Fix compile error for OpenGL ES

src/framework/graphics/graphics.cpp

@@ -360,9 +360,9 @@ bool Graphics::canUseBlendFuncSeparate()
 bool Graphics::canUseBlendEquation()
 {
 #if OPENGL_ES==2
-    return true;
+    return false;
 #elif OPENGL_ES==1
-    return true;
+    return false;
 #else
     if(!GLEW_VERSION_1_4)
         return false;

src/framework/graphics/painter.cpp

@@ -289,14 +289,7 @@ void Painter::updateGlBlendEquation()
 {
     if(!g_graphics.canUseBlendEquation())
         return;
-    switch(m_blendEquation) {
-        case BlendEquation_Max:
-            glBlendEquation(GL_MAX);
-            break;
-        case BlendEquation_Add:
-            glBlendEquation(GL_FUNC_ADD);
-            break;
-    }
+    glBlendEquation(m_blendEquation);
 }
 
 void Painter::updateGlClipRect()

src/framework/graphics/painter.h

@@ -44,8 +44,8 @@ public:
         TriangleStrip = GL_TRIANGLE_STRIP
     };
     enum BlendEquation {
-        BlendEquation_Add,
-        BlendEquation_Max,
+        BlendEquation_Add = 0x8006, // GL_FUNC_ADD
+        BlendEquation_Max = 0x8008, // GL_MAX
     };
 
     struct PainterState {