From ed919edb0ac5c8eebd77d58176920a5e07d7bf24 Mon Sep 17 00:00:00 2001
From: emil28092005 <emil28092005@users.noreply.github.com>
Date: Thu, 18 Jun 2026 22:00:03 +0300
Subject: [PATCH] =?UTF-8?q?fix:=20enable=20back-face=20culling=20=E2=80=94?=
 =?UTF-8?q?=20removes=20self-shadowing=20artifacts?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Root cause: CULL_MODE_NONE in both main and shadow pipelines caused
back faces to render, creating self-shadowing acne on all objects:
- Shadow map: back faces written at closer depth → false shadows on front
- Main render: back faces visible through objects → wrong lighting

Fix:
- Main pipeline: CULL_MODE_BACK (was None) — only front faces render
- Shadow pipeline: CULL_MODE_BACK (was None) — only front faces cast shadows
- Removed normal flip hack (if dot(N,V) < 0 N = -N) — no longer needed
  with proper culling + correct CCW winding in cube.obj
- This is the standard approach: correct geometry + back-face culling
---
 .../Shaders/triangle.frag                     |   3 ---
 .../Shaders/triangle.frag.spv                 | Bin 13640 -> 13472 bytes
 src/Engine.Graphics.Vulkan/VulkanPipeline.cs  |   2 +-
 src/Engine.Graphics.Vulkan/VulkanShadowMap.cs |   2 +-
 4 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/src/Engine.Graphics.Vulkan/Shaders/triangle.frag b/src/Engine.Graphics.Vulkan/Shaders/triangle.frag
index ed0214b..c80b732 100644
--- a/src/Engine.Graphics.Vulkan/Shaders/triangle.frag
+++ b/src/Engine.Graphics.Vulkan/Shaders/triangle.frag
@@ -138,9 +138,6 @@ void main()
     float dist = length(toLight);
     vec3 L = toLight / max(dist, 0.001);
 
-    // Flip normal to face camera — fixes cubes with bad winding without breaking spheres
-    if (dot(N, V) < 0.0) N = -N;
-
     float attenuation = pow(clamp(1.0 - dist / max(lightRange, 0.001), 0.0, 1.0), 2.0);
     vec3 radiance = lightColor * lightIntensity * attenuation;
 
