Route default clear through renderer GL

src/renderer_gl/opengl_capabilities.cpp

@@ -261,6 +261,26 @@ pp::foundation::Result<OpenGlRuntimeInfo> query_opengl_runtime_info(
     });
 }
 
+OpenGlDefaultClear panopainter_default_clear() noexcept
+{
+    return OpenGlDefaultClear {
+        .color = { 0.1F, 0.1F, 0.1F, 1.0F },
+        .mask = framebuffer_color_buffer_mask(),
+    };
+}
+
+pp::foundation::Status clear_panopainter_default_target(OpenGlClearDispatch dispatch) noexcept
+{
+    if (dispatch.clear_color == nullptr || dispatch.clear == nullptr) {
+        return pp::foundation::Status::invalid_argument("OpenGL clear dispatch callbacks must not be null");
+    }
+
+    const auto clear = panopainter_default_clear();
+    dispatch.clear_color(clear.color[0], clear.color[1], clear.color[2], clear.color[3]);
+    dispatch.clear(clear.mask);
+    return pp::foundation::Status::success();
+}
+
 std::uint32_t extension_count_query() noexcept
 {
     return gl_num_extensions;