From b7f4f0e4bf12321c030b4b6e5f82aa748e04e88b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lu=C3=ADs=20Fonseca?= <luis@lhf.pt>
Date: Sun, 18 Jun 2023 11:17:48 +0100
Subject: [PATCH] feat(engine): add collisions sample

---
 engine/samples/CMakeLists.txt      |   1 +
 engine/samples/collisions/main.cpp | 163 +++++++++++++++++++++++++++++
 2 files changed, 164 insertions(+)
 create mode 100644 engine/samples/collisions/main.cpp

diff --git a/engine/samples/CMakeLists.txt b/engine/samples/CMakeLists.txt
index 9845cb5b7..657149659 100644
--- a/engine/samples/CMakeLists.txt
+++ b/engine/samples/CMakeLists.txt
@@ -43,5 +43,6 @@ make_sample(DIR "input" ASSETS)
 make_sample(DIR "assets/json" ASSETS)
 make_sample(DIR "assets/bridge" ASSETS)
 make_sample(DIR "renderer")
+make_sample(DIR "collisions" COMPONENTS)
 make_sample(DIR "scene" COMPONENTS ASSETS)
 make_sample(DIR "cars" COMPONENTS ASSETS)
diff --git a/engine/samples/collisions/main.cpp b/engine/samples/collisions/main.cpp
new file mode 100644
index 000000000..a36598db8
--- /dev/null
+++ b/engine/samples/collisions/main.cpp
@@ -0,0 +1,163 @@
+#include <glm/gtc/random.hpp>
+
+#include <cubos/core/geom/box.hpp>
+#include <cubos/core/gl/debug.hpp>
+#include <cubos/core/log.hpp>
+#include <cubos/core/settings.hpp>
+
+#include <cubos/engine/collisions/aabb.hpp>
+#include <cubos/engine/collisions/broad_phase_collisions.hpp>
+#include <cubos/engine/collisions/colliders/box.hpp>
+#include <cubos/engine/collisions/plugin.hpp>
+#include <cubos/engine/input/plugin.hpp>
+#include <cubos/engine/renderer/plugin.hpp>
+#include <cubos/engine/transform/plugin.hpp>
+
+using cubos::core::Settings;
+using cubos::core::ecs::Commands;
+using cubos::core::ecs::Entity;
+using cubos::core::ecs::Query;
+using cubos::core::ecs::Read;
+using cubos::core::ecs::Write;
+using cubos::core::geom::Box;
+using cubos::core::io::Key;
+using cubos::core::io::Modifiers;
+
+using cubos::engine::BoxCollider;
+using cubos::engine::BroadPhaseCollisions;
+using cubos::engine::ColliderAABB;
+using cubos::engine::InputAction;
+using cubos::engine::InputBindings;
+
+using namespace cubos::engine;
+
+struct State
+{
+    bool collided = false;
+
+    Entity a;
+    Entity b;
+
+    glm::vec3 aRotationAxis;
+    glm::vec3 bRotationAxis;
+};
+
+static void settings(Write<Settings> settings)
+{
+    settings->setBool("assets.io.enabled", false);
+}
+
+static void init(Commands commands, Write<Input> input, Write<ActiveCameras> camera)
+{
+    // Add procedural asset for detecting a reset action on a space key press.
+    auto bindings = InputBindings{};
+    bindings.actions()["reset"].keys().push_back({Key::Space, Modifiers::None});
+    input->bind(bindings);
+
+    // Spawn the camera.
