feat(rendering): add splitscreen plugin

engine/CMakeLists.txt

@@ -77,6 +77,9 @@ set(CUBOS_ENGINE_SOURCE
     "src/cubos/engine/renderer/pps/copy_pass.cpp"
     "src/cubos/engine/renderer/pps/manager.cpp"
     "src/cubos/engine/renderer/pps/pass.cpp"
+    "src/cubos/engine/renderer/viewport.cpp"
+
+    "src/cubos/engine/splitscreen/plugin.cpp"
 )
 
 # Create cubos engine

engine/include/cubos/engine/renderer/plugin.hpp

@@ -48,6 +48,7 @@ namespace cubos::engine
     /// ## Components
     /// - @ref RenderableGrid - a grid to be rendered.
     /// - @ref Camera - holds camera information.
+    /// - @ref Viewport - holds viewport information.
     /// - @ref SpotLight - emits a spot light.
     /// - @ref DirectionalLight - emits a directional light.
     /// - @ref PointLight - emits a point light.

engine/include/cubos/engine/renderer/viewport.hpp

@@ -0,0 +1,25 @@
+/// @file
+/// @brief Component @ref cubos::engine::Viewport.
+/// @ingroup renderer-plugin
+
+#pragma once
+
+#include <glm/vec2.hpp>
+
+#include <cubos/core/reflection/reflect.hpp>
+
+namespace cubos::engine
+{
+    /// @brief Component which defines parameters of a viewport, the actual screen space
+    /// that will be used by the camera it is attached to. Useful for having multiple camera views
+    /// shown on screen.
+    /// @note Should be used with @ref LocalToWorld.
+    /// @ingroup renderer-plugin
+    struct Viewport
+    {
+        CUBOS_REFLECT;
+
+        glm::ivec2 position{0.0F, 0.0F}; //< Top left position of the viewport in pixels
+        glm::ivec2 size{0.0F, 0.0F};     //< Size of the viewport in pixels
+    };
+} // namespace cubos::engine

engine/include/cubos/engine/splitscreen/plugin.hpp

@@ -0,0 +1,25 @@
+/// @dir
+/// @brief @ref splitscreen-plugin plugin directory.
+
+/// @file
+/// @brief Plugin entry point.
+/// @ingroup splitscreen-plugin
+
+#pragma once
+
+#include <cubos/engine/cubos.hpp>
+
+namespace cubos::engine
+{
+    /// @defgroup splitscreen-plugin Splitscreen
+    /// @ingroup engine
+    /// @brief Adds viewport to all active cameras to achieve a splitscreen layout.
+    ///
+    /// ## Dependencies
+    /// - @ref renderer-plugin
+
+    /// @brief Plugin entry function.
+    /// @param cubos @b CUBOS. main class
+    /// @ingroup splitscreen-plugin
+    void splitscreenPlugin(Cubos& cubos);
+} // namespace cubos::engine

engine/samples/renderer/main.cpp

@@ -2,6 +2,7 @@
 #include <cubos/engine/renderer/plugin.hpp>
 #include <cubos/engine/renderer/point_light.hpp>
 #include <cubos/engine/settings/settings.hpp>
+#include <cubos/engine/splitscreen/plugin.hpp>
 #include <cubos/engine/transform/plugin.hpp>
 
 using namespace cubos::engine;
@@ -66,9 +67,19 @@ static void spawnCamerasSystem(Commands commands, Write<ActiveCameras> camera)
             .add(Rotation{glm::quatLookAt(glm::normalize(glm::vec3{1.0F, 0.0F, 1.0F}), glm::vec3{0.0F, 1.0F, 0.0F})})
             .entity();
 