diff --git a/src/Engine.Graphics.Vulkan/Shaders/triangle.frag.spv b/src/Engine.Graphics.Vulkan/Shaders/triangle.frag.spv
index f615ce72c89730c1d0135a90293100ff4d0addb3..5751d5be87d3802dabf8eff71a86b949c4793a95 100644
GIT binary patch
delta 3413
zcmZ9OS!`8R6o&Wh9a>6@l-pV;(v~zPCK_wviw(5ah;2;_Lhx0So3=uwQ#!zd4@aXW
zCMG20))}>k^MKZ>6cEKIia21MkV!>FP!OEzfaCw2yBD6eIlJfo|F!m7d#|(Cxo78f
z!yU!(yqbLHVs5%CaP!v|FN@6{$y}L=4P{4C>0n*VxxP$WN2a^A-RUps67E51{VOtU
zJ*#tkgLrSIFVp4i4^QEbPT`MF;&JzscuP1p?nZ>0E+B5)jm2D}TfC?#OuBi}q=ef#
zg>Re0<8Hfnvvb+z{0qwy?#(IIUE)pIk^HhC;ohHQOS%umy9c}4`!WMPec`f_Zm+bq
z_U@jpj_y!RYE4I^_4l^74t8d63zvLc+R9})d;+{ESE32w#ce$USNM3R#5+5duNY|T
z=w6<ioNxts&b9V*`lJarQ~dwBCf#iDp22}jy^9hiU1fHCLAs<;7XDWC=2BOW?kGsd
z+L=(9v#1tvhZ~+PdWbe98FB^kA#@bn%qd!pIDgHWS1rH!Ihy06^@Uqgmp`Ws74E62
zKhLEcAx6c~Y@Dm9De3#9Id?;&@x$Wfo5nA)c_*`%l#~b4ltj@Mnpa`SH!L)->Eif=
ze!81qsc`L<qYdU)CXQyKTB|4*k82GFG!}SHq0lOGMXGcMMR2Z?L04EEoZ;2kiIQW%
zkQUBHQ44gZQH)O$r%8-sr%9rmCW&&IB+6-$D5psxJbQ7vI7yzd?9%kyGBVH+=7D8f
zHj`d(HkKVzEOdi;V&9cLl&%WsgQ!X$7$+V*V4PW;|0w6|M>*%;IP>WN<IJZAB0SF(
zWY?CKkB*fN=LH;<+hxB^qh1w;-ywXnMv-R0?-bVM&hfTcBDbm~u-zrhe0*;5+TFq}
z-d3b%hTlEXbm;&&hrM2R`2?qv-0K}GyffYnIwd@QY%GpV+$S7(PT>26uh&?k<k%k&
z#s}RtG%QRU^I0#9-*7C*CE-jVT9Su^J2hAU=Lv4MM}${-8)pk{w#S68^)}8K+-y$>
zukkj{9K0^@<#|%1R;wo&L79vb3*dlbw?Iz|uZ-}G!UVq2SKt|8e9((je5&%Sur7C*
z26p0d&;tw>_<7-8&nfK-!h;%1e2^D~(QNQ+3BF01E_c2LuOs5%OA>x&uv?BT!d9Wp
zF?WqaFyl+Ytcr;=85|pnd0DvM+xQ8B*C{==SA=Kiu7Ke@?8F$$UR_ZeP%GGLy1%Yr
z+1?Pg2SVe*E!$3E%SIE!>-@8NOPEvos_w*OE<WVgt~++i@peo{oGqE~jxY-v^1bq|
zu$&ya_1k;Gy25_LPOlJrw=gz~H7-njvGGoU*ZF7lfpC@P?dFJM#EBnc47SUUg!S8h
zntv?J4sP*_`$QNYbW6HNm^ju;p9-VlOAcOUXy(74X61>Sa6mX(frH}vHPEdBp9$*<
zD}bE}*rGlc-=~3(#r#4zn&Xf-kCrNjuedKoaKd0oz7p0ICcz#}^0hdL@S(3bW#0&+
zAJ$-}dv!;%MI04o_i+5b6_!tMx_`ctfM|nvDE)Ix8k4aT_=xUk7WjK%N{;Qg?r^jH
zAdJSlmsmdvpVUClEkw`%Cy_x7dqMv!%nKUbp5rgVOvXl{6S|{WqF;rhCH_s^O3ZG5
z7sm(PD*T5q=PxWV4tA0!gfUw1KZQwX{4e2N4W2o>`db(ubbA~9Bg|Kx4XftA((%Vm
zynq0FTToVeN5;f)M7N}Q!t112(zrN&==iY9gfNS@swKtoLpPt4Fz;;d6S#Z{IAWl*
zr({I4#6`l<-4=`U;e~EKGlZFE8#qH8KXhX9NsDIwCBkS8E{KQUw+MB<oU?@a)a1L@
zCZpNpv@nx-j#TeVVdW0rdf52dvw7HT-W*}(Ema<>RUtg*D*fZn#JPwX1T^g|ui?5x
aDfwiaCqe-Hv2$Qa$|vN!(edilrT+o-ABXw?

