureTransparency {
 struct GlobalData {
   /** World position. */
   vec3 P;
-  /** Surface Normal. */
+  /** Surface Normal. Normalized, overriden by bump displacement. */
   vec3 N;
+  /** Raw interpolated normal (non-normalized) data. */
+  vec3 Ni;
   /** Geometric Normal. */
   vec3 Ng;
   /** Curve Tangent Space. */
diff --git a/source/blender/gpu/shaders/material/gpu_shader_material_normal_map.glsl b/source/blender/gpu/shaders/material/gpu_shader_material_normal_map.glsl
index a54dc59ddfe..3fc4992f7c4 100644
--- a/source/blender/gpu/shaders/material/gpu_shader_material_normal_map.glsl
+++ b/source/blender/gpu/shaders/material/gpu_shader_material_normal_map.glsl
@@ -3,13 +3,13 @@
 void node_normal_map(vec4 tangent, vec3 texnormal, out vec3 outnormal)
 {
   if (all(equal(tangent, vec4(0.0, 0.0, 0.0, 1.0)))) {
-    outnormal = g_data.N;
+    outnormal = g_data.Ni;
     return;
   }
   tangent *= (FrontFacing ? 1.0 : -1.0);
-  vec3 B = tangent.w * cross(g_data.N, tangent.xyz) * sign(ObjectInfo.w);
+  vec3 B = tangent.w * cross(g_data.Ni, tangent.xyz) * sign(ObjectInfo.w);
 
-  outnormal = texnormal.x * tangent.xyz + texnormal.y * B + texnormal.z * g_data.N;
+  outnormal = texnormal.x * tangent.xyz + texnormal.y * B + texnormal.z * g_data.Ni;
   outnormal = normalize(outnormal);
 }
 #endif