From 4b26830fc1583c96dcbc750cefb257a6e7a07245 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Branimir=20Karad=C5=BEi=C4=87?= <branimirkaradzic@gmail.com>
Date: Fri, 1 Jul 2016 20:38:12 -0700
Subject: [PATCH] shaderc: Allow shader without color target write.

---
 .../15-shadowmaps-simple/fs_sms_shadow.sc     |   1 -
 .../runtime/shaders/dx11/fs_sms_shadow.bin    | Bin 228 -> 148 bytes
 .../runtime/shaders/gles/fs_sms_shadow.bin    | Bin 165 -> 30 bytes
 .../runtime/shaders/glsl/fs_sms_shadow.bin    | Bin 157 -> 30 bytes
 .../runtime/shaders/metal/fs_sms_shadow.bin   | Bin 477 -> 271 bytes
 tools/shaderc/shaderc.cpp                     |  28 +++++++++++++-----
 6 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/examples/15-shadowmaps-simple/fs_sms_shadow.sc b/examples/15-shadowmaps-simple/fs_sms_shadow.sc
index 3cdf1973f..cfaf3412c 100644
--- a/examples/15-shadowmaps-simple/fs_sms_shadow.sc
+++ b/examples/15-shadowmaps-simple/fs_sms_shadow.sc
@@ -7,5 +7,4 @@
 
 void main()
 {
-	gl_FragColor = vec4_splat(0.0);
 }
diff --git a/examples/runtime/shaders/dx11/fs_sms_shadow.bin b/examples/runtime/shaders/dx11/fs_sms_shadow.bin
index 2477d864d9a4d3aea70f3f3593005f0e3bca80d9..2ffc6baeefc6b48e21b978e723207dd6be1fdc29 100644
GIT binary patch
delta 105
zcmaFDIEB&DE!cyF0SsCgTq2yDC08WIc2wPNbYT4P(y>=)5hGBp1&En}SO<s`fVcpN
kJtyXhPYh5{;Q+Eh07M6SxCHS4X$K$%skdWb0BL6c0JRhml>h($

literal 228
zcmZ<@_F!QEgDVU!5l+sEk+;>CF5O>wSEp#9rt9)Aj6k_7K+FupIzXHN#8ZISGuYh^
z#0SZ90I>oPg8+yRQVRn7KpY$vAK)MC8RF^h$Ka1c4@fPVo)E_%ch?Yx)vJR&T!Jis
j@(w`E2gIpBrJoc8fGh?EGoaNlHj@KL1QpmpoWlSB1a=(p

diff --git a/examples/runtime/shaders/gles/fs_sms_shadow.bin b/examples/runtime/shaders/gles/fs_sms_shadow.bin
index 3262874eaf3a193b4806348e2f0b127725fd3a02..81ccc6436e45e09f03be1ed4fe8acb1751ae5517 100644
GIT binary patch
literal 30
gcmZ<@_F!QE1AZV`mY<oTkeis9r=X!}&Bet407$t7EC2ui

literal 165
zcmZ<@_F!QEgK0prEI%_vAvZBIPeDVItC~weAvZN8voyCrp)57oM4=?Npe(T{-q0E-
w0b}b`DA+0(=oz4hRbmmV!Xj3V5KGUAcPmOvch1krF9M3fjJM{h<>F!h07StpH2?qr

diff --git a/examples/runtime/shaders/glsl/fs_sms_shadow.bin b/examples/runtime/shaders/glsl/fs_sms_shadow.bin
index 946d0e83e3be19dd3d4cf1577ec0a0beecb13a92..81ccc6436e45e09f03be1ed4fe8acb1751ae5517 100644
GIT binary patch
literal 30
gcmZ<@_F!QE1AZV`mY<oTkeis9r=X!}&Bet407$t7EC2ui

literal 157
zcmZ<@_F!QEgFYZxmY<oTkeis9r=X$9Rn4WKP?nl(qEM1sP?lH}Z)gn^fU)%|6l@g?
o^bAnMDzS)FVG%1wh^6PmyA>s-JLl)*7Xd|K##?jMa&a*L0DWpI8~^|S

