From ffd3c6a6e82b437f62eb9ebd3cd861c048d13448 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Sun, 13 Dec 2020 23:45:14 +0300
Subject: [PATCH] Fix bump mapping

---
 libs/gfx/source/renderer/deferred.cpp | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/libs/gfx/source/renderer/deferred.cpp b/libs/gfx/source/renderer/deferred.cpp
index de35b5d6..bc9920f5 100644
--- a/libs/gfx/source/renderer/deferred.cpp
+++ b/libs/gfx/source/renderer/deferred.cpp
@@ -69,34 +69,27 @@ out vec4 color;
 out vec2 texcoord;
 out vec3 normal;
 
-out mat3 normal_transform;
-
 void main()
 {
 	vec4 pos = in_position;
 	vec3 n = in_normal;
 
-	mat3 nt = mat3(1.0);
-
 	if ((u_flag_mask & O_PRE_TRANSFORM) != 0u)
 	{
 		pos = vec4(u_pre_transform * pos, 1.0);
 		n = u_pre_transform * vec4(n, 0.0);
-		nt = mat3(u_pre_transform);
 	}
 
 	if ((u_flag_mask & O_INSTANCED) != 0u)
 	{
 		pos = vec4(transpose(in_instance_transform) * pos, 1.0);
 		n = transpose(in_instance_transform) * vec4(n, 0.0);
-		nt = mat3(transpose(in_instance_transform)) * nt;
 	}
 
 	if ((u_flag_mask & O_POST_TRANSFORM) != 0u)
 	{
 		pos = vec4(u_post_transform * pos, 1.0);
 		n = u_post_transform * vec4(n, 0.0);
-		nt = mat3(u_post_transform) * nt;
 	}
 
 	position = pos.xyz;
@@ -106,7 +99,6 @@ void main()
 	color = in_color;
 	texcoord = in_texcoord;
 	normal = n;
-	normal_transform = nt;
 }
 )";
 
@@ -123,7 +115,6 @@ in vec3 position;
 in vec4 color;
 in vec2 texcoord;
 in vec3 normal;
-in mat3 normal_transform;
 
 layout (location = 0) out vec3 out0;
 layout (location = 1) out vec4 out1;
@@ -201,7 +192,23 @@ void main()
 	vec3 n = normal;
 	if ((u_flag_mask & O_BUMP_MAP) != 0u)
 	{
-		n = normal_transform * (2.0 * texture(u_bump_texture, texcoord).xyz - vec3(1.0));
+		mat2 dtdf;
+		dtdf[0] = dFdx(texcoord);
+		dtdf[1] = dFdy(texcoord);
+
+		mat2x3 dpdf;
+		dpdf[0] = dFdx(position);
+		dpdf[1] = dFdy(position);
+
+		mat2x3 dpdt = dpdf * inverse(dtdf);
+
+		vec3 z = n;
+		vec3 x = normalize(dpdt[0]);
+		vec3 y = normalize(dpdt[1]);
+
+		vec3 v = texture(u_bump_texture, texcoord).xyz * 2.0 - vec3(1.0);
+
+		n = normalize(v.x * x + v.y * y + v.z * z);
 	}
 
 	out0 = position;