From 2a3f48fd508a14cc0135044c1d0ad974a142692b Mon Sep 17 00:00:00 2001
From: Ivan Avdeev <me@w23.ru>
Date: Thu, 2 Nov 2023 13:47:31 -0400
Subject: [PATCH] vk: fix occasional inverted normal maps

When texture coordinates are inverted, it makes tangent look into
oppsite direction, which inverts TBN and therefore normal map.

Make sure the tangent points to a consistent direction.

Fixes #627
---
 ref/vk/TODO.md         |  3 ++-
 ref/vk/vk_brush.c      | 28 ++++++++++++++++++++--------
 ref/vk/vk_descriptor.c |  2 +-
 3 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/ref/vk/TODO.md b/ref/vk/TODO.md
index a864bfd6..cd82891c 100644
--- a/ref/vk/TODO.md
+++ b/ref/vk/TODO.md
@@ -1,7 +1,8 @@
 # 2023-11-02 E323
 - [x] lol meta: read and sort issues
 - [x] merge from upstream
-- [ ] hevsuit glitches
+- [x] hevsuit glitches
+- [x] inverted normal map orientation
 - [ ] massage shaders: consolidate all bindings explicitly
 - [ ] skip sorting-by-texture when loading brush models (=> geometry count explosion; i.e. kusochki count will explode too)
 - [ ] kusochki-vs-materials
diff --git a/ref/vk/vk_brush.c b/ref/vk/vk_brush.c
index 1c5fc49e..19eadc46 100644
--- a/ref/vk/vk_brush.c
+++ b/ref/vk/vk_brush.c
@@ -1183,9 +1183,6 @@ static qboolean fillBrushSurfaces(fill_geometries_args_t args) {
 				// FIXME make an explicit list of dynamic-uv geometries
 			}
 
-			VectorCopy(surf->texinfo->vecs[0], tangent);
-			VectorNormalize(tangent);
-
 			vec3_t surf_normal;
 			getSurfaceNormal(surf, surf_normal);
 
@@ -1217,7 +1214,6 @@ static qboolean fillBrushSurfaces(fill_geometries_args_t args) {
 					}
 
 					float s_off = 0, t_off = 0;
-					float s_sc = 1, t_sc = 1;
 
 					if (psurf && (psurf->flags & Patch_Surface_TexOffset)) {
 						s_off = psurf->tex_offset[0];
@@ -1225,15 +1221,31 @@ static qboolean fillBrushSurfaces(fill_geometries_args_t args) {
 					}
 
 					if (psurf && (psurf->flags & Patch_Surface_TexScale)) {
-						s_sc = psurf->tex_scale[0];
-						t_sc = psurf->tex_scale[1];
+						svec[0] *= psurf->tex_scale[0];
+						svec[1] *= psurf->tex_scale[0];
+						svec[2] *= psurf->tex_scale[0];
+						tvec[0] *= psurf->tex_scale[1];
+						tvec[1] *= psurf->tex_scale[1];
+						tvec[2] *= psurf->tex_scale[1];
 					}
 
-					const float s = s_off + s_sc * DotProduct( in_vertex->position, svec ) + svec[3];
-					const float t = t_off + t_sc * DotProduct( in_vertex->position, tvec ) + tvec[3];
+					const float s = s_off + DotProduct( in_vertex->position, svec ) + svec[3];
+					const float t = t_off + DotProduct( in_vertex->position, tvec ) + tvec[3];
 
 					vertex.gl_tc[0] = s / surf->texinfo->texture->width;
 					vertex.gl_tc[1] = t / surf->texinfo->texture->height;
+
+					VectorCopy(svec, tangent);
+					VectorNormalize(tangent);
+
+					// "Inverted" texture mapping should not lead to inverted tangent/normal map
+					// Make sure that orientation is preserved.
+					{
+						vec4_t stnorm;
+						CrossProduct(tvec, svec, stnorm);
+						if (DotProduct(stnorm, surf_normal) < 0.)
+							VectorNegate(tangent, tangent);
+					}
 				}
 
 				// lightmap texture coordinates
diff --git a/ref/vk/vk_descriptor.c b/ref/vk/vk_descriptor.c
index 4618916b..05ede5aa 100644
--- a/ref/vk/vk_descriptor.c
+++ b/ref/vk/vk_descriptor.c
@@ -173,7 +173,7 @@ void VK_DescriptorsCreate(vk_descriptors_t *desc)
 
 void VK_DescriptorsWrite(const vk_descriptors_t *desc, int set_slot)
 {
-	VkWriteDescriptorSet wds[16];
+	VkWriteDescriptorSet wds[32];
 	ASSERT(ARRAYSIZE(wds) >= desc->num_bindings);
 	for (int i = 0; i < desc->num_bindings; ++i){
 		const VkDescriptorSetLayoutBinding *binding = desc->bindings + i;