From c15439b7cbf0095960882b8c1480a837e35d5047 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Branimir=20Karad=C5=BEi=C4=87?= <branimirkaradzic@gmail.com>
Date: Thu, 9 Apr 2015 20:36:52 -0700
Subject: [PATCH] Added ability to continue when GL shader compilation fails.
 Issue #327.

---
 src/renderer_gl.cpp | 43 ++++++++++++++++++++++++++++---------------
 1 file changed, 28 insertions(+), 15 deletions(-)

diff --git a/src/renderer_gl.cpp b/src/renderer_gl.cpp
index 1f5f3b6a..a619dd84 100644
--- a/src/renderer_gl.cpp
+++ b/src/renderer_gl.cpp
@@ -2853,32 +2853,40 @@ namespace bgfx { namespace gl
 	void ProgramGL::create(const ShaderGL& _vsh, const ShaderGL& _fsh)
 	{
 		m_id = glCreateProgram();
-		BX_TRACE("program create: %d: %d, %d", m_id, _vsh.m_id, _fsh.m_id);
+		BX_TRACE("Program create: GL%d: GL%d, GL%d", m_id, _vsh.m_id, _fsh.m_id);
 
 		const uint64_t id = (uint64_t(_vsh.m_hash)<<32) | _fsh.m_hash;
 		const bool cached = s_renderGL->programFetchFromCache(m_id, id);
 
 		if (!cached)
 		{
-			GL_CHECK(glAttachShader(m_id, _vsh.m_id) );
-
-			if (0 != _fsh.m_id)
-			{
-				GL_CHECK(glAttachShader(m_id, _fsh.m_id) );
-			}
-
-			GL_CHECK(glLinkProgram(m_id) );
-
 			GLint linked = 0;
-			GL_CHECK(glGetProgramiv(m_id, GL_LINK_STATUS, &linked) );
+			if (0 == _vsh.m_id)
+			{
+				GL_CHECK(glAttachShader(m_id, _vsh.m_id) );
+
+				if (0 != _fsh.m_id)
+				{
+					GL_CHECK(glAttachShader(m_id, _fsh.m_id) );
+				}
+
+				GL_CHECK(glLinkProgram(m_id) );
+				GL_CHECK(glGetProgramiv(m_id, GL_LINK_STATUS, &linked) );
+
+				if (0 == linked)
+				{
+					char log[1024];
+					GL_CHECK(glGetProgramInfoLog(m_id, sizeof(log), NULL, log) );
+					BX_TRACE("%d: %s", linked, log);
+				}
+			}
 
 			if (0 == linked)
 			{
-				char log[1024];
-				GL_CHECK(glGetProgramInfoLog(m_id, sizeof(log), NULL, log) );
-				BX_TRACE("%d: %s", linked, log);
-
+				BX_WARN(0 != _vsh.m_id, "Invalid vertex/compute shader.");
 				GL_CHECK(glDeleteProgram(m_id) );
+				m_used[0] = Attrib::Count;
+				m_id = 0;
 				return;
 			}
 
@@ -4188,6 +4196,7 @@ namespace bgfx { namespace gl
 				BX_TRACE("Failed to compile shader. %d: %s", compiled, log);
 
 				GL_CHECK(glDeleteShader(m_id) );
+				m_id = 0;
 				BGFX_FATAL(false, bgfx::Fatal::InvalidShader, "Failed to compile shader.");
 			}
 			else if (BX_ENABLED(BGFX_CONFIG_DEBUG)
@@ -5052,6 +5061,10 @@ namespace bgfx { namespace gl
 				{
 					programIdx = key.m_program;
 					GLuint id = invalidHandle == programIdx ? 0 : m_program[programIdx].m_id;
+
+					// Skip rendering if program index is valid, but program is invalid.
+					programIdx = 0 == id ? invalidHandle : programIdx;
+
 					GL_CHECK(glUseProgram(id) );
 					programChanged =
 						constantsChanged =