d3d10/effect: Fix iteration in GetBackingStore() for blend states.

dlls/d3d10/effect.c

@@ -8555,21 +8555,20 @@ static HRESULT STDMETHODCALLTYPE d3d10_effect_blend_variable_GetBackingStore(ID3
 
     TRACE("iface %p, index %u, desc %p.\n", iface, index, desc);
 
-    if (v->type->element_count)
-        v = impl_from_ID3D10EffectVariable(iface->lpVtbl->GetElement(iface, index));
-
-    if (v->type->basetype != D3D10_SVT_BLEND)
+    if (!iface->lpVtbl->IsValid(iface))
     {
-        WARN("Variable is not a blend state.\n");
+        WARN("Invalid variable.\n");
         return E_FAIL;
     }
 
+    if (!(v = d3d10_get_state_variable(v, index, &v->effect->blend_states)))
+        return E_FAIL;
+
     *desc = v->u.state.desc.blend;
 
     return S_OK;
 }
 
-
 static const struct ID3D10EffectBlendVariableVtbl d3d10_effect_blend_variable_vtbl =
 {
     /* ID3D10EffectVariable methods */

dlls/d3d10/tests/effect.c

@@ -4519,6 +4519,8 @@ static void test_effect_state_groups(void)
             blend_desc.RenderTargetWriteMask[0]);
     ok(blend_desc.RenderTargetWriteMask[7] == 0x7, "Got unexpected RenderTargetWriteMask[7] %#x.\n",
             blend_desc.RenderTargetWriteMask[7]);
+    b->lpVtbl->GetBackingStore(b, 1, &blend_desc);
+    ok(blend_desc.SrcBlend == D3D10_BLEND_SRC_COLOR, "Got unexpected SrcBlend %#x.\n", blend_desc.SrcBlend);
 
     v = effect->lpVtbl->GetVariableByName(effect, "ds_state");
     d = v->lpVtbl->AsDepthStencil(v);