From 5c225e8e077074d0f1fc3309ce148d13225ec023 Mon Sep 17 00:00:00 2001
From: iko <iko@opencascade.com>
Date: Thu, 12 Sep 2019 16:07:30 +0300
Subject: [PATCH] 0030963: Visualization, TKOpenGl - texture unit error during
 FFP global texture's parameters processing

The texture units used in FFP texture functions are correct now.
---
 src/OpenGl/OpenGl_Context.cxx | 22 ++++++++++++----------
 src/OpenGl/OpenGl_Context.hxx |  6 ++++++
 src/OpenGl/OpenGl_Sampler.cxx |  3 ++-
 3 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/src/OpenGl/OpenGl_Context.cxx b/src/OpenGl/OpenGl_Context.cxx
index d22993dc01..702ed31aaf 100644
--- a/src/OpenGl/OpenGl_Context.cxx
+++ b/src/OpenGl/OpenGl_Context.cxx
@@ -162,6 +162,7 @@ OpenGl_Context::OpenGl_Context (const Handle(OpenGl_Caps)& theCaps)
   myTexClamp   (GL_CLAMP_TO_EDGE),
   myMaxTexDim  (1024),
   myMaxTexCombined (1),
+  myMaxTexUnitsFFP (1),
   myMaxDumpSizeX (1024),
   myMaxDumpSizeY (1024),
   myMaxClipPlanes (6),
@@ -1557,18 +1558,19 @@ void OpenGl_Context::init (const Standard_Boolean theIsCoreProfile)
   }
 
   glGetIntegerv (GL_MAX_TEXTURE_SIZE, &myMaxTexDim);
+#if !defined(GL_ES_VERSION_2_0)
+  if (IsGlGreaterEqual (1, 3) && core11 != NULL)
+  {
+    // this is a maximum of texture units for FFP functionality,
+    // usually smaller than combined texture units available for GLSL
+    glGetIntegerv (GL_MAX_TEXTURE_UNITS, &myMaxTexUnitsFFP);
+    myMaxTexCombined = myMaxTexUnitsFFP;
+  }
+#endif
   if (IsGlGreaterEqual (2, 0))
   {
     glGetIntegerv (GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS, &myMaxTexCombined);
   }
-#if !defined(GL_ES_VERSION_2_0)
-  else if (IsGlGreaterEqual (1, 3))
-  {
-    // this is a maximum of texture units for FFP functionality,
-    // dramatically smaller than combined texture units available for GLSL
-    glGetIntegerv (GL_MAX_TEXTURE_UNITS, &myMaxTexCombined);
-  }
-#endif
   mySpriteTexUnit = myMaxTexCombined >= 2
                   ? Graphic3d_TextureUnit_1
                   : Graphic3d_TextureUnit_0;
@@ -3233,13 +3235,13 @@ Handle(OpenGl_TextureSet) OpenGl_Context::BindTextures (const Handle(OpenGl_Text
       {
         if (const Handle(OpenGl_Texture)& aTextureOld = aTextureIterOld.Value())
         {
+          aTextureOld->Unbind(aThisCtx);
         #if !defined(GL_ES_VERSION_2_0)
           if (core11 != NULL)
           {
             OpenGl_Sampler::resetGlobalTextureParams (aThisCtx, *aTextureOld, aTextureOld->Sampler()->Parameters());
           }
         #endif
-          aTextureOld->Unbind (aThisCtx);
         }
       }
       break;
@@ -3260,13 +3262,13 @@ Handle(OpenGl_TextureSet) OpenGl_Context::BindTextures (const Handle(OpenGl_Text
       {
         if (!aTextureOld.IsNull())
         {
+          aTextureOld->Unbind(aThisCtx);
         #if !defined(GL_ES_VERSION_2_0)
           if (core11 != NULL)
           {
             OpenGl_Sampler::resetGlobalTextureParams (aThisCtx, *aTextureOld, aTextureOld->Sampler()->Parameters());
           }
         #endif
-          aTextureOld->Unbind (aThisCtx);
         }
 
         aTextureIterNew.Next();
diff --git a/src/OpenGl/OpenGl_Context.hxx b/src/OpenGl/OpenGl_Context.hxx
index 187416bedc..6c7f256a11 100644
--- a/src/OpenGl/OpenGl_Context.hxx
+++ b/src/OpenGl/OpenGl_Context.hxx
@@ -497,6 +497,11 @@ public:
   //! @return value for GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS
   Standard_Integer MaxCombinedTextureUnits() const { return myMaxTexCombined; }
 
+  //! This method returns the multi-texture limit for obsolete fixed-function pipeline.
+  //! Use MaxCombinedTextureUnits() instead for limits for using programmable pipeline.
+  //! @return value for GL_MAX_TEXTURE_UNITS
+  Standard_Integer MaxTextureUnitsFFP() const { return myMaxTexUnitsFFP; }
+
   //! @return texture unit to be used for sprites
   Graphic3d_TextureUnit SpriteTextureUnit() const { return mySpriteTexUnit; }
 
@@ -965,6 +970,7 @@ private: // context info
   Standard_Integer myTexClamp;             //!< either GL_CLAMP_TO_EDGE (1.2+) or GL_CLAMP (1.1)
   Standard_Integer myMaxTexDim;            //!< value for GL_MAX_TEXTURE_SIZE
   Standard_Integer myMaxTexCombined;       //!< value for GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS
+  Standard_Integer myMaxTexUnitsFFP;       //!< value for GL_MAX_TEXTURE_UNITS (fixed-function pipeline only)
   Standard_Integer myMaxDumpSizeX;         //!< maximum FBO width  for image dump
   Standard_Integer myMaxDumpSizeY;         //!< maximum FBO height for image dump
   Standard_Integer myMaxClipPlanes;        //!< value for GL_MAX_CLIP_PLANES
diff --git a/src/OpenGl/OpenGl_Sampler.cxx b/src/OpenGl/OpenGl_Sampler.cxx
index 4ee9e5b576..24b69b65fa 100644
--- a/src/OpenGl/OpenGl_Sampler.cxx
+++ b/src/OpenGl/OpenGl_Sampler.cxx
@@ -276,7 +276,8 @@ void OpenGl_Sampler::applyGlobalTextureParams (const Handle(OpenGl_Context)& the
   (void )theTexture;
   (void )theParams;
 #else
-  if (theCtx->core11 == NULL)
+  if (theCtx->core11 == NULL
+   || theParams->TextureUnit() >= theCtx->MaxTextureUnitsFFP())
   {
     return;
   }