-    // Add two other viewports using the same camera, which splits the screen in three.
-    camera->entities[1] = camera->entities[0];
-    camera->entities[2] = camera->entities[0];
+    camera->entities[1] =
+        commands.create()
+            .add(Camera{.fovY = 60.0F, .zNear = 0.1F, .zFar = 100.0F})
+            .add(Position{{-3.0, 1.0F, -3.0F}})
+            .add(Rotation{glm::quatLookAt(glm::normalize(glm::vec3{1.0F, 0.0F, 1.0F}), glm::vec3{0.0F, 1.0F, 0.0F})})
+            .entity();
+
+    camera->entities[2] =
+        commands.create()
+            .add(Camera{.fovY = 60.0F, .zNear = 0.1F, .zFar = 100.0F})
+            .add(Position{{-3.0, 1.0F, -3.0F}})
+            .add(Rotation{glm::quatLookAt(glm::normalize(glm::vec3{1.0F, 0.0F, 1.0F}), glm::vec3{0.0F, 1.0F, 0.0F})})
+            .entity();
 }
 /// [Spawn the cameras]
 
@@ -77,6 +88,7 @@ int main()
     Cubos cubos{};
 
     /// [Adding the plugin]
+    cubos.addPlugin(splitscreenPlugin);
     cubos.addPlugin(rendererPlugin);
     /// [Adding the plugin]
 

