feat(rendering): add RenderPicker plugin

CHANGELOG.md

@@ -29,6 +29,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Addition and removal of resources through Commands (#325, **@RiscadoA**).
 - Access to unscaled delta time for utilities like the debug camera (#1020, **@RiscadoA**).
 - RenderTarget plugin (#1059, **@tomas7770**).
+- RenderPicker plugin (#1060, **@tomas7770**).
 
 ### Changed
 

engine/CMakeLists.txt

@@ -109,6 +109,9 @@ set(CUBOS_ENGINE_SOURCE
 
 	"src/render/target/plugin.cpp"
 	"src/render/target/target.cpp"
+
+	"src/render/picker/plugin.cpp"
+	"src/render/picker/picker.cpp"
 )
 
 # Create cubos engine

engine/include/cubos/engine/render/picker/picker.hpp

@@ -0,0 +1,33 @@
+/// @file
+/// @brief Component @ref cubos::engine::RenderPicker.
+/// @ingroup render-picker-plugin
+
+#pragma once
+
+#include <glm/vec2.hpp>
+
+#include <cubos/core/gl/render_device.hpp>
+#include <cubos/core/reflection/reflect.hpp>
+
+namespace cubos::engine
+{
+    /// @brief Component which provides a texture to store entity/gizmo ids, for selection with a mouse.
+    /// @ingroup render-picker-plugin
+    struct RenderPicker
+    {
+        CUBOS_REFLECT;
+
+        /// @brief Size of the RenderPicker textures, in pixels.
+        glm::uvec2 size = {0, 0};
+
+        /// @brief Picking back texture, stores entity/gizmo ids for each pixel on the screen. Access to the
+        /// picker results should be made through this texture, to ensure the CPU doesn't wait for the current frame
+        /// to finish.
+        core::gl::Texture2D backTexture{nullptr};
+
+        /// @brief Picking front texture, stores entity/gizmo ids for each pixel on the screen. This is the texture
+        /// used by the renderer to write ids. It is automatically swapped with the back texture by the
+        /// renderPickerPlugin.
+        core::gl::Texture2D frontTexture{nullptr};
+    };
+} // namespace cubos::engine

engine/include/cubos/engine/render/picker/plugin.hpp

@@ -0,0 +1,32 @@
+/// @dir
+/// @brief @ref render-picker-plugin plugin directory.
+
+/// @file
+/// @brief Plugin entry point.
+/// @ingroup render-picker-plugin
+
+#pragma once
+
+#include <cubos/engine/prelude.hpp>
+
+namespace cubos::engine
+{
+    /// @defgroup render-picker-plugin RenderPicker
+    /// @ingroup render-plugins
+    /// @brief Adds and manages @ref RenderPicker components.
+    ///
+    /// ## Dependencies
+    /// - @ref window-plugin
+    /// - @ref render-target-plugin
+
+    /// @brief Recreates the RenderPicker if necessary - for example, due to a render target resize.
+    extern Tag createRenderPickerTag;
+
+    /// @brief Systems which draw to RenderPicker textures should be tagged with this.
+    extern Tag drawToRenderPickerTag;
+
+    /// @brief Plugin entry function.
+    /// @param cubos @b CUBOS. main class.
+    /// @ingroup render-picker-plugin
+    void renderPickerPlugin(Cubos& cubos);
+} // namespace cubos::engine

engine/src/render/picker/picker.cpp

@@ -0,0 +1,12 @@
+#include <cubos/core/ecs/reflection.hpp>
+#include <cubos/core/reflection/external/glm.hpp>
+#include <cubos/core/reflection/external/primitives.hpp>
+
+#include <cubos/engine/render/picker/picker.hpp>
+
+CUBOS_REFLECT_IMPL(cubos::engine::RenderPicker)
+{
+    return core::ecs::TypeBuilder<RenderPicker>("cubos::engine::RenderPicker")
+        .withField("size", &RenderPicker::size)
+        .build();
+}

engine/src/render/picker/plugin.cpp

@@ -0,0 +1,56 @@
+#include <cubos/core/io/window.hpp>
+#include <cubos/core/reflection/external/primitives.hpp>
+
+#include <cubos/engine/render/picker/picker.hpp>
+#include <cubos/engine/render/picker/plugin.hpp>
+#include <cubos/engine/render/target/plugin.hpp>
+#include <cubos/engine/render/target/target.hpp>
+#include <cubos/engine/window/plugin.hpp>
+
+using cubos::core::gl::Texture2DDesc;
+using cubos::core::gl::TextureFormat;
+using cubos::core::gl::Usage;
+using cubos::core::io::Window;
+
+CUBOS_DEFINE_TAG(cubos::engine::createRenderPickerTag);
+CUBOS_DEFINE_TAG(cubos::engine::drawToRenderPickerTag);
+
+void cubos::engine::renderPickerPlugin(Cubos& cubos)
+{
+    cubos.depends(windowPlugin);
+    cubos.depends(renderTargetPlugin);
+
+    cubos.component<RenderPicker>();
+
+    cubos.tag(createRenderPickerTag).after(resizeRenderTargetTag);
+    cubos.tag(drawToRenderPickerTag).after(createRenderPickerTag);
+
+    cubos.system("resize RenderPickers")
+        .tagged(createRenderPickerTag)
+        .call([](const Window& window, Query<const RenderTarget&, RenderPicker&> query) {
+            for (auto [target, renderPicker] : query)
+            {
+                if (target.size != renderPicker.size)
+                {
+                    renderPicker.size = target.size;
+
+                    // Prepare common texture description.
+                    Texture2DDesc desc{};
+                    desc.width = renderPicker.size.x;
+                    desc.height = renderPicker.size.y;
+                    desc.usage = Usage::Dynamic;
+                    desc.format = TextureFormat::RG16UInt;
+
+                    auto& rd = window->renderDevice();
+
+                    renderPicker.backTexture = rd.createTexture2D(desc);
+                    renderPicker.frontTexture = rd.createTexture2D(desc);
+
+                    CUBOS_INFO("Resized RenderPicker to {}x{}", renderPicker.size.x, renderPicker.size.y);
+                }
+
+                // Swap textures
+                std::swap(renderPicker.backTexture, renderPicker.frontTexture);
+            }
+        });
+}