From 1e1158c78b040e1f420faaaa02d30fe154697533 Mon Sep 17 00:00:00 2001
From: kgv <kgv@opencascade.com>
Date: Tue, 15 Dec 2020 00:37:49 +0300
Subject: [PATCH] 0031997: Visualization, TKOpenGl - phong shader compilation
 error with normal texture map enabled

OpenGl_ShaderManager::defaultGlslVersion() now defines GLSL 120 for normal map texture.
---
 src/OpenGl/OpenGl_ShaderManager.cxx | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/OpenGl/OpenGl_ShaderManager.cxx b/src/OpenGl/OpenGl_ShaderManager.cxx
index 3c8f75f89b..844101d3cc 100644
--- a/src/OpenGl/OpenGl_ShaderManager.cxx
+++ b/src/OpenGl/OpenGl_ShaderManager.cxx
@@ -1793,6 +1793,14 @@ int OpenGl_ShaderManager::defaultGlslVersion (const Handle(Graphic3d_ShaderProgr
   }
   else
   {
+    const bool toUseMat2x3 = (theBits & OpenGl_PO_HasTextures) == OpenGl_PO_TextureNormal;
+    if (toUseMat2x3) // TangentSpaceNormal() function uses mat2x3 type
+    {
+      if (myContext->IsGlGreaterEqual (2, 1))
+      {
+        theProgram->SetHeader ("#version 120");
+      }
+    }
     if ((theBits & OpenGl_PO_StippleLine) != 0
      || theProgram->IsPBR())
     {