+    camera->entities[0] =
+        commands.create()
+            .add(Camera{.fovY = 60.0, .zNear = 0.1F, .zFar = 100.0F})
+            .add(LocalToWorld{})
+            .add(Position{{-4.0, 1.5, 0}})
+            .add(Rotation{glm::quatLookAt(glm::normalize(glm::vec3{3.0, -1.0, 0.0}), glm::vec3{0.0, 1.0, 0.0})})
+            .entity();
+}
+
+static void addColliders(Write<State> state, Write<BroadPhaseCollisions> collisions, Commands commands)
+{
+    state->a = commands.create()
+                   .add(BoxCollider{})
+                   .add(LocalToWorld{})
+                   .add(Position{glm::vec3{0.0F, 0.0F, -2.0F}})
+                   .add(Rotation{})
+                   .entity();
+    state->aRotationAxis = glm::sphericalRand(1.0F);
+    collisions->addEntity(state->a);
+
+    state->b = commands.create()
+                   .add(BoxCollider{})
+                   .add(LocalToWorld{})
+                   .add(Position{glm::vec3{0.0F, 0.0F, 2.0F}})
+                   .add(Rotation{})
+                   .entity();
+    state->bRotationAxis = glm::sphericalRand(1.0F);
+    collisions->addEntity(state->b);
+}
+
+static void updateTransform(Write<State> state, Read<Input> input, Query<Write<Position>, Write<Rotation>> query)
+{
+    auto [aPos, aRot] = query[state->a].value();
+    auto [bPos, bRot] = query[state->b].value();
+
+    if (state->collided)
+    {
+        if (input->pressed("reset"))
+        {
+            state->collided = false;
+
+            aPos->vec = glm::vec3{0.0F, 0.0F, -2.0F};
+            aRot->quat = glm::quat{1.0F, 0.0F, 0.0F, 0.0F};
+            state->aRotationAxis = glm::sphericalRand(1.0F);
+
+            bPos->vec = glm::vec3{0.0F, 0.0F, 2.0F};
+            bRot->quat = glm::quat{1.0F, 0.0F, 0.0F, 0.0F};
+            state->bRotationAxis = glm::sphericalRand(1.0F);
+        }
+        return;
+    }
+
+    aRot->quat = glm::rotate(aRot->quat, 0.01F, state->aRotationAxis);
+    aPos->vec += glm::vec3{0.0F, 0.0F, 0.01F};
+
+    bRot->quat = glm::rotate(bRot->quat, 0.01F, state->bRotationAxis);
+    bPos->vec += glm::vec3{0.0F, 0.0F, -0.01F};
+}
+
+static void updateCollided(Query<Read<BoxCollider>> query, Write<State> state, Read<BroadPhaseCollisions> collisions)
+{
+    for (auto [entity, collider] : query)
+    {
+        for (auto& [collider1, collider2] : collisions->candidates(BroadPhaseCollisions::CollisionType::BoxBox))
+        {
+            if (collider1 == entity || collider2 == entity)
+            {
+                state->collided = true;
+                break;
+            }
+        }
+    }
+}
+
+static void render(Query<Read<LocalToWorld>, Read<BoxCollider>, Read<ColliderAABB>> query)
+{
+    for (auto [entity, localToWorld, collider, aabb] : query)
+    {
+        cubos::core::gl::Debug::drawWireBox(collider->shape, localToWorld->mat * collider->transform);
+        cubos::core::gl::Debug::drawWireBox(aabb->box(), glm::translate(glm::mat4{1.0}, aabb->center()),
+                                            glm::vec3{1.0, 0.0, 0.0});
+    }
+}
+
+int main()
+{
+    auto cubos = Cubos();
+
+    cubos.addPlugin(collisionsPlugin);
+    cubos.addPlugin(rendererPlugin);
+    cubos.addPlugin(inputPlugin);
+
+    cubos.addResource<State>();
+
+    cubos.startupSystem(settings).tagged("cubos.settings");
+    cubos.startupSystem(init);
+
+    cubos.startupSystem(addColliders);
+
+    cubos.system(updateTransform).beforeTag("cubos.transform.update");
+    cubos.system(updateCollided).tagged("updated").afterTag("cubos.collisions");
+    cubos.system(render).afterTag("updated");
+
+    cubos.run();
+    return 0;
+}
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