BGE Bugfix for [#22371] Alpha Planes affecting 2DFilters

disabling GL_Blend at the 2dfilter drawing routine makes the trick here. there is not a clear function invoked before the 2dfilter drawing routine. Therefore I found better to disable alpha blending while we are setting the other OpenGl attributes/matrixes.

We are not re-enabling GL_BLEND after we disable it. We could and it wouldn't hurt but I can't see why to. open to suggestions here of course.

source/gameengine/Rasterizer/RAS_2DFilterManager.cpp

@@ -431,6 +431,8 @@ void RAS_2DFilterManager::RenderFilters(RAS_ICanvas* canvas)
 	glViewport(0,0, texturewidth, textureheight);
 
 	glDisable(GL_DEPTH_TEST);
+	// if the last rendered face had alpha add it would messes with the color of the plane we apply 2DFilter to
+	glDisable(GL_BLEND); 
 	glPushMatrix();		//GL_MODELVIEW
 	glLoadIdentity();	// GL_MODELVIEW
 	glMatrixMode(GL_TEXTURE);