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;

src/renderer_gl/opengl_capabilities.h

@@ -148,6 +148,19 @@ struct OpenGlRuntimeInfoDispatch {
     OpenGlStringQueryFn get_string = nullptr;
 };
 
+struct OpenGlDefaultClear {
+    std::array<float, 4> color {};
+    std::uint32_t mask = 0;
+};
+
+using OpenGlClearColorFn = void (*)(float r, float g, float b, float a) noexcept;
+using OpenGlClearFn = void (*)(std::uint32_t mask) noexcept;
+
+struct OpenGlClearDispatch {
+    OpenGlClearColorFn clear_color = nullptr;
+    OpenGlClearFn clear = nullptr;
+};
+
 [[nodiscard]] OpenGlCapabilities detect_opengl_capabilities(
     std::span<const std::string_view> extensions,
     OpenGlRuntime runtime) noexcept;
@@ -157,6 +170,8 @@ struct OpenGlRuntimeInfoDispatch {
 [[nodiscard]] pp::foundation::Status apply_panopainter_initial_state(OpenGlStateDispatch dispatch) noexcept;
 [[nodiscard]] pp::foundation::Result<OpenGlRuntimeInfo> query_opengl_runtime_info(
     OpenGlRuntimeInfoDispatch dispatch) noexcept;
+[[nodiscard]] OpenGlDefaultClear panopainter_default_clear() noexcept;
+[[nodiscard]] pp::foundation::Status clear_panopainter_default_target(OpenGlClearDispatch dispatch) noexcept;
 
 [[nodiscard]] std::uint32_t extension_count_query() noexcept;
 [[nodiscard]] std::uint32_t extension_string_name() noexcept;