diff --git a/examples/runtime/shaders/metal/fs_sms_shadow.bin b/examples/runtime/shaders/metal/fs_sms_shadow.bin
index b5140b48e9a12dca42ae2a168b56351831fea76b..42cd46cf0c3a601063d5a768ee8cd342e213c680 100644
GIT binary patch
delta 30
hcmcc1+|R`A7VN>o009%Z!zMb4Pwbz}V$H?H003j}215V<

delta 234
zcmeBYy35S%7VN>o00!qKa)*g2D5T}&CzhBfr02xD6(y!S=jY@XSx-z@UC&j`rJzue
zlUU+gk`tVfn37uLUs_U7TA~o2Tapu>Zw-`%YAwkvC`&AgHv|d6*m@NTwh9J%1}I{c
nSj4KZh?N7yY@nJUw&@`|4=4+>24s9uYDsBP9^6^ATwDwQ%5g^#

diff --git a/tools/shaderc/shaderc.cpp b/tools/shaderc/shaderc.cpp
index b5503352c..40873bc55 100644
--- a/tools/shaderc/shaderc.cpp
+++ b/tools/shaderc/shaderc.cpp
@@ -329,11 +329,12 @@ namespace bgfx
 		uint32_t m_size;
 	};
 
-	void strInsert(char* _str, const char* _insert)
+	char* strInsert(char* _str, const char* _insert)
 	{
 		size_t len = strlen(_insert);
 		memmove(&_str[len], _str, strlen(_str) );
 		memcpy(_str, _insert, len);
+		return _str + len;
 	}
 
 	void strReplace(char* _str, const char* _find, const char* _replace)
@@ -1063,7 +1064,7 @@ namespace bgfx
 			char* data;
 			char* input;
 			{
-				const size_t padding = 1024;
+				const size_t padding = 4096;
 				uint32_t size = (uint32_t)bx::getSize(&reader);
 				data = new char[size+padding+1];
 				size = (uint32_t)bx::read(&reader, data, size);
@@ -1463,12 +1464,13 @@ namespace bgfx
 
 						if ('f' == shaderType)
 						{
-							const char* brace = strstr(entry, "{");
-							if (NULL != brace)
+							const char* insert = strstr(entry, "{");
+							if (NULL != insert)
 							{
-								strInsert(const_cast<char*>(brace+1), "\nvec4 bgfx_VoidFrag;\n");
+								insert = strInsert(const_cast<char*>(insert+1), "\nvec4 bgfx_VoidFrag = vec4_splat(0.0);\n");
 							}
 
+							const bool hasFragColor   = NULL != strstr(input, "gl_FragColor");
 							const bool hasFragCoord   = NULL != strstr(input, "gl_FragCoord") || hlsl > 3 || hlsl == 2;
 							const bool hasFragDepth   = NULL != strstr(input, "gl_FragDepth");
 							const bool hasFrontFacing = NULL != strstr(input, "gl_FrontFacing");
@@ -1489,6 +1491,18 @@ namespace bgfx
 								// GL errors when both gl_FragColor and gl_FragData is used.
 								// This will trigger the same error with HLSL compiler too.
 								preprocessor.writef("#define gl_FragColor gl_FragData_0_\n");
+
+								// If it has gl_FragData or gl_FragColor, color target at
+								// index 0 exists, otherwise shader is not modifying color
+								// targets.
+								hasFragData[0] |= hasFragColor || d3d < 11;
+
+								if (NULL != insert
+								&&  d3d < 11
+								&&  !hasFragColor)
+								{
+									insert = strInsert(const_cast<char*>(insert+1), "\ngl_FragColor = bgfx_VoidFrag;\n");
+								}
 							}
 
 							preprocessor.writef("#define void_main()");
@@ -1518,11 +1532,9 @@ namespace bgfx
 								}
 							}
 
-							addFragData(preprocessor, input, 0, arg++ > 0);
-
 							const uint32_t maxRT = d3d > 9 ? BX_COUNTOF(hasFragData) : 4;
 
-							for (uint32_t ii = 1; ii < BX_COUNTOF(hasFragData); ++ii)
+							for (uint32_t ii = 0; ii < BX_COUNTOF(hasFragData); ++ii)
 							{
 								if (ii < maxRT)
 								{