From e422ff5c3892c55d6aacf5d860c2e59546851d16 Mon Sep 17 00:00:00 2001
From: MichalSt <michalstachowicz.95@gmail.com>
Date: Wed, 11 Oct 2023 22:57:53 +0100
Subject: [PATCH] Added the ParticleEmitter component. #60 Added one to the
 default scene.

---
 CMakeLists.txt                       |  2 ++
 source/Component/ParticleEmitter.cpp | 19 +++++++++++++++
 source/Component/ParticleEmitter.hpp | 35 ++++++++++++++++++++++++++++
 source/System/SceneSystem.cpp        |  7 ++++++
 4 files changed, 63 insertions(+)
 create mode 100644 source/Component/ParticleEmitter.cpp
 create mode 100644 source/Component/ParticleEmitter.hpp

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1508450..bceb418 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -53,6 +53,8 @@ source/Component/Input.hpp
 source/Component/Label.hpp
 source/Component/Mesh.cpp
 source/Component/Mesh.hpp
+source/Component/ParticleEmitter.hpp
+source/Component/ParticleEmitter.cpp
 source/Component/RigidBody.cpp
 source/Component/RigidBody.hpp
 source/Component/Lights.cpp
diff --git a/source/Component/ParticleEmitter.cpp b/source/Component/ParticleEmitter.cpp
new file mode 100644
index 0000000..796a777
--- /dev/null
+++ b/source/Component/ParticleEmitter.cpp
@@ -0,0 +1,19 @@
+#include "ParticleEmitter.hpp"
+
+namespace Component
+{
+    ParticleEmitter::ParticleEmitter(const TextureRef& p_texture)
+        : diffuse{p_texture}
+        , emit_position{glm::vec3(0.f)}
+        , emit_velocity_min{glm::vec3(-0.5f, 1.f, -0.5f)}
+        , emit_velocity_max{glm::vec3( 0.5f, 1.f,  0.5f)}
+        , spawn_period{1.f}
+        , time_to_next_spawn{0.f} // Spawn on creation.
+        , spawn_count{3u}
+        , lifetime{7.f}
+        , max_particle_count{1000}
+        , particles{}
+    {
+        particles.reserve(max_particle_count);
+    }
+}
\ No newline at end of file
diff --git a/source/Component/ParticleEmitter.hpp b/source/Component/ParticleEmitter.hpp
new file mode 100644
index 0000000..89b0d47
--- /dev/null
+++ b/source/Component/ParticleEmitter.hpp
@@ -0,0 +1,35 @@
+#pragma once
+
+#include "Component/Texture.hpp"
+#include "glm/vec3.hpp"
+#include "glm/vec4.hpp"
+
+#include "Utility/Config.hpp"
+
+namespace Component
+{
+    struct Particle
+    {
+        glm::vec4 position;
+        glm::vec4 velocity;
+        DeltaTime lifetime;
+    };
+
+    class ParticleEmitter
+    {
+    public:
+        ParticleEmitter(const TextureRef& p_texture);
+
+        TextureRef diffuse;           // Texture applied to all the particles.
+        glm::vec3 emit_position;      // Position particles emit from.
+        glm::vec3 emit_velocity_min;  // Minimum starting velocity in m/s.
+        glm::vec3 emit_velocity_max;  // Maximum starting velocity in m/s.
+        DeltaTime spawn_period;       // Duration between particle spawn attempts.
+        DeltaTime time_to_next_spawn; // Duration remaining to next spawn attempt.
+        size_t spawn_count;           // How many particles to spawn every spawn_period.
+        DeltaTime lifetime;           // Duration in seconds a particle stays alive before being removed.
+        size_t max_particle_count;    // Max number of particles that can be alive concurrently.
+
+        std::vector<Particle> particles;
+    };
+}
\ No newline at end of file
diff --git a/source/System/SceneSystem.cpp b/source/System/SceneSystem.cpp
index 1576897..a10191d 100644
--- a/source/System/SceneSystem.cpp
+++ b/source/System/SceneSystem.cpp
@@ -14,6 +14,7 @@
 #include "RigidBody.hpp"
 #include "Texture.hpp"
 #include "Transform.hpp"
+#include "Component/ParticleEmitter.hpp"
 
 // Geometry
 #include "Geometry.hpp"
@@ -200,6 +201,12 @@ namespace System
                 m_scene.m_entities.addEntity(Component::Label{"Spotlight 1"}, spotlight);
             }
         }
+
+        { // Particle
+            m_scene.m_entities.addEntity(
+                Component::Label{"Particle emitter"},
+                Component::ParticleEmitter{mTextureSystem.getTexture(Config::Texture_Directory / "marcy.jpeg")});
+        }
     }
 
     void SceneSystem::constructBoxScene()