0032089: Visualization, TKOpenGl - support GL_EXT_sRGB extension to OpenGL ES 2.0

src/OpenGl/OpenGl_Context.cxx

@@ -1557,8 +1557,10 @@ void OpenGl_Context::init (const Standard_Boolean theIsCoreProfile)
 
   hasTexRGBA8 = IsGlGreaterEqual (3, 0)
              || CheckExtension ("GL_OES_rgb8_rgba8");
-  hasTexSRGB  = IsGlGreaterEqual (3, 0);
+  hasTexSRGB  = IsGlGreaterEqual (3, 0)
-  hasFboSRGB  = IsGlGreaterEqual (3, 0);
+             || CheckExtension ("GL_EXT_sRGB");
+  hasFboSRGB  = IsGlGreaterEqual (3, 0)
+             || CheckExtension ("GL_EXT_sRGB");
   hasFboRenderMipmap = IsGlGreaterEqual (3, 0)
                     || CheckExtension ("GL_OES_fbo_render_mipmap");
   hasSRGBControl = CheckExtension ("GL_EXT_sRGB_write_control");
@@ -3355,8 +3357,15 @@ void OpenGl_Context::init (const Standard_Boolean theIsCoreProfile)
       GL_BACK;
     #endif
     GLint aWinColorEncoding = 0; // GL_LINEAR
-    arbFBO->glGetFramebufferAttachmentParameteriv (GL_FRAMEBUFFER, aDefWinBuffer, GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING, &aWinColorEncoding);
+    bool toSkipCheck = false;
-    ResetErrors (true);
+  #ifdef __EMSCRIPTEN__
+    toSkipCheck = !IsGlGreaterEqual (3, 0);
+  #endif
+    if (!toSkipCheck)
+    {
+      arbFBO->glGetFramebufferAttachmentParameteriv (GL_FRAMEBUFFER, aDefWinBuffer, GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING, &aWinColorEncoding);
+      ResetErrors (true);
+    }
     myIsSRgbWindow = aWinColorEncoding == GL_SRGB;
 
     // On desktop OpenGL, pixel formats are almost always sRGB-ready, even when not requested;

src/OpenGl/OpenGl_GLESExtensions.hxx

@@ -33,6 +33,10 @@ typedef double GLclampd;
 // GL_EXT_texture_format_BGRA8888
 #define GL_BGRA_EXT     0x80E1 // same as GL_BGRA on desktop
 
+// GL_EXT_sRGB
+#define GL_SRGB_EXT       0x8C40 // GL_SRGB_EXT
+#define GL_SRGB_ALPHA_EXT 0x8C42 // GL_SRGB_ALPHA_EXT
+
 #define GL_R16          0x822A
 #define GL_RGB4         0x804F
 #define GL_RGB5         0x8050

src/OpenGl/OpenGl_Texture.cxx

@@ -1012,6 +1012,20 @@ bool OpenGl_Texture::InitCubeMap (const Handle(OpenGl_Context)&    theCtx,
     return false;
   }
 
+#if defined(GL_ES_VERSION_2_0)
+  if (theToGenMipmap
+  && !theCtx->IsGlGreaterEqual (3, 0)
+  &&  (aFormat.PixelFormat() == GL_SRGB_EXT
+    || aFormat.PixelFormat() == GL_SRGB_ALPHA_EXT))
+  {
+    theCtx->PushMessage (GL_DEBUG_SOURCE_APPLICATION, GL_DEBUG_TYPE_PORTABILITY, 0, GL_DEBUG_SEVERITY_HIGH,
+                         TCollection_AsciiString ("Warning, GL_EXT_sRGB disallows generation of mipmaps - fallback using non-sRGB format")
+                         + " [" + myResourceId +"]");
+    aFormat.SetPixelFormat   (aFormat.PixelFormat() == GL_SRGB_EXT ? GL_RGB  : GL_RGBA);
+    aFormat.SetInternalFormat(aFormat.PixelFormat() == GL_SRGB_EXT ? GL_RGB8 : GL_RGBA8);
+  }
+#endif
+
   myTarget = GL_TEXTURE_CUBE_MAP;
   myNbSamples = 1;
   mySizeX = (GLsizei )theSize;
@@ -1132,7 +1146,11 @@ bool OpenGl_Texture::InitCubeMap (const Handle(OpenGl_Context)&    theCtx,
     if (anErr != GL_NO_ERROR)
     {
       theCtx->PushMessage (GL_DEBUG_SOURCE_APPLICATION, GL_DEBUG_TYPE_ERROR, 0, GL_DEBUG_SEVERITY_HIGH,
-                           TCollection_AsciiString ("Unable to initialize side of cubemap. Error ") + OpenGl_Context::FormatGlError (anErr));
+                           TCollection_AsciiString ("Error: cubemap side  ") + (int )theSize + "x" + (int )theSize
+                           + " IF: " + OpenGl_TextureFormat::FormatFormat (anIntFormat)
+                           + " PF: " + OpenGl_TextureFormat::FormatFormat (aFormat.PixelFormat())
+                           + " DT: " + OpenGl_TextureFormat::FormatDataType (aFormat.DataType())
+                           + " can not be created with error " + OpenGl_Context::FormatGlError (anErr) + ".");
       Unbind (theCtx);
       Release (theCtx.get());
       return false;

