Route framebuffer texture copies through GL backend

src/util.cpp

@@ -67,6 +67,27 @@ void bind_opengl_sampler(std::uint32_t unit, std::uint32_t sampler) noexcept
     glBindSampler(static_cast<GLuint>(unit), static_cast<GLuint>(sampler));
 }
 
+void copy_opengl_tex_sub_image_2d(
+    std::uint32_t target,
+    std::int32_t level,
+    std::int32_t destination_x,
+    std::int32_t destination_y,
+    std::int32_t source_x,
+    std::int32_t source_y,
+    std::int32_t width,
+    std::int32_t height) noexcept
+{
+    glCopyTexSubImage2D(
+        static_cast<GLenum>(target),
+        static_cast<GLint>(level),
+        static_cast<GLint>(destination_x),
+        static_cast<GLint>(destination_y),
+        static_cast<GLint>(source_x),
+        static_cast<GLint>(source_y),
+        static_cast<GLsizei>(width),
+        static_cast<GLsizei>(height));
+}
+
 }
 
 template<>
@@ -719,6 +740,35 @@ void check_OpenGLError(const char* stmt, const char* fname, int line)
     }
 }
 
+bool copy_framebuffer_to_texture_2d(
+    int destination_x,
+    int destination_y,
+    int source_x,
+    int source_y,
+    int width,
+    int height,
+    int level) noexcept
+{
+    const auto status = pp::renderer::gl::copy_opengl_framebuffer_to_texture_2d(
+        pp::renderer::gl::OpenGlTexture2DFramebufferCopy {
+            .level = level,
+            .destination_x = destination_x,
+            .destination_y = destination_y,
+            .source_x = source_x,
+            .source_y = source_y,
+            .width = width,
+            .height = height,
+        },
+        pp::renderer::gl::OpenGlTexture2DFramebufferCopyDispatch {
+            .copy_tex_sub_image_2d = copy_opengl_tex_sub_image_2d,
+        });
+    if (!status.ok()) {
+        LOG("OpenGL framebuffer-to-texture copy failed: %s", status.message);
+        return false;
+    }
+    return true;
+}
+
 size_t curl_data_handler(void *contents, size_t size, size_t nmemb, void *userp)
 {
     auto buffer = reinterpret_cast<std::string*>(userp);