Fix T63435 Incorrect fresnel and normals for hair strands on EEVEE

2 files changed, 7 insertions, 1 deletions

diff --git a/source/blender/gpu/intern/gpu_codegen.c b/source/blender/gpu/intern/gpu_codegen.c
index aef68333b6f..a77bba5ab86 100644
--- a/source/blender/gpu/intern/gpu_codegen.c
+++ b/source/blender/gpu/intern/gpu_codegen.c
@@ -892,7 +892,13 @@ static char *code_generate_fragment(GPUMaterial *material,
     BLI_dynstr_append(ds, "\t#define invlocaltoviewmat ModelViewMatrixInverse\n");
   }
   if (builtins & GPU_VIEW_NORMAL) {
+    BLI_dynstr_append(ds, "#ifdef HAIR_SHADER\n");
+    BLI_dynstr_append(ds, "\tvec3 n;\n");
+    BLI_dynstr_append(ds, "\tworld_normals_get(n);\n");
+    BLI_dynstr_append(ds, "\tvec3 facingnormal = transform_direction(ViewMatrix, n);\n");
+    BLI_dynstr_append(ds, "#else\n");
     BLI_dynstr_append(ds, "\tvec3 facingnormal = gl_FrontFacing? viewNormal: -viewNormal;\n");
+    BLI_dynstr_append(ds, "#endif\n");
   }
   if (builtins & GPU_VIEW_POSITION) {
     BLI_dynstr_append(ds, "\t#define viewposition viewPosition\n");
diff --git a/source/blender/gpu/shaders/gpu_shader_material.glsl b/source/blender/gpu/shaders/gpu_shader_material.glsl
index c64623eeaf7..cf7a83e8a87 100644
--- a/source/blender/gpu/shaders/gpu_shader_material.glsl
+++ b/source/blender/gpu/shaders/gpu_shader_material.glsl
@@ -3407,7 +3407,7 @@ void world_normals_get(out vec3 N)
     /* Shade as a cylinder. */
     cos_theta = hairThickTime / hairThickness;
   }
-  float sin_theta = sqrt(max(0.0, 1.0f - cos_theta * cos_theta));
+  float sin_theta = sqrt(max(0.0, 1.0 - cos_theta * cos_theta));
   N = normalize(worldNormal * sin_theta + B * cos_theta);
 #  else
   N = gl_FrontFacing ? worldNormal : -worldNormal;