src/OpenGl/OpenGl_TextureFormat.cxx

@@ -46,6 +46,7 @@ TCollection_AsciiString OpenGl_TextureFormat::FormatFormat (GLint theInternalFor
     case 0x8050:      return "GL_RGB5";
     case GL_RGB8:     return "GL_RGB8";
     case GL_SRGB8:    return "GL_SRGB8";
+    case GL_SRGB_EXT: return "GL_SRGB_EXT";
     case 0x8052:      return "GL_RGB10";
     case 0x8053:      return "GL_RGB12";
     case 0x8054:      return "GL_RGB16";
@@ -55,7 +56,8 @@ TCollection_AsciiString OpenGl_TextureFormat::FormatFormat (GLint theInternalFor
     // RGBA variations
     case GL_RGBA:     return "GL_RGBA";
     case GL_RGBA8:    return "GL_RGBA8";
-    case GL_SRGB8_ALPHA8: return "GL_SRGB8_ALPHA8";
+    case GL_SRGB8_ALPHA8:   return "GL_SRGB8_ALPHA8";
+    case GL_SRGB_ALPHA_EXT: return "GL_SRGB_ALPHA_EXT";
     case GL_RGB10_A2: return "GL_RGB10_A2";
     case 0x805A:      return "GL_RGBA12";
     case 0x805B:      return "GL_RGBA16";
@@ -254,6 +256,12 @@ OpenGl_TextureFormat OpenGl_TextureFormat::FindFormat (const Handle(OpenGl_Conte
       if (theIsColorMap
        && theCtx->ToRenderSRGB())
       {
+      #if defined(GL_ES_VERSION_2_0)
+        if (!theCtx->IsGlGreaterEqual (3, 0))
+        {
+          aFormat.SetPixelFormat (GL_SRGB_ALPHA_EXT);
+        }
+      #endif
         aFormat.SetInternalFormat (GL_SRGB8_ALPHA8);
       }
       return aFormat;
@@ -308,6 +316,10 @@ OpenGl_TextureFormat OpenGl_TextureFormat::FindFormat (const Handle(OpenGl_Conte
       if (theIsColorMap
        && theCtx->ToRenderSRGB())
       {
+        if (!theCtx->IsGlGreaterEqual (3, 0))
+        {
+          aFormat.SetPixelFormat (GL_SRGB_ALPHA_EXT);
+        }
         aFormat.SetInternalFormat (GL_SRGB8_ALPHA8);
       }
     #endif
@@ -355,6 +367,12 @@ OpenGl_TextureFormat OpenGl_TextureFormat::FindFormat (const Handle(OpenGl_Conte
       if (theIsColorMap
        && theCtx->ToRenderSRGB())
       {
+      #if defined(GL_ES_VERSION_2_0)
+        if (!theCtx->IsGlGreaterEqual (3, 0))
+        {
+          aFormat.SetPixelFormat (GL_SRGB_EXT);
+        }
+      #endif
         aFormat.SetInternalFormat (GL_SRGB8);
       }
       return aFormat;
@@ -516,6 +534,7 @@ OpenGl_TextureFormat OpenGl_TextureFormat::FindSizedFormat (const Handle(OpenGl_
       return aFormat;
     }
     case GL_SRGB8_ALPHA8:
+    case GL_SRGB_ALPHA_EXT:
     case GL_RGBA8:
     case GL_RGBA:
     {
@@ -524,7 +543,7 @@ OpenGl_TextureFormat OpenGl_TextureFormat::FindSizedFormat (const Handle(OpenGl_
       aFormat.SetPixelFormat (GL_RGBA);
       aFormat.SetDataType (GL_UNSIGNED_BYTE);
       aFormat.SetImageFormat (Image_Format_RGBA);
-      if (theSizedFormat == GL_SRGB8_ALPHA8
+      if ((theSizedFormat == GL_SRGB8_ALPHA8 || theSizedFormat == GL_SRGB_ALPHA_EXT)
       && !theCtx->ToRenderSRGB())
       {
         aFormat.SetInternalFormat (GL_RGBA8); // fallback format
@@ -532,6 +551,7 @@ OpenGl_TextureFormat OpenGl_TextureFormat::FindSizedFormat (const Handle(OpenGl_
       return aFormat;
     }
     case GL_SRGB8:
+    case GL_SRGB_EXT:
     case GL_RGB8:
     case GL_RGB:
     {
@@ -540,7 +560,7 @@ OpenGl_TextureFormat OpenGl_TextureFormat::FindSizedFormat (const Handle(OpenGl_
       aFormat.SetPixelFormat (GL_RGB);
       aFormat.SetDataType (GL_UNSIGNED_BYTE);
       aFormat.SetImageFormat (Image_Format_RGB);
-      if (theSizedFormat == GL_SRGB8
+      if ((theSizedFormat == GL_SRGB8 || theSizedFormat == GL_SRGB_EXT)
       && !theCtx->ToRenderSRGB())
       {
         aFormat.SetInternalFormat (GL_RGB8); // fallback format