Fixed blitFramebuffer issue with Depth/Stencil

A condition was overly aggressive in producing an INVALID_OPERATION
when the read depth/stencil framebuffer is multisampled. When the
formats are the same and source and destination rectangles are the
same, performing a blitFramebuffer operation is allowed.

Change-Id: I29e52cb546ae1bf248ac0107492c97ea82406613
Reviewed-on: https://swiftshader-review.googlesource.com/8212
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>

src/OpenGL/libGLESv2/Context.cpp

diff --git a/src/OpenGL/libGLESv2/Context.cpp b/src/OpenGL/libGLESv2/Context.cpp
index 0e32336..7ccfc9d 100644
--- a/src/OpenGL/libGLESv2/Context.cpp
+++ b/src/OpenGL/libGLESv2/Context.cpp
@@ -4111,8 +4111,16 @@
 			return error(GL_INVALID_OPERATION);   // Only whole-buffer copies are permitted
 		}
 
+		// OpenGL ES 3.0.4 spec, p.199:
+		// ...an INVALID_OPERATION error is generated if the formats of the read
+		// and draw framebuffers are not identical or if the source and destination 
+		// rectangles are not defined with the same(X0, Y 0) and (X1, Y 1) bounds.
+		// If SAMPLE_BUFFERS for the draw framebuffer is greater than zero, an
+		// INVALID_OPERATION error is generated.
 		if((drawDSBuffer && drawDSBuffer->getSamples() > 1) ||
-		   (readDSBuffer && readDSBuffer->getSamples() > 1))
+		   ((readDSBuffer && readDSBuffer->getSamples() > 1) &&
+		    ((srcX0 != dstX0 || srcY0 != dstY0 || srcX1 != dstX1 || srcY1 != dstY1) ||
+		     (drawDSBuffer->getFormat() != readDSBuffer->getFormat()))))
 		{
 			return error(GL_INVALID_OPERATION);
 		}