engine/samples/voxels/main.cpp

@@ -1,77 +1,77 @@
-#include <cubos/engine/renderer/directional_light.hpp>
-#include <cubos/engine/renderer/plugin.hpp>
-#include <cubos/engine/settings/settings.hpp>
-#include <cubos/engine/transform/plugin.hpp>
-#include <cubos/engine/voxels/plugin.hpp>
-
-using namespace cubos::engine;
-
-/// [Get handles to assets]
-static const Asset<VoxelGrid> CarAsset = AnyAsset("059c16e7-a439-44c7-9bdc-6e069dba0c75");
-static const Asset<VoxelPalette> PaletteAsset = AnyAsset("1aa5e234-28cb-4386-99b4-39386b0fc215");
-/// [Get handles to assets]
-
-static void settingsSystem(Write<Settings> settings)
-{
-    settings->setString("assets.io.path", SAMPLE_ASSETS_FOLDER);
-}
-
-/// [Load and set palette]
-static void setPaletteSystem(Read<Assets> assets, Write<Renderer> renderer)
-{
-    // Read the palette's data and pass it to the renderer.
-    auto palette = assets->read(PaletteAsset);
-    (*renderer)->setPalette(*palette);
-}
-/// [Load and set palette]
-
-static void spawnCameraSystem(Commands cmds, Write<ActiveCameras> activeCameras)
-{
-    // Spawn the camera entity.
-    activeCameras->entities[0] =
-        cmds.create()
-            .add(Camera{.fovY = 60.0F, .zNear = 0.1F, .zFar = 1000.0F})
-            .add(Position{{50.0F, 50.0F, 50.0F}})
-            .add(Rotation{glm::quatLookAt(glm::normalize(glm::vec3{-1.0F, -1.0F, -1.0F}), glm::vec3{0.0F, 1.0F, 0.0F})})
-            .entity();
-}
-
-static void spawnLightSystem(Commands cmds)
-{
-    // Spawn the sun.
-    cmds.create()
-        .add(DirectionalLight{glm::vec3(1.0F), 1.0F})
-        .add(Rotation{glm::quat(glm::vec3(glm::radians(45.0F), glm::radians(45.0F), 0))});
-}
-
-/// [Spawn car system]
-static void spawnCarSystem(Commands cmds, Read<Assets> assets)
-{
-    // Calculate the necessary offset to center the model on (0, 0, 0).
-    auto car = assets->read(CarAsset);
-    glm::vec3 offset = glm::vec3(car->size().x, 0.0F, car->size().z) / -2.0F;
-
-    // Create the car entity
-    cmds.create().add(RenderableGrid{CarAsset, offset}).add(LocalToWorld{});
-}
-/// [Spawn car system]
-
-int main(int argc, char** argv)
-{
-    Cubos cubos{argc, argv};
-
-    cubos.addPlugin(rendererPlugin);
-    /// [Adding the plugin]
-    cubos.addPlugin(voxelsPlugin);
-    /// [Adding the plugin]
-
-    cubos.startupSystem(settingsSystem).tagged("cubos.settings");
-    cubos.startupSystem(spawnCameraSystem);
-    cubos.startupSystem(spawnLightSystem);
-    /// [Adding systems]
-    cubos.startupSystem(setPaletteSystem).after("cubos.renderer.init");
-    cubos.startupSystem(spawnCarSystem).tagged("cubos.assets");
-    /// [Adding systems]
-
-    cubos.run();
+#include <cubos/engine/renderer/directional_light.hpp>
+#include <cubos/engine/renderer/plugin.hpp>
+#include <cubos/engine/settings/settings.hpp>
+#include <cubos/engine/transform/plugin.hpp>
+#include <cubos/engine/voxels/plugin.hpp>
+
+using namespace cubos::engine;
+
+/// [Get handles to assets]
+static const Asset<VoxelGrid> CarAsset = AnyAsset("059c16e7-a439-44c7-9bdc-6e069dba0c75");
+static const Asset<VoxelPalette> PaletteAsset = AnyAsset("1aa5e234-28cb-4386-99b4-39386b0fc215");
+/// [Get handles to assets]
+
+static void settingsSystem(Write<Settings> settings)
+{
+    settings->setString("assets.io.path", SAMPLE_ASSETS_FOLDER);
+}
+
+/// [Load and set palette]
+static void setPaletteSystem(Read<Assets> assets, Write<Renderer> renderer)
+{
+    // Read the palette's data and pass it to the renderer.
+    auto palette = assets->read(PaletteAsset);
+    (*renderer)->setPalette(*palette);
+}
+/// [Load and set palette]
+
+static void spawnCameraSystem(Commands cmds, Write<ActiveCameras> activeCameras)
+{
+    // Spawn the camera entity.
+    activeCameras->entities[0] =
+        cmds.create()
+            .add(Camera{.fovY = 60.0F, .zNear = 0.1F, .zFar = 1000.0F})
+            .add(Position{{50.0F, 50.0F, 50.0F}})
+            .add(Rotation{glm::quatLookAt(glm::normalize(glm::vec3{-1.0F, -1.0F, -1.0F}), glm::vec3{0.0F, 1.0F, 0.0F})})
+            .entity();
+}
+
+static void spawnLightSystem(Commands cmds)
+{
+    // Spawn the sun.
+    cmds.create()
+        .add(DirectionalLight{glm::vec3(1.0F), 1.0F})
+        .add(Rotation{glm::quat(glm::vec3(glm::radians(45.0F), glm::radians(45.0F), 0))});
+}
+
+/// [Spawn car system]
+static void spawnCarSystem(Commands cmds, Read<Assets> assets)
+{
+    // Calculate the necessary offset to center the model on (0, 0, 0).
+    auto car = assets->read(CarAsset);
+    glm::vec3 offset = glm::vec3(car->size().x, 0.0F, car->size().z) / -2.0F;
+
+    // Create the car entity
+    cmds.create().add(RenderableGrid{CarAsset, offset}).add(LocalToWorld{});
+}
+/// [Spawn car system]
+
+int main(int argc, char** argv)
+{
+    Cubos cubos{argc, argv};
+
+    cubos.addPlugin(rendererPlugin);
+    /// [Adding the plugin]
+    cubos.addPlugin(voxelsPlugin);
+    /// [Adding the plugin]
+
+    cubos.startupSystem(settingsSystem).tagged("cubos.settings");
+    cubos.startupSystem(spawnCameraSystem);
+    cubos.startupSystem(spawnLightSystem);
+    /// [Adding systems]
+    cubos.startupSystem(setPaletteSystem).after("cubos.renderer.init");
+    cubos.startupSystem(spawnCarSystem).tagged("cubos.assets");
+    /// [Adding systems]
+
+    cubos.run();
 }

engine/src/cubos/engine/renderer/plugin.cpp

@@ -10,6 +10,7 @@
 #include <cubos/engine/renderer/point_light.hpp>
 #include <cubos/engine/renderer/pps/bloom.hpp>
 #include <cubos/engine/renderer/spot_light.hpp>
+#include <cubos/engine/renderer/viewport.hpp>
 #include <cubos/engine/settings/plugin.hpp>
 #include <cubos/engine/transform/plugin.hpp>
 #include <cubos/engine/window/plugin.hpp>
@@ -113,42 +114,8 @@ static void checkPaletteUpdateSystem(Write<Assets> assets, Write<Renderer> rende
     }
 }
 