delta 3527
zcmZ9OTWl3o6o&Wo^ppYxDW_U2+7>HVq7jTQHd3OIn~6aPPduKq1uCVjrG*C{MuR3K
zCM0I?j!Ff@3yQT>C`H8>6hTD1fdVRCQAE6OSJeNTvzJVJGOP3d|5|&kz1QqLoz;yy
z?iiNJs~Y57;D)+FH~xWPbArmQ?Ck}?s;H|V6Rr)MYs=O*W}E98oPKGS@1B>octN(l
zWoeGTAl{m7%P#W%7YFc-19(?Io^n0nGvcu+*DE}2B6(A8TcBbyr%a2M4Z1!|xgBy%
z_a)xzmm=To8o+lC;CuS<l>110n$NYbpD*9-@5j^bfOvD*v8bUf+uqU^4@$ek66+h9
zTNX7o$7)(LJ}zx>YeQW}Q<kuJ4JV{6oRh<+z*BNPJ1;!5zNP&(pD!=Zxu(YX3)&l-
z=jX=eyAjgrTAJdT<7xaT2^Sijc9r5S9qqUH7!^#raZzVsrg)q@{Fb!lN>_JpFU$lD
z3@Fce)XJ12jK~>EZbQ;BS0bN6d&7+wpjC<Uo33%yiW`%oIo@46q_5!CEn47^eO0yB
zxB^FtK5;a&t2MMh`Zv;?yZa{N$HYrF?Y+UqosMoUE)9!SMA;@;)X12xnPgEJabhrh
z7I&HOge^xVTioU1Xl9j~MTK}ub2uow(Q_JwR-S88xjQ66@Kti?in~KFygE8re026I
zO`L_I7V6H)F+NzFQ)3)IrzXicHA%iPnw=S)CbB2GGc!8ckeN7@Jlhj-aE?WC97iL`
zIT}g6I|@oFLJokbWZ@7PrzVFW$vFhZiD&;CC!W2Z<m~$-XYU)=_>qnSU;+v9qRx`i
z!PdM{-CZT?^FjhvDsY~xR(*v(D7;X%Qk$I(^blBvzFAtYw1<V!YlTni5k4x+@0@br
zdqjqIM$Zy#xgQgzR+y_5y2nKjCo2gK_*o6I!Q2_lM4k}7Kf#|AzE@VHY2$xNSeL7o
z;TtJi?iaCInDN9c^IB&R=H81qi?pXm^0crnZE)v01z6z>nH5>%{bkaKC78*xJMq~{
z*9nK7llK|nyJRa=oGz~yUPk~9Tj8_9B(k9Agb75a2wNV_ifj;W@;<gZ+<Y$yFY!LM
zKHPjS3&)Rvr2O|lFy|}6D`fciPXe#;-RTydpxIN5q>LqoSk51Q%k!!*`^flf!sNZj
zcVJVXZ9ou?A~m13Y!=q#rpgo$C+^W5-4bmTZuOkjzAoG$o8@!7A&h3mqb2v7(sa3N
zWqkr$gQ3n5%<Oxk>&hksJyEtSGnb_ANMG!Iyb<6vextoBJX|qv>HfA1KRLGPj?X5#
zQ<yg6<E^nXI$V|sVY|fMms#Wo!q)TM!f<@d<U?Vb$sS?2J&(P@>_oDYld;55gZCDG
ztMRe0S{eQ?d?JAdWC#6IVS><YyMHFED?U^BISwS>CydXMe=giB!?#~|c#VG^UkF!d
z9Aox#<_O~bh{INSP?-K1KP1cw?(>KBOJQQrt>{<6<gw%OwJ;j7)Ht9!n#F%BJdZPH
z!gs>S4ty_85W02X2Vq@t2k_GYo79iu{C_3Javl-pp&S26m`7_}4u2LQ2!|CpDy%Cm
zf<Ia07jX&^!`Wd^{3?uoOvXz2Z-Hh-e-mc)aN>U#CPqgjjL*U!B8X<ZCpja3N@Fm7
z5+Bzc%@Us!rseof=ngmE8DTWuujD!_d|HNX6FJB8@9;s)>@Q*7ujh2P=lHiUgYi-5
zl<sI&=pW%^i~ki*wwMnHV$iL_fizK9U9Ud`*iJq#6{jUn2~*H`zIdxR&zx1I#fd?;
zH%@^tADU*%qrK&sxt5_&UixS+zQN*yWat(%M0jnY%209Q(21c{MZ(N>MHEz&hA6|O
z@Y=P;T_iqChEC)7=tZ+CCBn(ITrAF)9lFI_BFs3OZK*JE=;Y+1S=xoy$fXhxaq<BT
zukp<)6XshM-3FssvC+be<tfqJa$&6}ey8E%bJE7)vvFhc=H~{^Rv|iZg`8t#{7kFz
i8VOCi(rbjyQc1o^$BHnXc>HWfidG7b?H*sbwB$c^<e1L@

diff --git a/src/Engine.Graphics.Vulkan/VulkanPipeline.cs b/src/Engine.Graphics.Vulkan/VulkanPipeline.cs
index 6807495..ca3f7a8 100644
--- a/src/Engine.Graphics.Vulkan/VulkanPipeline.cs
+++ b/src/Engine.Graphics.Vulkan/VulkanPipeline.cs
@@ -102,7 +102,7 @@ internal sealed unsafe class VulkanPipeline : IDisposable
                 depthClampEnable = VkBool32.False,
                 rasterizerDiscardEnable = VkBool32.False,
                 polygonMode = VkPolygonMode.Fill,
-                cullMode = VkCullModeFlags.None,
+                cullMode = VkCullModeFlags.Back,
                 frontFace = VkFrontFace.CounterClockwise,
                 depthBiasEnable = VkBool32.False,
                 lineWidth = 1.0f,
diff --git a/src/Engine.Graphics.Vulkan/VulkanShadowMap.cs b/src/Engine.Graphics.Vulkan/VulkanShadowMap.cs
index 66d438b..9617f35 100644
--- a/src/Engine.Graphics.Vulkan/VulkanShadowMap.cs
+++ b/src/Engine.Graphics.Vulkan/VulkanShadowMap.cs
@@ -275,7 +275,7 @@ internal sealed unsafe class VulkanShadowMap : IDisposable
                 depthClampEnable = VkBool32.False,
                 rasterizerDiscardEnable = VkBool32.False,
                 polygonMode = VkPolygonMode.Fill,
-                cullMode = VkCullModeFlags.None,
+                cullMode = VkCullModeFlags.Back,
                 frontFace = VkFrontFace.CounterClockwise,
                 depthBiasEnable = VkBool32.True,
                 lineWidth = 1.0f,