Eevee: Fix black mesh when tangent is not present

In this case, the generic vertex attribute is {0,0,0,1}. So we look for
this case.

This fixes black text objects with a normal map applied. Also this could
help porting sculpt mode drawing to Eevee without supporting normal
mapping.

Note that will just fix black meshes due to T61870 but objects will not
show their normal map. So it's not a fix for this issue.

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 f3386ec3a65..513dfad9d8a 100644
--- a/source/blender/gpu/intern/gpu_codegen.c
+++ b/source/blender/gpu/intern/gpu_codegen.c
@@ -1001,7 +1001,7 @@ static char *code_generate_vertex(ListBase *nodes, const char *vert_code, bool u
 			if (input->source == GPU_SOURCE_ATTR && input->attr_first) {
 				if (input->attr_type == CD_TANGENT) { /* silly exception */
 					BLI_dynstr_appendf(
-					        ds, "\tvar%d%s.xyz = normalize(NormalMatrix * att%d.xyz);\n",
+					        ds, "\tvar%d%s.xyz = NormalMatrix * att%d.xyz;\n",
 					        input->attr_id, use_geom ? "g" : "", input->attr_id);
 					BLI_dynstr_appendf(
 					        ds, "\tvar%d%s.w = att%d.w;\n",
diff --git a/source/blender/gpu/shaders/gpu_shader_material.glsl b/source/blender/gpu/shaders/gpu_shader_material.glsl
index d91b6b77b86..5625cbb69c7 100644
--- a/source/blender/gpu/shaders/gpu_shader_material.glsl
+++ b/source/blender/gpu/shaders/gpu_shader_material.glsl
@@ -2967,6 +2967,12 @@ void node_object_info(mat4 obmat, vec3 info, out vec3 location, out float object
 
 void node_normal_map(vec4 tangent, vec3 normal, vec3 texnormal, out vec3 outnormal)
 {
+	if (all(equal(tangent, vec4(0.0, 0.0, 0.0, 1.0)))) {
+		outnormal = normal;
+		return;
+	}
+
+	tangent.xyz = normalize(tangent.xyz);
 	vec3 B = tangent.w * cross(normal, tangent.xyz);
 
 	outnormal = texnormal.x * tangent.xyz + texnormal.y * B + texnormal.z * normal;