-/// @brief Splits the viewport recursively for the given cameras.
-/// @param position Viewport position.
-/// @param size Viewport size.
-/// @param count How many cameras need to be fitted in to the given viewport.
-/// @param viewport Output array where the viewports will be set.
-static void splitViewport(glm::ivec2 position, glm::ivec2 size, int count, BaseRenderer::Viewport* viewports)
-{
-    if (count == 1)
-    {
-        viewports[0].position = position;
-        viewports[0].size = size;
-    }
-    else if (count >= 2)
-    {
-        glm::ivec2 splitSize;
-        glm::ivec2 splitOffset;
-
-        // Split along the largest axis.
-        if (size.x > size.y)
-        {
-            splitSize = {size.x / 2, size.y};
-            splitOffset = {size.x / 2, 0};
-        }
-        else
-        {
-            splitSize = {size.x, size.y / 2};
-            splitOffset = {0, size.y / 2};
-        }
-
-        splitViewport(position, splitSize, count / 2, viewports);
-        splitViewport(position + splitOffset, splitSize, (count + 1) / 2, &viewports[count / 2]);
-    }
-}
-
 static void draw(Write<Renderer> renderer, Read<ActiveCameras> activeCameras, Write<RendererFrame> frame,
-                 Query<Read<LocalToWorld>, Read<Camera>> query)
+                 Query<Read<LocalToWorld>, Read<Camera>, OptRead<Viewport>> query)
 {
     Camera cameras[4]{};
     glm::mat4 views[4]{};
@@ -165,17 +132,25 @@ static void draw(Write<Renderer> renderer, Read<ActiveCameras> activeCameras, Wr
 
         if (auto components = query[activeCameras->entities[i]])
         {
-            auto [localToWorld, camera] = *components;
+            auto [localToWorld, camera, viewport] = *components;
             cameras[cameraCount].fovY = camera->fovY;
             cameras[cameraCount].zNear = camera->zNear;
             cameras[cameraCount].zFar = camera->zFar;
+            if (viewport)
+            {
+                viewports[i].position = viewport->position;
+                viewports[i].size = viewport->size;
+            }
+            else
+            {
+                viewports[i].position = {0, 0};
+                viewports[i].size = (*renderer)->size();
+            }
             views[cameraCount] = glm::inverse(localToWorld->mat);
             cameraCount += 1;
         }
     }
 
-    splitViewport({0, 0}, (*renderer)->size(), cameraCount, viewports);
-
     if (cameraCount == 0)
     {
         CUBOS_WARN("No active camera set - renderer skipping frame");
@@ -206,6 +181,7 @@ void cubos::engine::rendererPlugin(Cubos& cubos)
     cubos.addComponent<SpotLight>();
     cubos.addComponent<DirectionalLight>();
     cubos.addComponent<PointLight>();
+    cubos.addComponent<Viewport>();
 
     cubos.startupTag("cubos.renderer.init").after("cubos.window.init");
     cubos.tag("cubos.renderer.frame").after("cubos.transform.update");

engine/src/cubos/engine/renderer/viewport.cpp

@@ -0,0 +1,12 @@
+#include <cubos/core/ecs/component/reflection.hpp>
+#include <cubos/core/reflection/external/glm.hpp>
+
+#include <cubos/engine/renderer/viewport.hpp>
+
+CUBOS_REFLECT_IMPL(cubos::engine::Viewport)
+{
+    return core::ecs::ComponentTypeBuilder<Viewport>("cubos::engine::Viewport")
+        .withField("position", &Viewport::position)
+        .withField("size", &Viewport::size)
+        .build();
+}